Variable Cycle Gas Turbines Enabled by Active Fluidic Control of the Nozzle Guide Vane Throat
TOPIC: Variable Cycle Gas Turbines Enabled by Active Fluidic Control of the Nozzle Guide Vane Throat
ABSTRACT:
Experiments were conducted to validate the building blocks of a fluidically controlled variable area turbine concept that uses injected high-pressure air to effectively reduce the choke area of the turbine engine. Preliminary results from a simple quasi-1D converging-diverging nozzle, with an injection flow slot upstream of the throat, showed a 2.2:1 ratio between throttled mass flow rate and injected mass flow rate at a constant nozzle pressure ratio. The penetration of the injection flow and corresponding reduction in the primary flow streamtube were successfully visualized using a shadowgraph technique. Building on this success, a representative single passage nozzle guide vane transonic flowpath was constructed to demonstrate feasibility beyond the quasi-1D converging-diverging nozzle. Both secondary slot blowing from the vane pressure surface and vane suction surface just upstream of the passage throat again successfully reduced primary flow. In addition, fluidic vortex generators were used on the adjacent suction surface to reduce total pressure loss and further throttle the primary flow. A simplified model was developed to assess the driving design factors that influence the blocked flow fraction and throttling effectiveness of the actuators. The model approximates slot injection using a simplified stream tube analysis, neglecting mixing with the primary passage flow. Throttling performance is predicted for fluidic actuators with different widths, orientations, streamwise locations, and pressure ratios. Two-dimensional CFD of injection in the nozzle guide vane passage reported strong agreement with the results of the simple model using the variable width duct. This model has potential application for optimizing fluidic VAT throttling designs while saving on the cost of high-fidelity testing and production of these configurations.
BIO:
Dr. Jeffrey Bons received his BS, MS, and PhD at MIT in Course 16 (’88, ’90, ’97). In addition to his 12 years of active duty service as an officer in the U.S. Air Force, Dr. Bons has been a faculty member for 27 years: 5 years at the Air Force Institute of Technology (AFIT) in Dayton, OH, 5 years at Brigham Young University in Provo, UT, and 17 years at The Ohio State University in Columbus, OH. His research specialties include gas turbine propulsion (particularly hot section performance in particle-laden environments) and aero applications of active flow control. He is a fellow of ASME and an associate fellow of AIAA. Dr. Bons and his wife are the parents of 6 children, grandparents of 10 and live in Dublin, Ohio.
Building-block Flow Model for Computational Fluids
TOPIC: Building-block Flow Model for Computational Fluids
Abstract: The predictive capabilities of computational fluid dynamics (CFD), critical for aerodynamic design, hinge on the development of accurate closure models. However, no practical model has emerged as universally applicable across the broad range of flow regimes of interest to the industry. We introduce a closure model for CFD, referred to as the Building-block Flow Model (BFM). The foundation of the model rests on the premise that a finite collection of simple flows encapsulates the essential physics necessary to predict more complex scenarios. The BFM is implemented using artificial neural networks and introduces five unique advancements within the framework of large-eddy simulation: (1) It is designed to predict multiple flow regimes (laminar flow, wall turbulence under zero, favorable, and adverse mean-pressure gradients, separation, statistically unsteady turbulence, and wall roughness effects); (2) It leverages information-theoretic dimensional analysis to select the most relevant non-dimensional input/output variables; (3) It ensures consistency with numerical schemes and gridding strategy by accounting for numerical errors; (4) It is directly applicable to arbitrary complex geometries; (5) It can be scaled up to model additional flow physics in the future if needed (e.g., shockwaves and laminar-to-turbulent transition). The BFM is utilized to predict key quantities of interest in a wide range of cases, such as turbine blades with roughness, speed bumps, and aircraft in landing configuration. In all cases, the BFM demonstrates similar or superior capabilities in terms of accuracy and computational efficiency compared to previous state-of-the-art closure models. We also discuss ongoing efforts to extend the model to supersonic and hypersonic flows with applications to Entry, Descent and Landing (EDL) vehicles.
Mechanisms, Benefits, and Challenges of Boundary Layer Ingestion Propulsion
TOPIC: Mechanisms, Benefits, and Challenges of Boundary Layer Ingestion Propulsion
Abstract: Boundary layer ingestion (BLI) is a propulsion concept where thrust is generated by accelerating flow in a vehicle’s boundary layer or wake. The lower momentum of this flow, relative to the free stream, means the thrust can be generated using less power than conventional propulsion, and BLI has been proposed for numerous high-efficiency aircraft concepts. This seminar will review the fundamental mechanisms of BLI power savings and challenges associated with performance of the propulsor turbomachinery. Wind tunnel experiments led by the GTL on the D8 “double bubble” aircraft concept demonstrated power savings with BLI on the order of 10% and characterized non-uniform engine inlet flows inherent to BLI. These inlet distortions have adverse effects on efficiency, aeromechanics, stability, and acoustics of BLI fans, and new analysis methods and design approaches are required for turbomachinery operating in non-axisymmetric flow to enable the potential benefits of BLI.
