The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform

Dimitri N Mavris - One of the best experts on this subject based on the ideXlab platform.

  • Enhanced Robust Design Simulation and Application to Engine Cycle and Technology Design
    Journal of Engineering for Gas Turbines and Power, 2017
    Co-Authors: Jonathan S. Sands, Brian Kestner, Christopher Perullo, Dimitri N Mavris
    Abstract:

    Increased computing power has enabled designers to efficiently perform robust design analyses of Engine systems. Traditional, filtered Monte Carlo methods involve creating surrogate model representations of a physics-based model in order to rapidly generate tens of thousands of model responses as design and technology input parameters are randomly varied within user-defined distributions. The downside to this approach is that the designer is often faced with a large design space, requiring significant postprocessing to arrive at probabilities of meeting design requirements. This research enhances the traditional, filtered Monte Carlo robust design approach by regressing surrogate responses of joint confidence intervals for metric responses of interest. Fitting surrogate responses of probabilistic confidence intervals rather than the raw response data changes the problem the Engineer is able to answer. Using the new approach, the question can be better phrased in terms of the probability of meeting certain requirements. A more traditional approach does not have the ability to include confidence in the process without significant postprocessing. The process is demonstrated using a turboshaft Engine modeled using the numerical propulsion system simulation (NPSS) program. The new robust design process enables the designer to account for probabilistic impacts of both technology and design variables, resulting in the selection of an Engine Cycle that is robust to requirements and technology uncertainty.

  • Improved Pareto Optimal Engine Cycle Designs Through the Use of a New Pareto Quality Indicator
    48th AIAA ASME SAE ASEE Joint Propulsion Conference & Exhibit, 2012
    Co-Authors: Nicholas Molino, Jonathan S. Sands, Scott J. Duncan, Eriks Osvalds, Dimitri N Mavris
    Abstract:

    A new quality indicator for Pareto efficient frontiers has been developed in order to map desired Pareto optimal set attributes to a single metric. This new Pareto quality metric was tested to see if it could be effectively utilized along with Response Surface Methodology (RSM) techniques to tune the parameter settings of multiobjective optimization schemes. As a working example, the parameter tuning was applied to a multiobjective genetic algorithm optimizing the Engine Cycle design of a geared turbofan with N+2 level technology on a 300 passenger commercial aircraft. The Environmental Design Space (EDS) tool, which analyzes aircraft performance, source noise, and exhaust emissions, was used for the Cycle design. The goal of the multiobjective optimization was to simultaneously minimize total fuel burn and cumulative noise for a specified mission profile. This research has concluded that tuning the parameter settings of an optimizer can provide significant benefits in generating Pareto optimal solutions, especially when executed on an Engine Cycle design. The Pareto quality indicator developed has shown promise in assisting the parameter tuning effort, but must be refined through further research and development.

  • Hybrid Wing Body Engine Cycle Design Exploration for Boundary Layer Ingesting (BLI) Propulsion Systems Under Design Uncertainty
    48th AIAA ASME SAE ASEE Joint Propulsion Conference & Exhibit, 2012
    Co-Authors: Jonathan S. Sands, Brian Kestner, Jonathan C. Gladin, Dimitri N Mavris
    Abstract:

    of the concept. The current paper presents a modeling approach that allows for the modeling of BLI at multiple design points and throughout the mission operating envelope. Furthermore, the paper presents a probabilistic Engine Cycle design space study for a 300 passenger HWB aircraft using the EDS design tool that explores the impacts of the various physical assumptions on the system level impacts. The results show that the system is particularly sensitive to the level of total pressure drop at the fan face. An Engine sizing study shows that the level of assumed losses incurred by the Engine has a large eect on the resultant size of the Engine as well as on the performance of the sized Engine at other assumed loss levels.

