Download or read book Unsteady Numerical Analysis of a 2 dimensional Hydrogen Fueled Air breathing Dual Mode Scramjet Engine written by Nathan John Luetke and published by . This book was released on 2006 with total page 332 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Investigation of Dual Mode Scramjet Combustor with Large Upstream Interaction written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-20 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dual-mode scramjet combustor configuration with significant upstream interaction is investigated numerically, The possibility of scaling the domain to accelerate the convergence and reduce the computational time is explored. The supersonic combustor configuration was selected to provide an understanding of key features of upstream interaction and to identify physical and numerical issues relating to modeling of dual-mode configurations. The numerical analysis was performed with vitiated air at freestream Math number of 2.5 using hydrogen as the sonic injectant. Results are presented for two-dimensional models and a three-dimensional jet-to-jet symmetric geometry. Comparisons are made with experimental results. Two-dimensional and three-dimensional results show substantial oblique shock train reaching upstream of the fuel injectors. Flow characteristics slow numerical convergence, while the upstream interaction slowly increases with further iterations. As the flow field develops, the symmetric assumption breaks down. A large separation zone develops and extends further upstream of the step. This asymmetric flow structure is not seen in the experimental data. Results obtained using a sub-scale domain (both two-dimensional and three-dimensional) qualitatively recover the flow physics obtained from full-scale simulations. All results show that numerical modeling using a scaled geometry provides good agreement with full-scale numerical results and experimental results for this configuration. This study supports the argument that numerical scaling is useful in simulating dual-mode scramjet combustor flowfields and could provide an excellent convergence acceleration technique for dual-mode simulations. Mohieldin, T. O. and Tiwari, S. N. and Reubush, David E. (Technical Monitor) Langley Research Center NAG1-2266

Download or read book Design and Multifidelity Analysis of Dual Mode Scramjet Compression System Using Coupled NPSS and Fluent Simulation written by Nandakumar Vijayakumar and published by . This book was released on 2014 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hypersonic airbreathing engines mark a potential future development of the aerospace industry and immense efforts have been taken in gaining knowledge in them for the past decades .The physical phenomenon occurring at the hypersonic flow regime makes the design and performance prediction of a scramjet engine hard. Though cuttingedge simulation tools fight their way toward accurate prediction of the environment, the time consumed by the entire process in designing and analyzing a scramjet engine and its component may be exorbitant. A multi-fidelity approach for designing a scramjet with a cruising Mach number of 6 is detailed in this research where high-order simulations are applied according to the physics involved in the component. Two state-of-the-art simulation tools were used to take the aerodynamic and propulsion disciplines into account for realistic prediction of the individual components as well as the entire scramjet. The specific goal of this research is to create a virtual environment to design and analyze a hypersonic, two-dimensional, planar inlet and isolator to check its operability for a dual-mode scramjet engine. The dual mode scramjet engine starts at a Mach number of 3.5 where it operates as a ramjet and accelerates to Mach 6 to be operated as a scramjet engine. The intercomponent interaction between the compression components with the rest of the engine is studied by varying the fidelity of the numerical simulation according to the complexity of the situation. Efforts have been taken to track the transition Mach number as it switches from ramjet to scramjet. A complete scramjet assembly was built using the Numerical Propulsion Simulation System (NPSS) and the performance of the engine was evaluated for various scenarios. Different numerical techniques were opted for varying the fidelity of the analysis with the highest fidelity consisting of 2D RANS CFD simulation. The interaction between the NPSS elements with the CFD solver is governed by the top-level assembly solver of NPSS. The importance of intercomponent interactions are discussed.The methodology used in this research for design and analysis, should add up to provide an efficient way for estimating the design and off-design operating modes of a dual mode scramjet engine.

