Turbulent Combustion Model Applicantion In The Supersonic Flow Field

Because of the high strategic importance and application value, the hypersonic vehicle has become a hot topic in the field of aerospace; Supersonic combustion problem as a difficult polint in the process of supersonic aircraft research, also causes the wide attention from all over the world. The supersonic combustor has complex working process, incoming flow residence time is very short, and in this short period of time it needed to complete the injection, ignition and combustion. The liquid fuel combustion need to consider the droplet atomization, collision, crushing and other two-phase flow problems. These works make the supersonic combustion research particularly difficult. With the development of the computer technology, the numerical calculation has been an extremely valuable and cost-effective engineering tool. It can get the detailed information on the flow field in a short time, and provide basis for the study of supersonic combustion. Based on this background, the paper respectively simulated the gas fuel and liquid fuel supersonic combustion and discussed in the applicability of the different turbulence combustion model in the supersonic combustion flow field.Firstly, the DLR hydrogen supersonic combustion engine is seen as the research object,and simulated by 2d model and 3d model in the cold flow field. After comparing velocity and pressure distribution, it is concluded that the 3d has a better simulation result than 2d. The 3d density solver and pressure solver result is consistent in DLR engine. In the numerical simulation of combustion, the eddy dissipation concept model, finite rate model, eddy dissipation model and the flamelet model has been used. In these models, the eddy dissipation concept model, finite rate model and flamelet model has considered the different reaction mechanism. By comparing the temperature distribution and velocity distribution, the flamelet model has the best simulation result and the smallest amount of calculation, it is more suitable in the DLR hydrogen supersonic combustion engine.Then, in order to calculation of liquid injection problem, the supersonic jet water is simulated to discuss the applicability of the different secondary break-up model under the supersonic speed. By contrast with the injection height and injection distribution, the secondary break-up model can’t be ignored and the KH-RT model is most suitable for the simulation of the supersonic jet. The impact of the unsteady flow field and the collision model to the jet water also is discussed. The experiment that the jet-to-air momentum flux ratios equal 7 and10 is simulated, too.Finally, according to above conclusion, picked suitable simulation method is calculated in the supersonic combustion issue of the liquid fuel. The spatial distribution of the liquid fuel and the temperature distribution are similar to the flame photo and schlieren image in the experiment. The simulated wall pressure trend is consisted with the experiment, the calculated result is reasonable.