Bio: David K. Hall is an Assistant Professor of Aerospace Engineering at The Pennsylvania State University, where he leads the Aircraft Propulsion Research Group, focused on developing advanced aircraft propulsion concepts for improved capability and environmental sustainability. Prior to joining the Penn State faculty in 2021, he led the Propulsion Group at Aurora Flight Sciences and worked as a Postdoctoral Associate and Research Engineer at the GTL. He earned his Bachelor of Science in Mechanical Engineering and Materials Science, and Mathematics, from Duke University, and his S.M. and Ph.D. in Aeronautics and Astronautics from MIT, where he worked as a graduate student in the GTL on the NASA N+3 project, supporting the development of the boundary layer ingesting propulsion system of the ultra-efficient D8 “double bubble” transport aircraft concept.
Aeroelasticity of Coriolis Meters Operating on Bubbly Liquids
TOPIC: Aeroelasticity of Coriolis Meters Operating on Bubbly Liquids
ABSTRACT:
Coriolis flow meters set the standard for high accuracy, low maintenance and calibration requirements, and multi-variable measurement capabilities. For these and other reasons, Coriolis meters have become the largest and fastest growing class of flow meters in the global market. Coriolis meters typically excel at single-phase applications; however, the accuracy of Coriolis meters is well-known to degrade on bubbly liquids. This reduced accuracy on bubbly liquids serves to limit both the adoption rate and the utility of Coriolis meters in many applications where bubbly flow conditions are either consistently, or intermittently, present.
This presentation describes the mechanisms through which bubbly flows degrade the accuracy of Coriolis meter and presents reduced order models that capture these effects. The presentation also describes an approach to augment Coriolis meters with a process fluid sound speed measurement to mitigate errors associated with Coriolis meters operating on bubbly flows.
Utilizing SONAR-based beam-forming techniques, acoustic pressure transducers installed on either side of a Coriolis meter are used to quantify the sound speed and gas void fraction within the Coriolis meter and mitigate errors in the mass flow, density, and volumetric flow reported by Coriolis meters operating on bubbly mixtures of air and water. By improving accuracy of Coriolis meters operating on bubbly liquids, speed of sound augmented Coriolis meters offer the potential to improve the utility of Coriolis meters on many existing applications and expand the application space of Coriolis meters to address additional multiphase measurement challenges.
BIO:
Daniel Gysling graduated from the Gas Turbine Lab in 1993, receiving his doctorate under Professors Greitzer, Kerrebrock, Dugundji, and Ingard. Dr Gysling worked within the “Smart Engines” program studying dynamic control of rotating stall and surge in compression systems. Leveraging his multidisciplinary education gained working as part of the Smart Engines team, Dr. Gysling has addressed a wide range of aerodynamic, aerothermal, and aeroelastic operability issues of gas and wind turbines and was the primary inventor of SONAR-based multiphase flow measurement technology and the Aeromechanical Identification Methodology (AIM) for flutter in turbomachines. Dr. Gysling is currently the founder and CEO of CorVera, LLC. – a company developing technology to improve the accuracy of Coriolis meters operating on multiphase flows.
Additive Manufacturing and its Role in the Post-Covid Aviation Industry
TOPIC: Additive Manufacturing and its Role in the Post-Covid Aviation Industry
ABSTRACT:
Air travel demand is returning quickly post-Covid, but a confluence of issues is making it difficult for the production supply chain to keep up. First, anti-competitive industry consolidation over the past several decades has decimated production capacity and resulted in shortages of key components (e.g., castings). Second, layoffs and buyouts during COVID caused a massive brain drain in heavy industry which is surprisingly reliant on skilled technicians. Third, engine reliability issues (e.g., GTF, LEAP) have grounded new aircraft, causing older aircraft to remain in-service longer. These factors are now forcing industry to consider alternative means of making parts, and additive manufacturing has emerged as a potential route for alleviating supply chain issues, lowering part costs, and getting planes flying again. This talk will summarize some of the challenges currently limiting additively manufactured hardware in safety-critical applications and my lab’s efforts to overcome these issues using fundamental materials science principles. In particular, I will describe specialized post-processing heat treatments, developed in my lab, which improve the creep-resistance of 3D-printed Ni-base superalloys, thus enabling their use in the hot section of mature aeroengines.
The Impact of Combustor Turbulence on Turbine Loss Mechanisms
TOPIC: The Impact of Combustor Turbulence on Turbine Loss Mechanisms
ABSTRACT:
This seminar will discuss an important aspect of combustor-turbine interaction in a typical gas turbine. It will show that the extremely high levels of turbulence created in the combustion chamber of a jet engine increase the loss in a turbine blade row located downstream of it by 47%. This contrasts to industry design methods which predict no increase in loss. The talk will explain the physical mechanism responsible for this change, allowing it to be modelled, and exploited, in the design of jet engines. Future designs of an integrated combustor-turbine system can result in a reduction of up to 1% specific fuel consumption, which is important for saving resources and reducing emissions in aviation.
