Numerical study of the performance of a model scramjet engine

2020

Recently few countries have tested the scramjet engine for aerospace application. The challenge was to achieve complete combustion at supersonic flow and to generate the required thrust for given inlet flow conditions. Research is still going on so as to attain the necessary mixing and efficient combustion inside a scramjet combustor. Performance parameter like total pressure loss across the scramjet combustor is one of the crucial parameters and has to be minimized. Factors such as equivalence ratio, inlet flow conditions affect the combustion process and hence the useful thrust. Also, the fuel injection configuration plays a vital role in mixing and thus on the performance of a scramjet combustor. Over the recent years numerical simulation has been acknowledged as a promising tool for investigation of Scramjet flow. In this work, the investigation of effect of injector configuration has been carried out using a commercial CFD tool. Validation of initial numerical results is done w...

2014

Scramjet engines can decrease the cost of access-to-space systems. One-dimensional solvers can be used to rapidly analyse many scramjet engine configurations to maximise performance. This paper uses an inviscid, quasi-one-dimensional, chemical equilibrium solver to examine the effects of combusting using constant area, constant pressure, constant Mach number or constant temperature processes. Constant area combustion typically produces the highest specific impulse for given combustor entrance conditions. When a maximum engine pressure constraint is imposed the constant pressure process becomes more effective. This work shows that if combustion occurs at constant area until the maximum pressure is reached, then continued using a constant pressure process, the required intake compression and contraction ratios can be decreased by 53% and 35% respectively from the constant pressure case. This decrease results in improved starting characteristics for a negligible cost to performance. The effect of maximum engine pressure on performance is examined and it is shown that there is little benefit from increasing intake compression ratios above 60, or maximum engine pressure over a factor of 150 above the freestream pressure. Nomenclature A Area c Speed of sound CA Constant area CM Constant Mach number CP Constant pressure CT Constant temperature f Fuel-air ratio F un Uninstalled thrust g Acceleration due to gravity at the Earth's surface

Ramjets can be particularly useful in applications requiring a small and simple engine for high speed use, such as missiles, while weapon designers are looking to use ramjet technology in artillery shells to give added range. A scramjet propulsion system is a hypersonic air-breathing engine in which heat addition, due to combustion of fuel and air, occurs in the flow that is supersonic relative to the engine. By contrast, the airflow in a pure scramjet remains supersonic throughout the combustion process and does not require a choking mechanism. In general any scramjet engine begins with Mach number of 5. In order maintain some reduction in speed we use turbojet engines which propel from 3.2 to 4.2 Mach and from there the ramjet picks upon and starts to propel to start the scramjet. The design for a scramjet engine is carried out in this paper considering the only entry designs and numerical analysis is carried out using ANSYS FLUENT software. For the Analysis Two dimensional geometry created in the GAMBIT data taking from the public domain literature survey followed by suitable mesh was carry out. By giving the suitable boundary conditions Numerical analysis carried out using FLUENT. Analyzed results will be comparing with the experimental work for the selection of Aeromechanical features.

Aerospace Science and Technology, 2019

A SCRAMJET engine typically has multiple transverse fuel injectors with a flame holder. In this study, we consider a two-jet SCRAMJET engine design configuration that uses the low speed recirculation region created by a backward facing step as a flame holder. The effect of spacing between the transverse fuel injectors on the performance of a SCRAMJET engine has been studied using cold-flow simulations. The position of the leading jet is kept fixed at the end of the recirculation zone as suggested by previous studies and the second jet is placed at various locations downstream in the distinct flow regions formed behind the leading jet. It is assumed that the two jets are identical in dimensions and flow. The spacing between the jets is expected to play a significant role in determine the performance of the SCRAMJET engine. Three-dimensional simulations have been performed, using Menter's SST model in our in-house parallel 3-D RANS unstructured grid CFD solver. The mixing of inlet air and the injected air-fuel in such a SCRAMJET configuration is augmented by the interaction of the transverse under-expanded jet with the incoming supersonic cross-flow through the generation of strong streamwise vorticity. The performance and mixing of the combustor have been quantified for each of the distinct configurations. It is observed that they are indeed affected by the spacing between the jets. From the results presented in this paper, the optimal location for the second jet is at the end of the zone over which the lateral momentum of the first jet is dominant in affecting the jet penetration into the streamwise flow.

2016

The flowfield characteristics of a relatively small quasiaxisymmetric scramjet vehicle at a Mach 6 flight condition have been investigated numerically. To this end, three-dimensional, compressible, turbulent, reacting flow calculations with a finite rate chemistry model consisting of 33 reactions and 13 species and two-equation SST k-ω RANS model have been performed. Hydrogen is used as the fuel and the injection pressure of fuel is varied from 1 to 7 MPa in order to study the effect of the injection pressure on the flowfields in the scramjet model. The combustion length has been found to decrease as the injection pressure increases. However, rather little thrust gain has been achieved by combustion heat release in the present configurations.

