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REST (Rocket Engine Stability initiative) is a European initiative to coordinate and share research activities and to improve the understanding of combustion instability in Liquid Propellant Rocket engines. This is done in different kinds of workshops, e.g. modeling workshops. In such modeling workshops, the participants are invited to treat common test cases for benchmarking their tools. REST test case HF-10 is a numerical test case defining a set up for the calculation of a methane coaxial flame which all participants were invited to use with their respective codes and models. The test case was based on an engine demonstrator defined in the frame of the DLR SFB TRR 40 and can be considered as representative for a full scale rocket engine. The demonstrator uses coaxial injection elements burning LOX CH4 at 100bar. In order to keep the numerical effort limited, one singe element is calculated for a cross section of representative size and periodic boundary conditions. A steady state flow field and 3 excited calculations were demanded as test cases: CH4 modulation with +-10% @ 5kHz LOX modulation with +-10% @ 5kHz and 1kHz The participants contributed as many of the calculations as they were willing to. The participants performing the test cases are both industrial and scientific institutions, working on commercial and in-house codes. Each participant used his own numerical approaches such as LES, URANS. Different chemistry models and different numerical schemes were employed. Most results which are compiled in this paper are also presented in detail in individual publications. The synthesis presented here permits to compare the works on a global level. This is of particular interest due to the variety of numerical approaches and models employed. The results have been post-processed in a comparable manner using prescribed views and color maps by all participants. This eases the direct visual comparison. The focus is set on flame shape, reaction rates and temperature. Due to the common post processing, the results can be presented in a clear manner both for mean and phase averaged solution. As far as possible, the results are presented side by side to permit an easy comparison. Some differences in flame structure, flame dynamics and other parameters are visible and highlight the particularities and capabilities of the modelling.

This work presents the experimental investigation of heat fluxes through the walls of a reduced-scale rocket motor using hydrogen and oxygen as propellants. The engine is water cooled so that it ca...

There is a need for experimental data in conditions representative injection in rocket engines to validate or initiate droplet formation models used in numerical simulations. A new cryogenic vessel was built upon the MASCOTTE test bench to study the atomization of a single oxygen liquid jet, under non-reactive conditions, with simultaneous optical diagnostics. A test plan was built to explore the fiber-type regime occurring in liquid rocket injection systems, with a fixed Reynolds number and a large range of Weber number and momentum flux ratio, compared to existing studies. High-speed images are used to describe qualitatively the fiber-type regime and to visualize were droplets are present, in order to prepare the drop-size measurements. Phase Doppler Interferometry is used to measure the size and velocity of droplets produced by atomization of a liquid oxygen jet by a co-flowing gas. Droplet size and velocity measurements were performed with a PDI close to the nozzle exit in order to provide data on droplets produced by the primary atomization process, which can be useful for numerical simulations initialisation. The radial evolutions of the axial velocity and of the drop size distribution show similar trends as observed in the literature. The axial velocity is investigated for different operating conditions with helium or nitrogen as atomizing gas, showing an increase on the side of the spray. The radial evolution of the droplet size shows a translation of the drop size distribution on the edge of the spray towards the smaller sizes, indicating that the biggest liquid elements stay close to the LOX jet.

International audience; A diagnosis benchmark was developed for the MASCOTTE test bench of ONERA/CNES. It consists of a CARINS Simulator of the bench, model-based fault diagnosis algorithms and firing tests results. The objective of this work was to demonstrate alternatives to the classical redline monitoring strategy used on the bench. A simplified model of the cooling circuit of the test bench was built and used to apply a parameter identification detection method and a Kalman filter. The diagnosis flags are obtained through analysis of the residuals via CUSUM tests. This article shows the results obtained and proposes an example of methodology to identify and validate performances of new diagnostic strategies.

In today’ s context of budget cuts and strong competition, reliability, short delays, and cost reduction have become critical issues for combustion device designers, who must seek out new approaches. In this paper, we address the main design issues and the processes involved in liquid-propellant combustion devices. A modern approach emphasizing the key role research that will become increasingly important in combustion device design and optimization is presented. As an illustration, a research program on high-pressure liquid oxygen/hydrogen injection and combustion is described.

The combustion process in a high-pressure gaseous methane/gaseous oxygen rocket model combustor was investigated by means of optical and laser spectroscopic measurements as well as numerical simulations. Thecombustorwasoperatedatapressureof1.0MPaandattwomixture ratios(O/F=1and2). OH ∗ chemiluminescenceimagingwasappliedfor a qualitative analysis of the position and shape of the §ame brush. For quantitative results, coherent anti-Stokes Raman spectroscopy (CARS) was applied to measure the spatial temperature distribution inside the combustion chamber. H2 and H2O molecules were probed simultaneously using two synchronized broadband CARS setup. Temperatures were derived from the H2and H2O single-shot CARS spectra. Furthermore, the Transported Partially Stirred Reactor (TPaSR) model has been employed for simulations at the same operating conditions. The comparison of the numerical simulations to the experimental temperature distributions shows already qualitative agreement although further improvements are still needed.

This article describes the on-going results of a fault diagnosis benchmark for a cryogenic rocket engine demonstrator. The benchmark consists in the use of classical model- based fault diagnosis methods to monitor the status of the cooling circuit of the MASCOTTE cryogenic bench. The algorithms developed are validated on real data from the last 2014 firing campaign (ATAC campaign). The objective of this demonstration is to find practical diagnosis alternatives to classical redline providing more flexible means of data exploitation in real time and for post processing.