Evaluation of source term treatments for high-speed reacting flows

1998 ◽  
Author(s):  
J. Clutter ◽  
Wei Shyy
Keyword(s):  
High Speed ◽  
Source Term ◽  
Reacting Flows

Numerical Simulation of Heat Transfer and Fluid Dynamics in Supersonic Chemically Reacting Flows

2010 ◽  
Author(s):  
Alexander M. Molchanov ◽  
Anna A. Arsentyeva
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
High Speed ◽  
Stokes Equations ◽  
Order Approximation ◽  
Reacting Flows ◽  
Supersonic Combustion ◽  
Special Method ◽  
Chemically Reacting Flows ◽  
Chemically Reacting

An implicit fully coupled numerical method for modeling of chemically reacting flows is presented. Favre averaged Navier-Stokes equations of multi-component gas mixture with nonequilibrium chemical reactions using Arrhenius chemistry are applied. A special method of splitting convective fluxes is introduced. This method allows for using spatially second-order approximation in the main flow region and of first-order approximation in regions with discontinuities. To consider the effects of high-speed compressibility on turbulence the author suggests a correction for the model, which is linearly dependent on Mach turbulent number. For the validation of the code the described numerical procedures are applied to a series of flow and heat and mass transfer problems. These include supersonic combustion of hydrogen in a vitiated air, chemically reacting flow through fluid rocket nozzle, afterburning of fluid and solid rocket plumes, fluid dynamics and convective heat transfer in convergent-divergent nozzle. Comparison of the simulation with available experimental data showed a good agreement for the above problems.

Investigation of a Stiff-Integrator Scheme for High-Speed Reacting Flows

2000 ◽  
Author(s):  
Lance D. Woolley ◽  
Douglas A. Schwer ◽  
Russell L. Daines
Keyword(s):  
Time Scales ◽  
High Speed ◽  
Reaction Rates ◽  
Reacting Flows ◽  
Operator Technique ◽  
Detailed Chemical Kinetics ◽  
Time Step ◽  
Kinetics Models ◽  
Split Operator ◽  
Air Chemistry

Abstract Improvements in the modeling of high-speed reacting propulsion flowfields are sought through the coupling of a stiff integrator to determine chemical reaction rates with a multidimensional CFD code. Detailed chemical kinetics models usually have significantly shorter reaction time scales than the fluid time scales, resulting in stiff governing equations and robustness issues. The present work investigates the application of a stiff ordinary differential equation solver, coupled to a diagonalized alternating-direction implicit scheme to decouple the governing time scales. This coupled ODE-ADI split-operator technique is applied to two high-speed reacting flows using hydrogen/air chemistry. The results from the stiff integrator method are compared to the traditional coupled approach utilizing 8- and 18-step kinetics models. Time-step choice, robustness, and comparison of results between the different solution methods are discussed, along with CPU times.

Source Term Based Modeling of Rotating Cavitation in Turbopumps

2018 ◽  
Author(s):  
A. G. Vermes ◽  
C. Lettieri
Keyword(s):  
Price Competition ◽  
High Speed ◽  
Large Scale ◽  
Source Term ◽  
Experimental Testing ◽  
Rocket Engine ◽  
Computational Cost ◽  
Flow Coefficient ◽  
Rocket Engines ◽  
Launch Vehicles

The recent growth of private options in launch vehicles has substantially raised price competition in the space launch market. This has increased the need to deliver reliable launch vehicles at reduced engine development cost, and has led to increased industrial interest in reduced order models. Large-scale liquid rocket engines require high-speed turbopumps to inject cryogenic propellants into the combustion chamber. These pumps can experience cavitation instabilities even when operating near design conditions. Of particular concern is rotating cavitation, which is characterized by an asymmetric cavity rotating at the pump inlet, which can cause severe vibration, breaking of the pump and loss of the mission. Despite much work in the field, there are limited guidelines to avoid rotating cavitation during design and its occurrence is often assessed through costly experimental testing. This paper presents a source term based model for stability assessment of rocket engine turbopumps. The approach utilizes mass and momentum source terms to model cavities and hydrodynamic blockage in inviscid, single-phase numerical calculations, reducing the computational cost of the calculations by an order of magnitude compared to traditional numerical methods. Comparison of the results from the model with experiments and high-fidelity calculations indicates agreement of the head coefficient and cavity blockage within 0.26% and 5% respectively. The computations capture rotating cavitation in a 2D inducer at the expected flow coefficient and cavitation number. The mechanism of formation and propagation of the instability is correctly reproduced.

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