In the present work, the influence of the turbulence model on the numerical predictions of supersonic combustion of hydrogen in a model combustor is investigated. Three dimensional, compressible, turbulent, reacting flow calculations using the Shear Stress Transport (SST) κ - ω model have been carried out. The results are compared with earlier results obtained using the Spalart-Allmaras model. The effect of detailed chemistry on the predictions of heat release and combustion efficiency is also investigated for one injection scheme. The calculations show that the mixing and hence the heat release is over predicted by the SA model. Whereas, the peak values for pressure and temperature are predicted better by the SST κ - ω model. This investigation demonstrates the importance of the use of a two equation turbulence model over a one equation model for studying such complex flow phenomena. Copyright © 2009, Inderscience Publishers.

Viswanathan T. Babu

Department of Mechanical Engineering

Combustion efficiencies

Complex flow

Detailed chemistry

Heat release

Injection schemes

MODEL COMBUSTOR

Numerical predictions

Numerical simulations

ONE-EQUATION MODEL

Peak values

Pressure and temperature

Reacting flows

SHEAR-STRESS TRANSPORT

SPALART-ALLMARAS MODEL

Supersonic combustion

Two-equation turbulence models

Atmospheric temperature

combustion

Computer simulation languages

Forecasting

Hydrogen

Simulators

smoke

SUBMARINE GEOPHYSICS

Thermochemistry

Turbulence models

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

A comparison of the numerical predictions of the supersonic combustion of Hydrogen using the S-A and SST k – ω models

Progress in Computational Fluid Dynamics

In this numerical study, supersonic combustion of kerosene in three model combustor configurations is investigated. To this end, 3-D, compressible, turbulent, nonreacting, and reacting flow calculations with a single step chemistry model have been carried out. For the nonreacting flow calculations, the droplet diameter distribution at different axial locations, variation of the Sauter mean diameter, and the mixing efficiency for three injection pressures are presented and discussed. In addition, the effect of turbulent dispersion on the mixing efficiency is studied using a stochastic model in conjunction with the two-equation shear stress transport κ-ω turbulence model. For the reacting flow calculations, contours of heat release and axial velocity at several axial locations are used to identify regions of heat release inside the combustor. Combustion efficiency predicted by the present results is compared with earlier predictions for all the combustor models. Furthermore, the predicted variation of static pressure along the combustor top wall is compared with experimental data reported in the literature. Calculations show that the penetration and spreading of the fuel increases with an increase in the injection pressure. Predicted values of the combustion efficiency are more realistic when the spray model is used for modelling the injection of the fuel. The importance of the mixing process, especially for a liquid fuel such as kerosene, on the prediction of heat release is discussed in detail.

Journal of Propulsion and Power

Mixing and combustion characteristics of kerosene In a model supersonic combustor

In this numerical study, the influence of chemistry models on the predictions of supersonic combustion in a model combustor is investigated. To this end, 3D, compressible, turbulent, reacting flow calculations with a detailed chemistry model (with 37 reactions and 9 species) and the Spalart-Allmaras turbulence model have been carried out. These results are compared with earlier results obtained using single step chemistry. Hydrogen is used as the fuel and three fuel injection schemes, namely, strut, staged (i.e., strut and wall) and wall injection, are considered to evaluate the impact of the chemistry models on the flow field predictions. Predictions of the mass fractions of major species, minor species, dimensionless stagnation temperature, dimensionless static pressure rise and thrust percentage along the combustor length are presented and discussed. Overall performance metrics such as mixing efficiency and combustion efficiency are used to draw inferences on the nature (whether mixing- or kinetic-controlled) and the completeness of the combustion process. The predicted values of the dimensionless wall static pressure are compared with experimental data reported in the literature. The calculations show that multi step chemistry predicts higher and more wide spread heat release than what is predicted by single step chemistry. In addition, it is also shown that multi step chemistry predicts intricate details of the combustion process such as the ignition distance and induction distance. © 2009 The Combustion Institute.

Combustion and Flame

Investigation of the effect of chemistry models on the numerical predictions of the supersonic combustion of hydrogen

Numerical simulations of the three-dimensional reacting flow in a staged supersonic combustor (Mach 2.5) have been carried out. The combustor has a strut for the first stage and wall-mounted injectors for the second stage (S. Tomioka, A. Murakami, K. Kudo, and T. Mitani, "Combustion Tests of a Staged Supersonic Combustor with a Strut," Journal of Propulsion and Power, Vol. 17, No. 2, 2001, pp. 293-300). The Spalart-Allmaras model has been used for modeling turbulence and single-step finite-rate chemistry has been used for modeling the H 2/Air kinetics. The grid has been refined to achieve average value for wall y + less than 20. The predicted static-pressure profile along the centerline of the combustor is compared with experimental data for different injection schemes. Details of the flowfield inside the combustor as well as variation of mixing efficiency, combustion efficiency, and total pressure loss along the length are presented and discussed.

Numerical simulation of three-dimensional reacting flow in a model supersonic combustor

42nd AIAA/ASME/SAE/ASEE Joint Propulsion Conference &amp; Exhibit

On the effect of Schmidt and Prandtl Numbers in the Numerical Predictions of Supersonic Combustion

43rd AIAA Aerospace Sciences Meeting and Exhibit

Comparison of First and Second Order Turbulence Models for a Jet/3D Ramp Combination in Supersonic Flow

42nd AIAA Aerospace Sciences Meeting and Exhibit

Modeling of High Speed Reacting Flows: Established Practices and Future Challenges

A comparison of the numerical predictions of the supersonic combustion of Hydrogen using the S-A and SST κ - ω models

Journal	Progress in Computational Fluid Dynamics
ISSN	14684349
Open Access	No