Download or read book Numerical Analysis of Mixture Formation and Combustion in a Hydrogen Direct Injection Internal Combustion Engine written by Udo Gerke and published by Cuvillier Verlag. This book was released on 2008-02-05 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present work investigates the mixture formation and combustion process of a direct-injection (DI) hydrogen internal combustion engine by means of three-dimensional numerical simulation. The study specifies details on the validity of turbulence models, combustion models as well as aspects on the definition of hydrogen-air burning velocities with respect to hydrogen IC engine applications. Results of homogeneous, stratified and multi-injection engine operation covering premixed, partially premixed and non-premixed combustion of hydrogen are presented. Results of the numerical simulations are validated using data of experimental analysis from parallel works, employing a one-cylinder research engine and a research engine with optical access. As a fundamental contribution to combustion modelling of hydrogen IC engines, a new correlation for laminar burning velocities of hydrogen-air mixtures at engine-relevant conditions is derived from measurements of premixed outwards propagating flames conducted in a single-cylinder compression machine. Numerical results of the direct-injection mixture formation give a detailed understanding of the interrelation between injection timing and the degree of mixture homogenisation. A favourable agreement between the computed fuel concentration and results of Planar Laser Induced Fluorescence (PLIF) measurements is reported for various injection timings. Different two-equation turbulence models, a Shear Stress Transport (SST) model and a k-ε model based on Renormalisation Group (RNG) theory as well as a Reynolds Stress Model (RSM) are discussed. The impact of the models on the level of turbulent kinetic energy proves to be of major importance. State-of-the-art turbulent combustion models on the basis of turbulent flame speed closure (TFC) and on the basis of a flame surface density approach, the Extended Coherent Flame Model (ECFM), are examined. The models are adapted to hydrogen internal combustion engines and are interfaced to the established three-dimensional flow field solver ANSYS CFX within the framework of the international research project HyICE. Two different approaches are investigated as input for the laminar burning velocities of hydrogen. Firstly, flame speed data are computed with a kinetic mechanism. Secondly, an existing experimentally derived laminar flame speed correlation is extended to rich air/fuel equivalence ratios (λ 1) and is compared to measurements conducted within the present work. In general, the TFC-models show a satisfying agreement for DI operating points compared to experimental data, when mixing computations are conducted with the SST turbulence model. Also, port fuel injection (PFI) operating points demonstrate a good performance with these models, however, the constant model prefactor (multiplier for the closure of turbulent flame speed) has to be defined individually for PFI and DI computations. This effect might be caused by the dissimilar sources of turbulence for the two engine types (PFI and DI) which cannot be adequately predicted by the turbulence models. Combustion computations on the basis of mixture results obtained by the RNG-model generally underrate the level of turbulence intensity for stratified operation points, effecting too weak rates of heat release. The ECFM combustion model shows a satisfying predictability for the PFI case using a constant model prefactor. Computations of DI operating points with this model, however, require a readjustment of the prefactor for each operating point in order to match experimental results. Regarding turbulent combustion, the hydrogen laminar flame speed is recognised to be the crucial quantity for the employed modelling approaches. Since direct-injection hydrogen engines in the stratified case engender a wide range of equivalence ratios, fundamental data for the laminar flame speed has to be provided as a model input within the entire boundaries of ignition limits. A lack of experimental data of laminar flame speed at engine-relevant conditions (high pressure, high temperature) is noticed. In order to perform a detailed study on hydrogen burning velocities, a single-cylinder compression machine is selected to conduct flame speed measurements of hydrogen-air mixtures at ignition temperatures and pressures up to T = 700 K and p = 45 bar, considering air/fuel equivalence ratios between λ = 0.4 and 2.8. Flame front velocities are acquired by means of optical methods using OH-chemiluminescence and thermodynamic, multi-zone evaluation of pressure traces. In comparison to data of laminar flame speed derived from reaction mechanisms and flame speed correlations found in literature, the experimental results show increased burning velocities due to flame front wrinkling caused by hydrodynamic and thermo-diffusive instabilities. a href="http://ec.europa.eu/research/transport/news/article_5199_en.html" EU Transport Research

