Markus Lempke

Numerical Investigation of the HyShot Supersonic Combustion Configuration

A multivariate assumed PDF approach together with finite-rate chemistry is used for the simulation of the HyShot supersonic combustion configuration. Because the combustor entrance conditions of scramjets at low flight Mach numbers (Ma 8) are close to the ignition limit of hydrogen air mixtures, detailed kinetic schemes are required and an accurate simulation of temperature and temperature fluctuations is essential. In the present paper, experiments of the HyShot supersonic combustion configuration performed at the High

Parallelization and Performance Analysis of an Implicit Compressible Combustion Code for Aerospace Applications

The compressible, implicit combustion code TASCOM3D is used with and without the spray module SPRAYSIM for different aerospace applications. A number of such cases and analysis of the performance of the code on massively parallel systems will be given. These include supersonic combustion simulations of a complete scramjet model, a model rocket combustor fueled with gaseous oxygen and hydrogen as well as two multiphase simulations. The evaporation of kerosene in a preheated, pressurized channel and the spray combustion in a LOX/GH2 rocket combustor require an additional numerical tool to account for the liquid phase. Droplet propagation and evaporation is computed by the research code SPRAYSIM. Furthermore investigations with respect to the performance of the employed numerical codes are addressed. With respect to TASCOM3D the influence of block sizing on the performance is investigated intensively both in terms of weak and strong scaling. The strong scaling performance of SPRAYSIM is investigated for both multiphase simulations. It will be shown that both codes show a nearly ideal behavior.

Numerical Investigations of Model Scramjet Combustors

In the present paper different types of scramjet (supersonic combustion ramjet) combustors are investigated. Thereby the main difference between the combustors is the way of injecting the fuel into the combustion chamber. The first investigated concept of fuel injection is the injection by strut injectors. Here the injection of fuel is realized by a lobed strut that is located in the middle of the combustion chamber. The second concept for fuel supply is the wall injection of hydrogen. Here the fuel is injected by several holes in the wall of the combustor. Both concepts of fuel injection have different advantages and disadvantages which are explained in detail. Although different performance parameters for both scramjet combustors are introduced this paper will not compare the different techniques among each other. Because of the high Reynolds numbers in scramjet combustors, the need to resolve the boundary layers and the necessity of detailed chemistry, the simulation of scramjets is extremely CPU time demanding.

Numerical Simulations of Rocket Combustion Chambers on Massively Parallel Systems

The compressible, implicit combustion code TASCOM3D is used for the simulation of rocket combustion chambers. Coupled Euler-Lagrange simulations for a subcritical operated model rocket combustor at 5 bar pressure are performed. A quarter of the rectangular combustor is discretized for three-dimensional RANS simulations. Three spray simulations with different initial droplet size distributions are performed. Simulation results exhibit only limited dependency on the initial droplet size distribution. Finally, performance of TASCOM3D on HERMIT and HORNET is compared. A different scaling behavior on both machines with respect to local block size variations is observed.

Euler-Lagrange Simulation of a LOx/H2 Model Combustor with Single Shear Coaxial Injector

In this paper a mixed Euler-Lagrange approach is used for a 3D simulation of a LOX/H2 model rocket combustor with a single shear coaxial injector. The specific test case presented is the MASCOTTE combustor at 10 bar pressure in the so called A-10 configuration. The simulation of the gas phase is conducted with the scientific code TASCOM3D which works in an Eulerian mode while the liquid fuel droplets are treated by the scientific code SPRAYSIM in a Lagrangian framework. The two codes and the coupling mechanisms are explained and results of a preliminary simulation will be presented. At the end an outlook is given focusing on how to obtain an even more accurate representation of the experiment in subsequent simulations. Finally some comments on the computational costs of the calculations and the performance of the two codes on the NEC SX-9 are given.

Delayed Detached Eddy Simulation of a Rotationally Symmetric Supersonic Jet

A Delayed Detached Eddy Simulation (DDES) of a rotationally symmetric free jet is performed with the scientific in-house code TASCOM3D (Turbulent All Speed Combustion Multigrid 3D). The DDES is a hybrid RANS/LES method that employs the RANS approach in the near-wall region and LES modeling otherwise. The transition is achieved by filtering depending on the grid spacing. To preserve the RANS mode in the boundary layer an appropriate blending function is used. The investigated experiment is a supersonic Ma 1.8 jet exiting a nozzle into ambient conditions. The simulation results for the axial velocity, temperature, density and density fluctuations are compared to measured values. Several simulations have been performed to analyze the effect of the modeling constant C DES , grid refinement, and the addition of artificial fluctuations in the boundary layer that are not created inherently in the used approach. The overall agreement between experiment and simulation is quite satisfying although the transition is apparently predicted too far upstream in all simulations.

TASCOM3D: A Scientific Code for Compressible Reactive Flows

The numerical framework of the scientific code TASCOM3D (Turbulent All Speed Combustion Multigrid Solver) is introduced and its application for compressible flows is presented. The in-house code is developed over more than two decades and has been used successfully to simulate compressible reacting and non-reacting flows. It describes reacting flows by solving the full compressible Navier-Stokes, species and turbulence transport equations. As turbulence closure different two-equation turbulence models are implemented and turbulence-chemistry interactions are taken into account by an assumed PDF approach. As demonstration of applications of TASCOM3D two different investigations are presented: simulations of a model scramjet combustor and a cryogenic rocket combustor. Furthermore the performance of TASCOM3D on the NEC SX-9 system is analysed. The investigation points out the challenges and problems in HPC and may serve other researchers as comparison and assistance to achieve good performance on vector processor based architectures.