The effects of diamond injector angles on flow structures at various Mach numbers

Abstract

Numerical simulations of a three dimensional diamond jet interaction flowfield at various diamond injector half angles into a supersonic crossflow were presented in this thesis. The numerical study was performed to improve the understanding of the flame holding potential by extending the numerical database envelop to include different injector half angles and examine the flow at Mach 2 and Mach 5. The configuration of a diamond injector shape was found to reduce the flow separation upstream, and produce an attached shock at the initial freestream interaction and the injection fluid has an increased field penetration as compared to circular injectors. The CFD studies were also aimed at providing additional information on the uses of multiple injectors for flow control. The numerical runs were performed with diamond injectors at half angles of 10° and 20° at a freestream Mach number of 5. The transverse counter-rotating pair of vortices found in the 15° does not form within the 10° and 20° cases at freestream Mach number 5. The 10° case had a barrel shock that became streamlined in the lateral direction. The 20° barrel shock had a very large spanwise expansion and became streamlined in the transverse direction. In both cases the trailing edge of their barrel shocks did not form the flat “V” shape, as found in the baseline case. At Mach 2 the 10° and 15° cases both formed the flat “V” shape at the trailing edge of the barrel shocks, and formed the transverse counter rotating vortex pairs. The 10° multiple injector case successfully showed the interaction shocks forming into a larger planer shock downstream of the injectors. The swept 15° case produced interaction shocks that were too weak to properly form a planar shock downstream. This planar shock has potential for flow control. Depending on the angle of incidence of the injector fluid with the freestream flow and the half angle of the diamond injector, the planar shocks will form further upstream or downstream of the injector.