Download or read book Numerical Study of Combustion of Hydrogen and Ethylene in a Two dimensional Dual mode Scramjet Combustor written by Robert A. Carson and published by . This book was released on 2004 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Simulation of Vitiation Effects on a Hydrogen fueled Dual mode Scramjet written by and published by . This book was released on 2010 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Numerical Analysis Study of the Reacting Flow in a Scramjet Airbreathing Engine written by Marc Núñez Corbacho and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Scramjet engines are the fastest form of propulsion that has been conceived, being capable offlying in a flight regime above Mach number 5. The concept of scramjet engine is not recent,as its development started more than half a century ago. However, a scramjet vehicle has onlyflown three times (by NASA), being the last one in 2004 and reaching a Mach number of 10.The working principle of a scramjet engine is the same as the subsonic engines: compressing,combusting and expanding air to produce thrust. Nevertheless, scramjet engines do not havemoving parts such a compressor or a turbine, as the flow at hypersonic speed is compresseddirectly by the inlet and the combustion is held in supersonic regime.In this study, a parametric model for the combustor and nozzle of a scramjet engine has beendeveloped, focusing in the combustion process. Under quasi-one-dimensional steady flowconditions, the properties at the exit of the combustor and nozzle are computed by calculatingthe composition of the gas at the combustor for different conditions of temperature, fuel ratio,pressure and velocity.Also, in order to assess the performance of the engine, a simplified inlet model is assumed.Finally, the results of this document are compared with those of other studies. Some possibleimprovements of the study are also included.

Download or read book NASA SP written by and published by . This book was released on 1992 with total page 654 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Air Breathing Engines and Aerospace Propulsion written by B. N. Raghunandan and published by Allied Publishers. This book was released on 2004 with total page 752 pages. Available in PDF, EPUB and Kindle. Book excerpt: Contributed papers presented at the 7th National Conference on Air Breathing Engines and Aerospace Propulsion, hosted at I.I.T., Kanpur.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 892 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Hypersonic Airbreathing Propulsion written by William H. Heiser and published by AIAA. This book was released on 1994 with total page 632 pages. Available in PDF, EPUB and Kindle. Book excerpt: An almost entirely self-contained engineering textbook primarily for use in undergraduate and graduate courses in airbreathing propulsion. It provides a broad and basic introduction to the elements needed to work in the field as it develops and grows. Homework problems are provided for almost every individual subject. An extensive array of PC-based user-friendly computer programs is provided in order to facilitate repetitious and/or complex calculations. Annotation copyright by Book News, Inc., Portland, OR

Download or read book Numerical Simulation of Mode Transition in a Hydrogen fueled Scramjet written by Manan Ajay Vyas and published by . This book was released on 2009 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The Wind-US computational fluid dynamics (CFD) flow solver was used to simulate dual-mode direct-connect ramjet/scramjet engine flowpath tests conducted in the University of Virginia (UVa) Supersonic Combustion Facility (SCF). The objective was to develop a computational capability within Wind-US to aid current hypersonic research and provide insight to flow as well as chemistry details that are not resolved by instruments available."--Leaf iv.

Download or read book Numerical Simulation of UVA Ramjet scramjet Hypersonic Engine with Hydrogen air Combustion Using Wind US written by Vishal Anand Bhagwandin and published by . This book was released on 2008 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The internal flowpath of University of Virginia's Mach 5, direct-connect, dual-mode scramjet engine was simulated using Wind-US, a density-based Reynolds-Averaged Navier-Stokes flow solver. Detailed flowfield simulation results are directly compared to experimental data to evaluate the accuracy of the numerical model and to provide insight into the flowfield behavior."--Leaf iii.