Aero-Thermal-Mechanical Interactions in Ultra High-Speed Micro Gas Turbines
TOPIC: Aero-Thermal-Mechanical Interactions in Ultra High-Speed Micro Gas Turbines
ABSTRACT:
Aero-thermal induced mechanical response of engine components in an ultra high-speed micro gas turbine engine system is assessed. Scaling down gas turbine engines for high performance requirements dictates substantial thermal-induced effects on engine operation due to high temperature gradient relative to that in conventional large gas turbine engines. Experiments indicate that sustainable operation is limited by the mechanical response of the shaft-bearing housing system. It is hypothesized that this is due to thermal-induced mechanical deformation of the shaft-bearing housing that results in bearing clearance variation that differs from the design intent. An unsteady CFD conjugate heat transfer computation of flow and temperature distribution in the engine system is first implemented; this is followed by determining the corresponding mechanical deformation of engine components based on finite element analysis. The computed result shows that at the beginning of the engine start-up process, the radial expansion of the shaft is larger than that of the bearing housing, resulting in a smaller bearing clearance. Toward steady-state operation, a larger bearing clearance is observed. The computed results and experimental observation are in agreement thus confirming the hypothesis. The key controlling non-dimensional parameters characterizing the aerothermal-mechanical interaction and response are identified using a reduced order model that yields thermal-induced mechanical deformation in agreement with the unsteady computations. For a geometrically similar engine system, the controlling thermal and structural parameters consist of: (1) shaft fin parameter, (2) housing fin parameter, (3) ratio of heat diffusivity of housing to that of the shaft, (4) 3 cooling flow parameters, and (5) ratio of the coefficient of thermal expansion of the housing to that of the shaft. The non-dimensional parameters serve as a guideline for developing strategies for controlling bearing clearance under the acceptable margin, including selecting shaft and housing materials with appropriate properties as well as tailoring the cooling flow. An approximate scaling rule for thermal-induced shaft-bearing housing clearance variation in engines of various sizing is formulated.
A Megawatt-Class Electrical Machine Technology Demonstrator for Turbo-Electric Propulsion
TOPIC: A Megawatt-Class Electrical Machine Technology Demonstrator for Turbo-Electric Propulsion
ABSTRACT:
While continued propulsion system and turbomachinery improvements are necessary, they are not sufficient to address the 2050 aviation sustainability goals. Without intervention aviation will emit a cumulative total of over 20 billion tons of CO2 by then. An ambitious target is to achieve a net-zero economy by 2050. The step change achievements needed to address the climate grand challenge are unconventional aircraft configurations with integrated and distributed propulsion systems. Independent of the energy carrier (battery, SAF, H2, NH3), MW class electrical machines will play a key role in greening aviation. To address the climate and sustainability grand challenge, a high specific power fully air-cooled 1MW electrical machine is being developed, conceived to advance electrified aviation but also suitable for other ground-based applications. One application is integration in an aero-engine as a motor-drive for turbo-electric propulsion. The emphasis of this project is on risk mitigation experiments and technology demonstration of a 1 MW integrated motor drive with performance estimates exceeding the NASA 2030 goals.
Establishing a 1kW Gas Turbine Research Facility
TOPIC: Establishing a 1kW Gas Turbine Research Facility
ABSTRACT:
A new kW-scale gas turbine research facility has been established in the MIT Gas Turbine Laboratory. This facility will be used to assess and quantify the unique dynamic properties in kW-scaled engines. The seminar will cover the process of establishing the facility, focusing on the lessons learned. It will also cover the research goals which this facility was built to address, along with a discussion of how the experience of setting up and operating the engine has influenced those goals. Establishing the facility involved communication with numerous groups of individuals, including vendors, contractors, and MIT management. Every step involved overcoming unforeseen challenges, including meeting mandated environmental requirements. This seminar will serve as a way to share that experience with any individuals who may be setting up their own experimental research facility, so that they may avoid the same challenges.
Environmental barrier coating to mitigate metal ignition in high pressure oxygen environments
TOPIC: Environmental barrier coating to mitigate metal ignition in high pressure oxygen environments
ABSTRACT:
Oxygen-rich turbopumps are essential for emerging oxidizer-rich and full-flow staged combustion rocket engines. The turbine in an oxygen-rich turbopump subjects materials to high-pressure, high-temperature gaseous oxygen environments, amplifying the risk of metal fires which serve as catastrophic, single-point failure modes. One candidate approach for mitigating the risk of metal ignition, specifically through particle impact ignition, is to coat metallic components with inert ceramic environmental barrier coatings (EBCs); however, such coatings are susceptible to delamination under the rapid thermal transients upon engine startup and shutdown. Here, we investigate the delamination risk of a novel ductile phase-toughened composite EBC under a nominal flight cycle for a reusable boost-stage engine. The results show that cold shock at shutdown gives rise to the highest energy release rate for coating delamination, of order 100 J/m2, which will cause conventional monolithic ceramic coatings to delaminate. By contrast, we predict that the composite EBC of present interest resists transient-driven delamination due to crack bridging while protecting the underlying metal from particle impact ignition. Finally, the talk will highlight strategies to mitigate damage by tailoring the operating environment and coating design.
