Exploration of combustion instability triggering using Large Eddy Simulation of a multiple injector liquid rocket engine

Abstract

et al.. Exploration of combustion instability triggering using Large Eddy Simulation of a multiple injector Liquid Rocket Engine. Combustion and Flame, Elsevier, 2016, 169, pp. a b s t r a c tThis article explores the possibility of analyzing combustion instabilities in liquid rocket engines by making use of Large Eddy Simulations (LES). Calculations are carried out for a complete small-scale rocket engine, including the injection manifold thrust chamber and nozzle outlet. The engine comprises 42 coaxial injectors feeding the combustion chamber with gaseous hydrogen and liquid oxygen and it operates at supercritical pressures with a maximum thermal power of 80 MW. The objective of the study is to predict the occurrence of transverse high-frequency combustion instabilities by comparing two operating points featuring different levels of acoustic activity. The LES compares favorably with the experiment for the stable load point and exhibits a nonlinearly unstable transverse mode for the experimentally unstable operating condition. A detailed analysis of the instability retrieves the experimental data in terms of spectral features. It is also found that modifications of the flame structures and of the global combustion region configuration have similarities with those observed in recent model scale experiments. It is shown that the overall acoustic activity mainly results from the combination of one transverse and one radial mode of the chamber, which are also strongly coupled with the oxidizer injectors.

Comparison of energy-, pressure- and enthalpy-based approaches for modeling supercritical flows

“…where P mechanical is the pressure used in the transport equations and P eos is the pressure derived from the thermodynamic scheme. This method has recently been used in multiple rocket-like configurations to investigate combustion and acoustic instabilities [9,55,56,57]. Ma et al [58] This approach provides some improvements but does not totally alleviate the issue [29,59,8].…”

Study of flame response to transverse acoustic modes from the LES of a 42-injector rocket engine

“…A typical run is performed in parallel on 16,384 cores so that the restitution time is reasonable despite the significant computational burden. 1 A limit cycle is reached in the LES and the dynamics of the system is computed over a period of 7.5 ms. A detailed presentation of this simulation is given in [15] and the aim of the present work is to perform an in-depth analysis of the limit cycle and analyze the flame response. For this purpose, 200 snapshots of the full 3D solution were saved over 2 ms of the limit cycle (between 5 and 7 ms), which corresponds to 330 Gb of data.…”

“…Indeed, high fidelity modeling strategies such as Large-Eddy Simulation (LES) have had considerable successes in predicting unstable operating points for gas turbine combustors [6,7] or gaseous coaxial injectors [8][9][10] . With the recent development of LES for transcritical flows [11][12][13][14] , high-pressure liquid rocket engine stability can now be numerically studied [15] . Nevertheless, these methods are usually too cumbersome to allow explorations of the whole range of operating conditions.…”

Coupling heat transfer and large eddy simulation for combustion instability prediction in a swirl burner

“…Differences in frequency or amplitude may occur when the temperature field and the FTF in the simulation only partially match those in the experiment, but the simulation can usually be used for further investigation of the thermoacoustic mode. There are numerous studies of combustion instabilities that illustrate that LES with adiabatic walls can show a reasonable agreement with experiments: the study on a lean-premixed swirl combustor by Huang et al [8] , the LES-studies on the PRECCIN-STA configuration [9][10][11] , the massively parallel LES of a realistic helicopter combustion chamber by Wolf et al [12] , LESs of model rocket combustors (Garby et al [13] , Urbano et al [14] ) or the LESstudies of bluff-body stabilized flames by Li et al [15] and Ghani et al [16] .…”

“…• Type 1: Adiabatic walls: the majority of recent LESs simply consider the walls to be adiabatic [8][9][10][11][12][13][14][15][16][19][20][21][22] .…”