The Influence Mechanism Of Angle-cutting Wave System On Supersonic Flow Process

The scramjet is a new type of air-breathing propulsion device, which has remarkableperformance and great potential superiority, and has a good prospect in the field of militaryaviation in the future. A number of experimental, theoretical and computational studies havebeen conducted to explore the Scramjet techniques in the past decades. The residence time of fuelstayed in the supersonic combustion ramjet combustion chamber is in milliseconds, so the problems tocomplete a stable and efficient combustion in a very short period of time is to be solved.The influence of angle-cutting shock and expansion waves on supersonic flow process issystematic studied in this paper, background to the mechanism and Law of cavity flame holder effect onthe supersonic flow.The main contents include, the influence of unconventional tab and cavity onsupersonic flow process, fuel injection and the coupling effect between shock wave generated by fuel andunconventional cavity and fuel diffusion process. The results showed that,Because of the complexity of the combustion chamber geometry, the unstructured meshes are moresuitable for meshing than the structured meshes. Taking pressure gradient adaptive on the mesh according tothe results, the meshes in partial complex flow area will increase and field distribution in this area is moredetailed and precise.The supersonic flow past a tab with a certain sweep angle in the combustion chamber with a tab, theintensity of the shock wave is gradually enhanced along the leading edge of the tab from front to back. In thecombustion chamber with a tab containing forward-swept structures, the compression waves will generate atthe surface of the sidewall, and the highest pressure is also at the sidewall surface. The angle cutting shockwave will be slightly forward due to the structure of forward-swept tab, and it will be slightly backwardbecause of the structure of the forward-swept tab.The generation and reflection of oblique shock wave isrelated to the front inclination of the tab.In the combustor flow field with a unconventional cavity, because the direction of the velocity will deflect when the supersonic airflow past the wave system including the shock and expansion waves systemdeflection,the velocity after the angle cutting shock and expansion waves system generated by the3D cavitystructure will have a horizontal component, leading to the vortex structure in the cavity change, this willmake mainstream flow and combustion process more complex.The flow field in four unconventional cavitycombustion chambers is symmetrical distributed in the transverse direction.Compared with the closed cavity,the open cavity has a relatively lower resistance coefficient, a longer cavity residence time and a higher massexchange rate between the mainstream and the flow in the cavity. So it is more suitable for open cavity to be aflame holder.