Tail-Integrated Boundary Layer Ingesting Propulsion Systems for Turbo-Electric Aircraft
JOINT ASML/GAS TURBINE LABORATORY SEMINAR
DATE: Thursday, 4.6.23
TIME: 4:00pm
LOCATION: 31-270
SPEAKER: Zhibo Chen, GTL Student
TOPIC: Tail-Integrated Boundary Layer Ingesting Propulsion Systems for Turbo-Electric Aircraft
ABSTRACT:
This seminar will present conceptual design guidelines and results for a tail-integrated propulsion system for a turbo-electric civil transport aircraft with boundary layer ingestion (BLI). The aerodynamic performance goal is separation-free and shock-free operation at cruise with fuel burn reduction, compared with a baseline conventional aircraft for the same mission. The assessment of BLI benefits is based on calculations using CFD and TASOPT software, both to characterize the design challenges and to establish the physical mechanisms for resolving these challenges. The guidelines include a “horseshoe” inlet to accept the non-uniform flow without incurring separation, a nacelle profile similar to supercritical airfoils to reduce shock strength, and an annular nozzle to eliminate flow separation between tail-BLI propulsors. The conceptual design has nine BLI propulsors with electric fans on an axisymmetric tail of a single-aisle aircraft. The fans are powered by twin underwing turbofans. The estimated benefit of the tail-BLI, twin underwing turbofan aircraft is 10.4% in Payload-Range Fuel Consumption (PRFC) at a cruise Mach number of 0.8, compared to a baseline twin underwing turbofan configuration. Sensitivity studies further show that a 1% increase in installed (i.e. with BLI) fan isentropic efficiency translates to 0.8% rise in PRFC benefit.
BIO:
Zhibo Chen is a PhD candidate at the MIT Gas Turbine Laboratory (GTL), working with Prof. Spakovszky, Prof. Greitzer, Dr. Sabnis, and Dr. Galbraith. He received a S.M. degree from MIT AeroAstro in 2022, a B.S.E. in Aerospace Engineering from the University of Michigan – Ann Arbor and a B.S. in Mechanical Engineering from Shanghai Jiao Tong University in 2020. His research interests include turbo-electric propulsion, boundary layer ingestion, and turbomachinery. In his leisure time, he is a photographer with passion in landscape, portrait, and events.
Novel Lifing Techniques for Additive Manufacturing Applications
JOINT AMSL/GAS TURBINE LABORATORY SEMINAR
DATE: Tuesday, 4.4.23
TIME: 4:00pm
LOCATION: 31-270
SPEAKER: Dr. Luke C. Sheridan, USAF AFMC AFRL
TOPIC: Novel Lifting Techniques for Additive Manufacturing Applications
ABSTRACT:
Additive manufacturing (AM) introduces microstructural and material complexities that are not as prevalent in many traditionally manufactured materials and components. Complicated microstructure induced from high thermal gradients and large cooling rates introduce interesting crack growth behavior, and the building block style of overlapping single weld pools often create opportunities for lack of fusion defects, gas porosity, and keyhole porosity to manifest in AM materials. These complexities can often appear to complicate traditional methods of lifing, but through the use and further development of historical lifing tools used for traditionally manufactured materials and components, lifing can be performed with some ease and accuracy. This talk highlights some recent developments in lifing AM components, and walks through the enhancement of historical lifing tools to accommodate the idiosyncrasies of AM alloys in terms of fatigue crack initiation and propagation to failure. Additionally, initial applications to aerospace and turbine engine applications are described briefly, and new insights and inspection methodologies are described. This talk provides a good starting point for understanding the complexities of life prediction for AM materials, and introduces new routes for further research and application in the aerospace community.
BIO:
Dr. Luke Sheridan is a mechanical engineer with the Aerospace Systems Directorates Turbine Engine Division at Wright Patterson Air Force Base. He is currently involved in research related to the structural integrity and performance of turbine engine components manufactured under both traditional and advanced manufacturing methods. His responsibilities include material and component evaluation for research and fielded components using experimental and analytical methods to assess various structural dynamic behavior and resulting failure mechanisms. He is a recognized advanced manufacturing subject matter expert for numerous in-house and industry programs including two large joint demonstrations program with partners from across the Air Force and the DoD. Dr. Sheridan also currently serves as co-locate to the Air Force Life Cycle Management Center’s Propulsion Directorate and facilitates communication between the two organizations and guides technology and maintenance roadmap development in cooperation with the Propulsion Technology Office.
Dr. Sheridan joined the Air Force via the Pathways internship program in May 2016 as a first year Ph.D. student and was assigned to the Structural Integrity Branch of the Turbine Engine Division. Within one and half years, he transitioned to full civil service and strengthened his contribution to the Turbine Engine and surrounding communities as a recognized additive manufacturing expert especially in the fields of structural mechanics and lifing. Prior to his position with the Air Force Research Laboratory (AFRL), Dr. Sheridan attended Wright State University where he received a B.S. and M.S. of Mechanical Engineering. In March 2020, Dr. Sheridan also earned his Ph.D. in Engineering from Wright State University. Dr. Sheridan’s CV includes 18 Journal papers (~190 citations), 5 book chapters, and 25 conference presentations and invited talks.
Mesh Convergence of RANS Solutions Using Expert Crafted and Output-Based Adapted Meshes
GAS TURBINE LABORATORY SEMINAR
DATE: Thursday, 3.23.23
TIME: 4:00pm
LOCATION: 31-270
SPEAKER: Marshall Galbraith, Research Engineer in the GTL and ACDL
TOPIC: Mesh Convergence of RANS Solutions using Expert Crafted and Output-Based Adapted Meshes
ABSTRACT:
Mesh convergence of RANS solutions for a multi-element airfoil and the NASA Juncture Flow Model computed with a variety of flow solver software packages using output-based adapted meshes are compared with solution convergence computed using expert crafted meshes adhering to "best practices”. The adapted meshes are generated using an optimization process implemented with the MIT Solution Adaptive Numerical Simulator (SANS) software. The adaptation process seeks to find a mesh that minimizes the error estimate of a given output functional subject to a maximum number of degrees of freedom. The multi-element airfoil expert crafted meshes are the result of a systematic study of the influence of a range of meshing parameters on solution accuracy, and the expert crafted meshes are generated by based on decades of experience with generation “best practice” meshes. Using the adapted meshes generally leads to more than two orders of magnitude reduction in lift and drag error relative to the expert crafted meshes of a comparable node count for all of the CFD solvers. Alternatively, the node counts of the adapted meshes are more than an order of magnitude smaller than the manually generated meshes for a given lift and drag error level.