  • Surrogate Modeling for Simultaneous Engine Cycle and Technology Optimization for Next Generation Subsonic Aircraft
    Volume 1: Aircraft Engine; Ceramics; Coal Biomass and Alternative Fuels; Controls Diagnostics and Instrumentation, 2012
    Co-Authors: Brian Kestner, Jeff Schutte, Jimmy C. Tai, Christopher Perullo, Dimitri N Mavris
    Abstract:

    This paper presents an Engine sizing and Cycle selection study of ultra high bypass ratio Engines applied to a subsonic commercial aircraft in the N+2 (2025) timeframe. NASA has created the Environmentally Responsible Aviation (ERA) project to serve as a technology transition bridge between fundamental research (TRL 1–4) and potential commercial application (TRL 7). Specifically, ERA is focused on subsonic transport technologies that could reach TRL 6 by 2020 and can be integrated into an advanced vehicle concept to simultaneously meet the ERA project metrics for noise, emissions, and fuel burn. An important variable in exploring the technology trade space is the selection of the optimal Engine Cycle for use on the advanced aircraft. Previous literature demonstrated the Cycle optimization using a design of experiments (DOE) to explore the Engine Cycle design space for a pre-defined technology package. However, since the optimal Engine Cycle is dependent upon the specific technology package, this process would have to be repeated to ensure optimal performance for each technology package. With more than 80 technologies to be analyzed, the combinatorial space of technology packages is enormous. As a result, executing a DOE to find the optimum Engine Cycle for each technology package is infeasible. To address this issue, it is proposed to use surrogate models that encompass the Engine Cycle and technology design space to enable fast and accurate optimization of the Engine Cycle for any given technology package.This paper describes the generation and analysis of surrogate models used for technology assessment and Cycle optimization of an ultra high bypass geared turbofan Engine architecture. The first study in the paper shows that a single surrogate model can be used to accurately simulate both a technology and Cycle design space. To demonstrate the proposed surrogate modeling approach, the Cycle design space for three different technology packages was analyzed. This study demonstrated that when an optimal Cycle is found within the constrained interior of a design space, the surrogate modeling approach is quite accurate. The study also established that the surrogate models can also be used to assess potential Cycles at the boundaries or even outside of the region for which they were trained.© 2012 ASME

  • Effects of Boundary Layer Ingesting (BLI) Propulsion Systems on Engine Cycle Selection and HWB Vehicle Sizing
    50th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition, 2012
    Co-Authors: Jonathan C. Gladin, Jonathan Sands, Brian Kestner, Dimitri N Mavris
    Abstract:

    A methodology for analyzing the boundary layer ingestion technology on a hybrid wing body aircraft has been developed using a simplified boundary layer analysis based on computation fluid dynamic results. With certain assumptions, a method for calculating the boundary layer velocity profiles across the flight envelope was shown using a log-wake velocity profile. This boundary layer profile was integrated over the surface of an assumed “D-shape” inlet to produce the inlet total pressure, temperature, and the ratio of the area averaged Mach number to the free-stream Mach number. The resulting curves were used within the EDS multi-disciplinary environment to analyze an HWB aircraft with BLI and other N+2 technologies over a range of Cycle design parameters and for varying inlet aspect ratios. Aerothermodynamic Engine Cycle design explorations are performed that show that the candidate Engine Cycle selection that minimizes design mission fuel burn depends greatly on the assumed negative impacts BLI has on the Engine performance.

José A. Camberos - One of the best experts on this subject based on the ideXlab platform.

  • airbreathing rotating detonation wave Engine Cycle analysis
    Aerospace Science and Technology, 2013
    Co-Authors: Eric M Braun, Donald R. Wilson, Frank K Lu, José A. Camberos
    Abstract:

    Abstract A Cycle analysis model for an airbreathing, rotating detonation wave Engine (RDE) is presented. The Engine consists of a steady inlet system with an isolator which delivers air into an annular combustor. A detonation wave continuously rotates around the combustor with side relief as the flow expands towards the nozzle. A model for the side relief is used to find the pressure distribution around the combustor. Air and fuel enter the combustor when the rarefaction wave pressure behind the detonation front drops to the inlet supply pressure. To create a stable RDE, the inlet pressure is matched in a convergence process with the average combustor pressure by increasing the annulus channel radial width with respect to the isolator channel. Performance of this Engine is considered using several parametric studies and compared with rocket-mode computational results. A hydrogen–air RDE reaches a specific impulse of 3800 s and can reach a flight speed of Mach 5.