Scramjet Design Lecture

This presentation is part of Dr. Sarosh's lecture series on hypersonic propulsion design. In this lecture, Dr. Sarosh has provided the step-by-step procedure for undertaking the scramjet engine's analytical and computational aerothermodynamic design. More importantly, this lecture series includes discrete solutions for two types of scramjet systems namely the constant pressure and pressure gain combustors.

2012

Scramjet inlet design remains as a key aspect for hypersonic flight. To assess the inlet design, the performance parameters namely; aircapture ratio, total pressure efficiency, inlet drag coefficient, and kinetic energy efficiency are evaluated and analysed. In the current study comparison of performance parameters is carried out by performing numerical computation of 2-D turbulent flow field for four different scramjet inlet geometries with two different free stream Mach number (M=4 and 5). The numerical computation is performed with the help of Femlab’s finite element method tool “Comsol Multiphysics” using the “Turbulent High Mach Number Flow” module provided in it.

47th AIAA Aerospace Sciences Meeting including The New Horizons Forum and Aerospace Exposition, 2009

The ramjet and the scramjet are promising air breathing engine concepts that are capable of powering any aircraft in the Mach number range of 3 to 10. This research explores the inverse design of a tip-to-tail dual mode ramjet-scramjet engine that is derived from the exact solution of simplified supersonic and hypersonic flow fields. Through the coupled use of the exact solutions of shock waves in an ideal gas, and the exact representations of planar and axisymmetric geometric shapes, a series of elementary configurations are developed and analyzed. The design process is accomplished through the use of specially developed subroutines, programmed in FORTRAN, to manipulate and assemble these elementary configurations into completed engine configurations. The elementary shapes of interest to this study include the starshaped leading edges, the caret-shaped inlets, and cylindrical combustors, convergent and divergent nozzles, and plug nozzle after-bodies. This research effort is built on the authors' previous works on elementary aerodynamic shape generation, integration and analysis. As part of this effort a FORTRAN code is developed. As its output, the design code generates the engine configuration and analyzes its aerodynamic performance. Further, the algorithms used to evaluate the resulting engine performance characteristics, such as the Isp, the thrust, and maximum operating temperatures, are based on empirical engineering correlations and strict geometric principles. In general, the code developed as part of this research effort was used to conduct the following studies: Generate propulsion systems configurations from prescribed 2-D shock waves; Evaluate the resulting engine geometric characteristics; Evaluate the thrust performance of the engine, and; Identify the design parameters that affect the engine's overall performance and shape. The outcome of this research can be classified in the following two categories. First, the propulsion system design and assembly process led to the discovery of engineering parameters that directly influence the aerodynamic performance of the resulting configuration. These parameters were manipulated to generate configurations with superior thrust and Isp characteristics. Second, routines were developed that led to the design and analysis of a morphing ramjet-to-scramjet configuration.

A numerical insight was accomplished to optimize the scramjet combustor configuration based on orthogonal experimental design. Parametric modeling of combustor configurations was performed by the orthogonal array with 13 factors at 3 levels. Numerical simulations were proceeded by k-ε standard turbulence model and eddy-dissipation model in the combustion process. The performance indexes of combustion efficiency, total pressure recovery coefficient and thrust gain coefficient were evaluated. Detailed comparison with the effect of the factors on the performance was also carried out to demonstrate the main factors and determine the optimal configuration. The analysis of the extreme differences of the factors indicates that the main factors affecting combustion efficiency were the length of the wedge, the length depth ratio of the cavity, the depth of the cavity, and the length of the expanding section; The main factors affecting total pressure recovery coefficient are the angle of the primary combustor, the length of the expanding section, and the thickness of the strut; The main factors affecting thrust gain coefficient are the thickness of the strut, the length of the expanding section, and the angle of the secondary combustor. Validation of the optimal configuration is then confirmed that its performance is higher than the rest of the configurations, with the combustion efficiency of 0.915 and the total pressure recovery coefficient of 0.486, which are 31.5% and 65.9% higher than the experimental results, respectively.

Philosophie der Musik, 2024

Die Musikphilosophie Theodor W. Adornos hat die musikästhetische Diskussion in Deutschland über viele Jahrzehnte bestimmt. Das Buch lotet dieses Erbe aus, indem es die Grundgedanken von Adornos am Paradigma der Musik entwickelten Ästhetischen Theorie für Formen der Musik ausbuchstabiert, die Adorno selbst nicht im Blick hatte. Die Texte knüpfen hierbei einerseits an Adornos Erbe an, befragen aber zugleich kritisch die normative Einengung auf bestimmte Arten von Musik. Bekanntermaßen waren Adornos Urteile über den Jazz und auch die Popmusik vernichtend. Mit und gegen Adorno versucht das Buch, auf die ästhetischen Potenziale des Jazz wie der Popmusik zu pochen. Dies geschieht, indem anhand von acht Grundbegriffen (von "Begriff" über "Dialektik" und "Kritik" bis "Gattung") Überlegungen zur Musik im Spannungsfeld der Künste entwickelt und entfaltet werden. Die Kapitel des Buches können dabei im Zusammenhang oder für sich gelesen werden.