Effects of misaligned impingement on atomization characteristics of impinging jet injector

In order to investigate the effects of misaligned impingement on the atomization characteristics of impinging jet injector, a numerical scheme to simulate cold atomization process of hypergolic propellants was established. Also atomization process with different misaligned degrees was simulated. Incompressible Navier-Stokes equations were directly solved by employing tree-based adaptive refinement algorithm. Interfaces of different fluids were captured by piecewise linear volume-of-fluid (VOF) method. The results revealed that atomization field was deflected due to misaligned impingement. When the dimensionless misaligned degree E was 1/8, the deflection angle of the atomization filed was about 9.2°, so the machining deviation should be controlled below this value. The deflected angle increased with the misaligned degree. The angle obtained by theoretical analysis was smaller than that of numerical simulation. When aligned impingement occurred, mass flow rate flux peaks of fuel and oxide were close in space and unimodal distribution of the total mass flow rate flux appeared. When misaligned impingement occurred, for the reason that partial momentums of fuel and oxide jet didn't participate in impingement, mass flow rate flux distribution of fuel and oxide interlaced and bimodal distribution of the total mass flow rate flux appeared. Mixture ratio distribution in space changed a lot. Droplet velocity distribution of aligned impingement downstream the impingement point was approximately axial symmetric while that of misaligned impingement was approximately central symmetric. Jet momentum loss caused by misaligned impingement led to poorer atomization performance. When dimensionless misaligned degree E was 1/8, Sauter mean diameter of monomethylhydrazine(MMH) increased about 4.8% and that of nitrogen tetroxide(NTO) increased about 5.8%. © 2019, Editorial Department of Journal of Aerospace Power. All right reserved.