  • airbreathing rotating detonation wave Engine Cycle analysis
    Aerospace Science and Technology, 2013
    Co-Authors: Eric M Braun, Donald R. Wilson, Frank K Lu, José A. Camberos
    Abstract:

    Abstract A Cycle analysis model for an airbreathing, rotating detonation wave Engine (RDE) is presented. The Engine consists of a steady inlet system with an isolator which delivers air into an annular combustor. A detonation wave continuously rotates around the combustor with side relief as the flow expands towards the nozzle. A model for the side relief is used to find the pressure distribution around the combustor. Air and fuel enter the combustor when the rarefaction wave pressure behind the detonation front drops to the inlet supply pressure. To create a stable RDE, the inlet pressure is matched in a convergence process with the average combustor pressure by increasing the annulus channel radial width with respect to the isolator channel. Performance of this Engine is considered using several parametric studies and compared with rocket-mode computational results. A hydrogen–air RDE reaches a specific impulse of 3800 s and can reach a flight speed of Mach 5.

J.a. Caton - One of the best experts on this subject based on the ideXlab platform.

  • Thermodynamic Considerations Related to Knock: Results From an Engine Cycle Simulation
    Journal of Engineering for Gas Turbines and Power, 2018
    Co-Authors: J.a. Caton
    Abstract:

    The design and development of high efficiency spark-ignition Engines continues to be limited by the consideration of knock. Although the topic of spark knock has been the subject of comprehensive research since the early 1900s, little has been reported on the coupling of the Engine thermodynamics and knock. This work uses an Engine Cycle simulation together with a submodel for the knock phenomena to explore these connections. First, the autoignition characteristics as represented by a recent (2014) Arrhenius expression for the reaction time of the end gases are examined for a range of temperatures and pressures. In spite of the exponential dependence on temperature, pressure appears to dominate the ignition time for the conditions examined. Higher pressures (and higher temperatures) tend to enhance the potential for knock. Second, knock is determined as function of Engine design and operating parameters. The trends are consistent with expectations, and the results provide a systematic presentation of knock occurrence. Engine parameters explored include compression ratio, Engine speed, inlet pressure, start of combustion, heat transfer, and exhaust gas recirculation (EGR). Changes of cylinder pressures and temperatures of the unburned zone as Engine parameters were varied are shown to be directly responsible for the changes of the knock characteristics.

  • Thermodynamic Considerations Related to Knock: Results From an Engine Cycle Simulation
    Volume 1: Large Bore Engines; Fuels; Advanced Combustion, 2017
    Co-Authors: J.a. Caton
    Abstract:

    The design and development of high efficiency spark-ignition Engines continues to be limited by the consideration of knock. Although the topic of spark knock has been the subject of comprehensive research since the early 1900s, little has been reported on the coupling of the Engine thermodynamics and knock. This work uses an Engine Cycle simulation together with a sub-model for the knock phenomena to explore these connections. First, the autoignition characteristics as represented by a recent (2014) Arrhenius expression for the reaction time of the end gases is examined for a range of temperatures and pressures. In spite of the exponential dependence on temperature, pressure appears to dominate the ignition time for the conditions examined. Higher pressures (and higher temperatures) tend to enhance the potential for knock. Second, knock is determined as functions of Engine design and operating parameters. The trends are consistent with expectations, and the results provide a systematic presentation of knock occurrence. Engine parameters explored include compression ratio, Engine speed, inlet pressure, start of combustion, heat transfer, and exhaust gas recirculation (EGR). Changes of cylinder pressures and temperatures of the unburned zone as Engine parameters were varied are shown to be directly responsible for the changes of the knock characteristics.