BIO:
Marshall Galbraith is a research engineer the GTL and ACDL.
737 Max Crashes: Ethical Questions and Responsibilities
GAS TURBINE LABORATORY SEMINAR
DATE: Thursday, 9 March 2023
TIME: 4:00pm
LOCATION: 31-270
SPEAKER: Javier de Luis, Ph.D., Professor Emeritus
TOPIC: 737 Max Crashes: Ethical Questions and Responsibilities
ABSTRACT:
The two fatal crashes of the 737-Max within months of each other resulted not only in the deaths of 346 people, but also in an unprecedented and ongoing indictment of the way American commercial aircraft are being designed, tested and certified. The crashes lead to the grounding of an entire class of aircraft for 20 months, something that had never happened before, with economic repercussions that spanned the entire country. While the technical causes of the crash were quickly identified, the investigation into how these flaws were allowed to be incorporated and deployed yielded troubling questions about the management and certification processes that have been put in place over the last twenty years.
Dr. Javier de Luis lost his sister on Ethiopian Flight 302. In the years since the crash, he has taken on a role of providing technical support to the victims families in their dealings with the FAA, EASA, and other agencies and organizations. This talk is a “case study” on the failures of the 737 Max, how we got to this point, and what can we, as individual engineers, educators, and technical managers, do to prevent it from happening again.
BIO:
Dr. Javier de Luis earned BS (1983), MS (1985), and PhD (1989) in Aeronautics and Astronautics from MIT, as well as an MS (2003) from the Sloan School of Management. His professional interests are in the fields of safety, aerospace research and operations, engineering design and analysis, and technology management. Dr. de Luis joined Payload Systems Inc. in 1989 as a staff scientist, and later as the Chief Scientist and CEO at the company, prior to its merger with Aurora Flight Sciences. While at Aurora, he was Chief Scientist and Vice President for Research and Development until 2016. Presently, he holds a Lecturer appointment at MIT.
Dr. de Luis has served as the principal investigator/project manager for multiple aerospace research projects, including the Middeck 0-gravity Dynamics Experiment (MODE) and Middeck Active Control Experiment (MACE). He has published papers on such diverse topics as piezoelectric actuators and intelligent structures, structural control, distributed sensing and computing, and design and development of spaceflight systems. He authored the seminal paper in the field of Smart Materials, “Use of Piezoelectric Actuators as Elements of Intelligent Structures”, which has been referenced over 3541 times (as of April-2022) by subsequent journal and conference publications.
A Half-Century of Research in Fluid Dynamics: Hemodynamics to Hypersonics
GAS TURBINE LABORATORY SEMINAR
DATE: Thursday, 23 February 2023
TIME: 4:00pm
LOCATION: 31-270
SPEAKER: Wesley Harris, Charles Stark Draper Professor of Aeronautics and Astronautics
TOPIC: A Half-Century of Research in Fluid Dynamics: Hemodynamics to Hypersonics
ABSTRACT:
This lecture will speak on the primary engineering challenges, related research hypotheses, relevant questions, appropriate research tools, and assessment of results in selected areas of hypersonics, helicopter rotor acoustics, unsteady nonlinear transonics, and hematology. This corpus of work is driven by seminal achievements of outstanding graduate students, often working in mutual critical groups. This diversity of research investigations is matched by the diversity of participating graduate students, including racially underrepresented, women, and international students. The supporting (sustainable) research ecosystem also contributed to the quality of the process and results.
BIO:
Currently, Dr. Wesley L. Harris is a Charles Stark Draper Professor of Aeronautics and Astronautics, MIT. He served as Head of the Department of Aeronautics and Astronautics, MIT, 2003-2008, an Associate Administrator for Aeronautics, NASA, 1993-1995, performed as Vice President and Chief Administrative Officer, University of Tennessee Space Institute, Tullahoma, Tennessee (1990-1993), and served as Dean of the School of Engineering and Professor of Mechanical Engineering at the University of Connecticut (1985-1990). His academic research is associated with unsteady aerodynamics, aeroacoustics, rarefied gas dynamics, sustainment of capital assets, hypersonics and chaos in sickle cell disease. He has served on committees of the AIAA, AHS, NTA, and was elected Vice President of NAE in 2022. Received PhD, Princeton University, 1968.