Download or read book Unstart Phenomenology of a Dual mode Scramjet Subject to Time varying Fuel Input written by Logan P. Riley and published by . This book was released on 2019 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt: The efficiency of the MOR-based representations of the combustor dynamics are evaluated in terms of the reconstruction error for a given level of data compression (order reduction). Importantly, two methods are proposed from which to infer higher-order dynamics using the reconstruction errors. The first method, relies directly on the reduced-order reconstruction to identify large-magnitude error regions indicative of higher-order dynamics. A second approach is presented in which the MOR-based filters are applied to the entire three-dimensional domain for which brute force computation of reconstruction error is computationally infeasible. DMD, in particular, is shown to encode information of the time-mean and higher-order dynamics within the dominant mode. Consequently, the difference between the time-mean field and DMD mode is shown to identify regions which feature non-linear temporal flowfield variations. The three-dimensional MOR analysis isolates spanwise gradients associated with isolator corner flow and shear layers developing downstream of the cavity and the backward-facing steps. To facilitate MOR analysis of the full, three-dimensional simulation data, variables are partitioned into separate decompositions to mitigate computation cost. For DMD, it is shown that partitioning the observables of interest into separate MOR decompositions produces similar but not identical dynamics, as inferred from the DMD eigenspectra. This suggests caution when applying these techniques to high-dimensional three-dimensional datasets if the goal is to compare the low-order representations of different variables. Finally, a time-local variant of the DMD method is applied to filter the statistically unsteady scramjet flowfield. The method shows improved reconstruction performance over standard DMD while still capturing the primary dynamic structure associated with upper wall separation. Such MOR decompositions are thus shown to provide a reasonable filter to the leading dynamics of the statistically unsteady combustor which may further facilitate control system development and optimal sensor selection and placement.

Download or read book A Numerical Investigation of Flowfield Modification in High speed Airbreathing Inlets Using Energy Deposition written by Matthew Flynn Rohweder and published by . This book was released on 2010 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Energy deposition in front of dual-mode ram/scramjet engines is numerically investigated utilizing two-dimensional CFD for its potential to modify inlet/isolator flow-fields for engine start/unstart control and for its general potential for generating large-scale flow-field modification in such flows. A simplified (high Mach number) constant-area duct geometry is initially defined in order to test the feasibility of the concept; the results from this initial investigation demonstrates possible beneficial effects of depositing energy upstream of a thermally choked duct in terms of causing massive changes in flow patterns, including the reestablishment of supersonic flow throughout the duct. This study is followed by the definition of a realistic high-speed engine domain focusing on the lower external and internal engine side of a hypersonic vehicle. A quasi-one-dimensional solver is constructed and used to establish approximate understanding of thermal choking limits in the defined geometry. A CFD investigation of this actual engine geometry is performed in which heating blocks are used to simulate fuel-air combustion in the engine combustor. Actual choking limits are established and a base-line case defined with substantial (choked flow) upstream interaction. A range of energy deposition cases are then run in order to assess the use of upstream energy deposition for facilititating restarting an unstarted engine, mitigating unstart, and generating large-scale flow-field modification in the isolator/inlet of a dual-mode ram/scramjet engine. Results indicate that, although the ability to actually increase performance of an unstarted engine through the use of upstream energy deposition is minimal, there is indication that the use of such a technique for generating a "virtual cowl" and/or a "virtual" isolator (including throats, etc.) is possible"--Abstract, leaf iii

Download or read book International Aerospace Abstracts written by and published by . This book was released on 1998 with total page 920 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Dual Mode Scramjet written by Ryan Timothy Milligan and published by . This book was released on 2009 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerical analysis was performed on a Dual-Mode Scramjet isolator-combustor. Preliminary analysis was performed to form a baseline geometry. Another study validated the results of a 2D model compared to a 3D model. Stable combustion was shown at two different flight conditions, M=3.0 and M=2.5. A marginal 5% decrease in stream thrust was shown by introducing a 50/50 mix of methane and ethylene. Based on the results of the preliminary analysis, detailed geometry analysis was performed on the 3D baseline geometry. Adding a new set of cavity feeding injectors increased the overall stream thrust and the equivalence ratio in the cavity. Using less fuel than the baseline configuration, revealed a 6.4% increase in stream thrust and an 11% increase in combustion efficiency by placing the second stage injector further upstream. Future analysis includes combining the cavity feeding with closer injector placement, which is expected to yield even better results.