Dimensionless analysis of the unstart boundary for 2D mixed hypersonic inlets

Abstract

Abstract Inlet unstart boundary is one of the most important issues of the hypersonic inlet and is also the foundation of the protection control of a scramjet. To solve this problem, the 2D internal steady flow of a 2D mixed internal/external compression hypersonic inlet was numerically simulated at different freestream conditions and backpressures with a RANS (Reynolds-Averaged Navier-Stokes) solver using a RNG (Renormalisation Group) k-ε turbulence model, and two different inlet unstart phenomena were analysed. The dimensional analysis method was introduced to find the essence variables describing the inlet unstart boundary based on “numerical experimental” data in this paper. The dimensionless pressure ratios of the forebody and isolator were analysed respectively. The results show that the unstart boundary of the 2D mixed hypersonic inlet is determined by M0, α and Re0. Pressure ratio π increases with M0 increasing, and it increases firstly and decreases then with α increasing. Pressure ratio π increases with Re0 increasing. Re0 (Re0 < 2 × 107) has a major effect on π and Re0 (Re0 > 2×107) has little effect on π.