Power Harvesting from Shock Waves: The Axial Bladeless Turbine
GAS TURBINE LABORATORY SEMINAR
DATE: Thursday, 16 February 2023
TIME: 4:00pm
LOCATION: 31-270
SPEAKER: James Braun, Research Assistant Professor, Purdue
TOPIC: Power Harvesting from Shock Waves: The Axial Bladeless Turbine
ABSTRACT:
In the past decade, pressure gain combustion research has promised over ten percentage points of increase in power plant thermal efficiency. The impact of a mere two percent increase in fuel efficiency for airplane engines would save over one billion dollars for the United States per year, not to mention potential reductions in size, weight, complexity, and cost of engines. However, to realize such potential gains, the turbine must be effectively coupled with the Rotating Detonation Combustor (RDC), whose exhaust conditions differ substantially from the inlet conditions of the current state-of-the-art turbines.
In this talk, a new type of turbine will be introduced, the wavy-shaped bladeless turbine. This is an energy conversion unit for the combined power extraction and thrust increase which can be employed in high subsonic to hypersonic flows, and especially suitable for rotating detonation combustors. The seminar will include the current state of bladeless turbines, their advantages and performance characteristics. We will also briefly review the characteristics of rotating detonation combustors. Finally, the concept is validated in a supersonic wind tunnel through high-frequency probe-based and optical measurements.
BIO:
James Braun graduated from the KU Leuven (Belgium) as a mechanical engineer. He performed a research master at the von Karman Institute for fluid dynamics (Belgium) in 2015 within the Aerospace and Aeronautics department. His thesis was on the ‘Characterization of complex multi-physics flow in rotating detonation engines” for which he won the Prince Alexandre de Belgique price for the best presentation. He obtained his PhD from Purdue University (USA) in 2019 entitled “power harvesting from shock waves: the axial bladeless turbine”. In 2018, he was awarded the AIAA Gordon C Oates Air Breathing propulsion graduate award. He was an ORISE postdoctoral researcher in 2019 and is currently a research assistant professor at Purdue University.
An Alternate Means to Form Non-Dimensional Products in Dimensional Analysis
DATE: Thursday, 8 December 2022
TIME: 4:00 pm
LOCATION: 33-116
SPEAKER: John Clark, Principal Engineer, Air Force Research Laboratory
TOPIC: An Alternate Means to Form Non-Dimensional Products in Dimensional Analysis
ABSTRACT:
Dimensional analysis is taught early in an engineering curriculum, usually during the very first course in fluid mechanics. Such analysis has its root in the work of Lord Rayleigh, and the mechanics of the process as typically taught to students follows directly from the classic paper due to Buckingham on what has become known as the Pi Theorem. Students are meant to learn that dimensional analysis is a powerful tool for: developing insight with respect to flow physics, creating new models of physical processes, guiding the performance of experiments and flowfield simulations, aiding the sensible presentation of technical results, and fostering the replication of experiments and simulations. A critical step in process involves the selection of scaling parameters that are used in the formation of each non-dimensional product. Unfortunately, this selection can seem mysterious and arbitrary to the student encountering dimensional analysis for the first time. This can leave the student thinking that dimensional analysis is all well and good so long as one already knows the answer to a problem (e.g. that the drag on a cylinder in crossflow depends on the Reynolds number). However, an alternate technique for forming Pi products called the "step-by-step method" exists, and that is due to the late Prof. B. S. Massey of University College London. Discussion of the technique is largely absent from standard textbooks on fluid mechanics. So, this paper is intended to present his method to a wider audience and thus to encourage the adoption of the technique for use in engineering curricula. It requires no prior selection of scaling parameters, and it is amenable to easy implementation in a computer scripting language. It is also far less tedious and less prone to simple errors than the usual method. Accordingly, it encourages the student to explore the derivation of various non-dimensional formulations and thereby fosters learning. The method is briefly described, and examples of its application are presented for: the process of vortex shedding from a circular cylinder, the variation of the heat-transfer distribution along a flat plate, the scaling of turbines for laboratory testing, and the development of a model for the onset of transition to turbulence in turbomachinery flows. Needless to say, the form of the latter was not known at the outset, and dimensional analysis was essential to the formulation of the model and its successful application. A user-friendly implementation of the technique in Matlab is available for distribution to interested parties.
BIO:
John Clark is the Principal Engineer and Lead for Turbine Research in the Turbine Engine Division of the Aerospace Systems Directorate at the Air Force Research Laboratory. He earned his doctorate in Engineering Science from the University of Oxford where he was a student of the late Prof. Terry Jones at the Osney Laboratory. He has industrial experience from the Turbine Aerodynamics group at Pratt & Whitney. He began his career at AFRL in 2002, and he was the AIAA Engineer of the Year for 2012.