  • Comparisons of Instructional and Complete Versions of Thermodynamic Engine Cycle Simulations for Spark-Ignition Engines:
    International Journal of Mechanical Engineering Education, 2001
    Co-Authors: J.a. Caton
    Abstract:

    Instructional and complete versions of thermodynamics Engine Cycle simulations for spark-ignition Engines were compared. The instructional version of the Cycle simulation used constant specific heats as compared to using variable properties and composition for the complete simulation. For the proper selection of constant properties, the global Engine performance parameters obtained from the instructional version of the Cycle simulation were in close agreement to the values obtained from using the complete version of the simulation. The specific values of items such as maximum pressure and temperature, however, were not exactly duplicated. Examples are given based on a commercial, spark-ignition Engine. For the cases studied here, the brake power and thermal efficiency as obtained from the constant property version of the simulation (for a ratio of specific heats of 1.30 and a gas constant of 0.287 kJ/kg K) were in excellent agreement with the same parameters from the complete simulation for a range of ope...

Eric M Braun - One of the best experts on this subject based on the ideXlab platform.

  • airbreathing rotating detonation wave Engine Cycle analysis
    Aerospace Science and Technology, 2013
    Co-Authors: Eric M Braun, Donald R. Wilson, Frank K Lu, José A. Camberos
    Abstract:

    Abstract A Cycle analysis model for an airbreathing, rotating detonation wave Engine (RDE) is presented. The Engine consists of a steady inlet system with an isolator which delivers air into an annular combustor. A detonation wave continuously rotates around the combustor with side relief as the flow expands towards the nozzle. A model for the side relief is used to find the pressure distribution around the combustor. Air and fuel enter the combustor when the rarefaction wave pressure behind the detonation front drops to the inlet supply pressure. To create a stable RDE, the inlet pressure is matched in a convergence process with the average combustor pressure by increasing the annulus channel radial width with respect to the isolator channel. Performance of this Engine is considered using several parametric studies and compared with rocket-mode computational results. A hydrogen–air RDE reaches a specific impulse of 3800 s and can reach a flight speed of Mach 5.

  • airbreathing rotating detonation wave Engine Cycle analysis
    Aerospace Science and Technology, 2013
    Co-Authors: Eric M Braun, Donald R. Wilson, Frank K Lu, José A. Camberos
    Abstract:

    Abstract A Cycle analysis model for an airbreathing, rotating detonation wave Engine (RDE) is presented. The Engine consists of a steady inlet system with an isolator which delivers air into an annular combustor. A detonation wave continuously rotates around the combustor with side relief as the flow expands towards the nozzle. A model for the side relief is used to find the pressure distribution around the combustor. Air and fuel enter the combustor when the rarefaction wave pressure behind the detonation front drops to the inlet supply pressure. To create a stable RDE, the inlet pressure is matched in a convergence process with the average combustor pressure by increasing the annulus channel radial width with respect to the isolator channel. Performance of this Engine is considered using several parametric studies and compared with rocket-mode computational results. A hydrogen–air RDE reaches a specific impulse of 3800 s and can reach a flight speed of Mach 5.

Iskander Tlili - One of the best experts on this subject based on the ideXlab platform.

  • Thermodynamic Study on Optimal Solar Stirling Engine Cycle Taking Into Account the Irreversibilities Effects
    Energy Procedia, 2012
    Co-Authors: Iskander Tlili
    Abstract:

    Abstract Looking for an Engine Cycle with height output, multi-source of energy and less polluting pushes to reconsider the Stirling Cycle. Several prototypes of Engine were produced (Ford-Philips 4-215, Ross yoke, GPU-3... etc), but their performances remain weak compared with other types of internal combustion Engine. In order to increase their performances and to analyze their operations, a numerical program of simulation taking into account thermal and mechanical losses was developed and a study of optimization of the design parameters was elaborated. The program which was applied to GPU-3 prototype of the General Motor gave results very close to the experimental results and leads to the optimization of the operating conditions. It also leads to the determination of the optimal values of the geometrical and physical design parameters of the prototype and to the increase of its performances as long as the working gas pressure is maintained acceptable of the working gas in the Engine.