Enabling Sustainable Civil Aviation with High-efficiency Propulsion Systems
GAS TURBINE LABORATORY SEMINAR
DATE: Thursday, 17 November 2022
TIME: 4:00pm
LOCATION: 33-116
SPEAKER: Durgesh Chandel, RET Engineer, Intel
TOPIC: Enabling Sustainable Civil Aviation with High-efficiency Propulsion Systems
ABSTRACT:
Aerospace vehicles generate up to 2.5% of net global emissions, with short- to mid-range aircraft contributing about 65% of it (ICCT 2020). Decarbonizing this sector is key to reduce overall emissions and meet NASA’s net-zero emission goals by 2050. Under the CHEETA (Center for High-Efficiency Electrical Technologies for Aircraft) program, supported by NASA, we are developing design and technology for a next-generation transport aircraft powered by cryogenic hydrogen fuel-cells, in order to eventually, replace the conventional gas-turbine powered narrow-body fleet. Starting from a clean sheet design, CHEETA efforts are focused on enabling hydrogen-powered technology and systems for civil aircraft, minimizing net electric power requirements, and maximizing safety and performance at system- and component-level. In this talk, I will discuss the conceptual design of high-efficiency propulsion systems for enabling sustainable civil aviation. I utilize the boundary layer ingestion (BLI) on a distributed electric propulsors (DEP) architecture to maximize the propulsion system performance. A system-level approach is used to co-design these strongly coupled electric and aeropropulsive sub-systems. An extensive trade space exploration optimizes for a highly distributed 32-propulsors design, with 16% power savings relative to a no-BLI twin-engine electric aircraft (i.e., baseline). Further considerations of technological readiness level (TRL) and ease of manufacturing and operation for various components suggest a 9-propulsors (fuselage and over-the-wing mounted propulsors) configuration being optimal for the CHEETA mission. This design also shows about 14% net power savings due to BLI + DEP, indicating the significance of these concepts for enabling hydrogen-powered flight in civil aviation.
BIO:
Durgesh is a RET (resolution enhancement technology) engineer at Intel Corporation, and a former postdoc from MIT Gas turbine lab. She is a CFD and Systems engineering expert with demonstrated skills in electrified aircraft design, thermal systems, turbomachinery, combustion, hypersonics & nonequilibrium flows with 5+ yrs work experience at GE, NASA & MIT. She is a member of AIAA Thermophysics Technical Committee and AIAA Diversity Working Group (DWG). She also served in the AIAA working group to support FAA 2023 reauthorization for aviation and commercial space.
Durgesh is the President and Professional development chair at MIT RPA^3 (Researchers and Postdocs Association of Aeronautics and Astronautics), and Founder of the non-profit "WeLEAP Aerospace" promoting STEM diversity and talent retention. She completed her PhD from University of Minnesota and was named as one of the Women in Aerospace 2019. Her bachelors and masters degree are from Indian institute of technology (IIT) Kanpur, and she is a Ludwig-Prandtl Fellow at Max Planck Institute at Goettingen, Germany.
Gas Turbines for the Future Lunar Base
GAS TURBINE LABORATORY SEMINAR
DATE: Thursday, 3 November 2022
TIME: 4:00pm
LOCATION: 33-116
SPEAKER: Jim Kesseli, Principal Engineer, Brayton Energy
TOPIC: Gas Turbines for the Future Lunar Base
ABSTRACT:
Closed cycle gas turbines are a candidate for the future lunar power plant station. NASA’s plans call for a 40 kW-electric nuclear power plant for the early lunar base. The closed cycle Brayton is one of four options under review. This presentation will briefly outline the competitors, and unique requirements for the lunar environment, then focus on the design of the gas turbine.
BIO:
Jim has worked in the field of energy conversion systems for 40 years; contributing to advancements in small gas turbines, low emission combustion systems, and recuperators. Since forming Brayton Energy in 2004, Jim provides technical and managerial support for the company’s projects and roughly 50 engineers and technicians. Jim holds over 20 patents relating to recuperators, combustors, and gas turbines. Jim served as the ASME chair for the International Gas Turbine Institute (IGTI) Microturbines and Small Gas Turbine Committee, serving on that committee from 2002 to 2010. Jim received a BSME from WPI and an MSME from the Massachusetts Institute of Technology (MIT) in 1980.
Keys to Success in a Technical Career
GAS TURBINE LABORATORY SEMINAR
DATE: Thursday, 20 October 2022
TIME: 4:00pm
Location: 31-270
SPEAKER: Pat Cargill, GE
TOPIC: Keys to Success in a Technical Career
ABSTRACT:
Pat will speak on the Keys to Success in a Technical Career. Working on a gas turbine requires more than technical ability: skills, habits, and practices that enable an engineer to effectively contribute to a large, complex team. Pat will share tips and stories she has collected over the years (some through painful personal experiences) to give insight into what can help and what can hinder you in your engineering career on new research directions required to address the challenges.
BIO:
Pat holds a BSME from Iowa State University. She has worked for over forty years in Compression Aero, starting at Garrett (now Honeywell) in Phoenix, but mainly at GE Aviation in Cincinnati, OH. She has contributed to a range of commercial, military, and research programs. She filled both manager and senior technical leadership roles, and actively engaged in mentoring and training. Pat also has been involved in ASME/IGTI as turbomachinery committee chair and conference review chair. After retiring in 2020, Pat is now a part-time consultant with GE.
Advances in Radial Fluid Machinery
GAS TURBINE LABORATORY SEMINAR
DATE: Thursday, 15 September 2022
TIME: 4:00pm
LOCATION: 33-116
SPEAKER: Professor Zoltán Spakovszky, T. A. Wilson Professor in Aeronautics and Astronautics
TOPIC: Advances in Radial Fluid Machinery
ABSTRACT:
The characterization of internal flows in radial fluid machinery is much less advanced than that of their axial counterparts. Most of this is because jet engines, which are predominantly of axial architecture, have historically received more attention. The Gas Turbine Laboratory has embarked on a broad range of research programs related to radial machines. To give a few examples: flow instabilities in multi-stage pumps, improved performance diffusion systems in turbochargers, condensation challenges in supercritical CO2 compressors, and cavitation in rocket engine turbopumps. The talk will introduce selected problems important to industry and government agencies, illustrate the flow mechanisms and underlying concepts responsible for the shortcomings, and discuss the technological solutions. Although vastly different in nature, the projects have the following threads in common: both are rich in concepts, involve teaming and industry collaboration, and focus on problem solving rather than method development. The talk will also give a brief outlook on new research directions required to address the challenges.
Adaptive Hydraulics for Improved Centrifugal Pump Efficiency - Hilary Johnson
GAS TURBINE LAB VIRTUAL SEMINAR
DATE: Thursday, 5 May 2022
TIME: 4:00pm
SPEAKER: Hilary Johnson, PhD Student, MIT Mechanical Engineering
TOPIC: Adaptive Hydraulics for Improved Centrifugal Pump Efficiency
ABSTRACT:
Centrifugal pumps are used ubiquitously for fluid transport in industrial and municipal system. Globally, pumps consume hundreds of billions of kilowatt hours of electricity each year. Many pumping applications require operation over a broad range of pressures and flow rates, however traditional centrifugal pumps with fixed geometry are limited in their ability to adjust, resulting in significant energy losses. This research challenged the assumption that volute geometry must be static and showed that by enabling a variable volute volume, greater efficiency can be obtained over a wider operating region.
This talk presents the design and characterization of a controllable, precision, variable volute mechanism that can expand or contract to adapt to fluctuating operating conditions. Experiments support the theory-based hypothesis that adjusting the pump volume shifts the best efficiency point (BEP) creating a best efficiency range (BER). Deterministic design tools are presented, with demonstrated hydrodynamic, structural, and mechanical scalability, to enable future implementation of the variable volute technology in a variety of pump sizes for different applications. A case study is shared to demonstrate energy savings opportunities and contextualize a new operating space methodology connecting pressure and flow performance parameters with control parameters such as variable speed and variable volute.
BIOGRAPHY:
Hilary Johnson is completing her PhD in the Department of Mechanical Engineering at MIT advised by Prof. Alex Slocum. Her research integrates precision machine design and turbomachinery principles to improve operating range and efficiency for centrifugal pumps and pumping systems
Metal Foam in Aerospace: Mechanical and Aerothermal Applications - Metodi Zlatinov
Open celled metal foam is a porous structure with unique mechanical and fluid dynamics characteristics, making it ideally suited for aerospace applications ranging from light-weighting to impact protection to thermal management. These days additive manufacturing is garnering a great deal of interest with its promise of “free complexity”, but the mature technology of metal foam produced by non-additive approaches still delivers smaller feature sizes with higher reliability, lower cost and greater scalability. In this seminar we will go over some metal foam basics, and introduce a few of its applications in commercial aerospace systems.
Powering Sustainable Aviation - Sean Bradshaw
This presentation will provide an overview of Pratt & Whitney and their approach to sustainable aviation, including the product landscape, major technology themes, electrification, and sustainable fuels.
Sean Bradshaw is the technical fellow of sustainable propulsion for Pratt & Whitney. His primary focus is on the advanced technologies required for environmentally sustainable aircraft propulsion systems. This includes developing and maintaining a sustainability strategy across Pratt & Whitney that integrates with Raytheon Technologies. Sean is also engaged in Pratt & Whitney-sponsored university research on advanced technologies related to sustainable propulsion systems, and he supports the recruitment and development of core engineering talent at Pratt & Whitney.
Zero Emission Aircraft - Glenn Llewellyn
Today, aviation causes about 5% of anthropogenic global warming. If the world decarbonizes, but aviation continues to grow, aviation could be responsible for up to 25% of climate impacts by mid-century. In this talk, we will learn about Airbus’ ambition to reduce these impacts to (near-) zero. This will entail insights into the technical solutions which Airbus is developing to produce a zero-emission commercial airliner over the coming decades.
Shock Dispersion in Turbofan Ducts - Dr. Dilip Prasad
The subject of this seminar is the forward-radiated tone noise generated by a high-bypass turbofan engine at takeoff power. At this operating condition, the relative flow past the rotor tip is supersonic, resulting in the generation of a rotor-locked shock field that propagates upstream. The shocks generated by the individual blades are non-uniform owing to manufacturing and assembly tolerances, and this results in the generation of “buzz-saw” noise. Contemporary understanding of this noise mechanism is based on a purely two-dimensional perspective. In the present study, it is shown that this perspective is flawed since it does not account for the effects of wave dispersion. A theoretical framework is developed for this purpose, based on the asymptotic behavior of the wave dispersion relation for large azimuthal wavenumbers, coupled with weakly nonlinear dynamics. The framework also permits the examination of the dispersive and dissipative effects on the shock field of the inlet acoustic liner, an aspect that has received limited attention in the past. The implications of the present findings for shock noise abatement are discussed.
Current Research in Battery Thermal Management - Dr. Sonya T. Smith
Dr. Sonya T. Smith is the MLK Visiting Professor in the AeroAstro Department. This seminar will provide an overview of thermal management strategies for battery power systems in electric vehicles designed in the Applied Fluids & Thermal Research Lab (@FTERLab) at Howard university. As an example of our approach, a wavy designed thermal management system for cylindrical lithium-ion battery pack modules will be discussed.