Parameterization and optimization design of a two-dimensional axisymmetric hypersonic inlet

Optimization method, as a promising way to improve inlet aerodynamic performance, has received increasing attention. The present research is undertaken to design a two-dimensional axisymmetric hypersonic inlet using parametric optimization. The inlet configuration is parameterized and optimized in consideration of total pressure recovery and starting performance. A Pareto front is obtained by solving the multi-objective optimization problem. Then, the flow structures of the optimized inlets are analyzed and the starting performances are evaluated. Results show that the total pressure loss mainly occurs in the internal contraction section, especially near the inlet entrance, and therefore the total pressure recovery coefficient can be greatly improved by decreasing external compression. As a result, the guidance for designing high-performance inlets is concluded. Besides, it is found that as the internal contraction ratio increases, the inlet starting ability becomes worse, which attributes to the larger separation bubble at the inlet entrance. Finally, the total pressure recovery coefficient and the starting Mach number of the optimized inlets are obtained, which can be a reference for engineering design.

Magnetohydrodynamic Control of Hypersonic Separation Flows

Magnetohydrodynamic (MHD) control of hypersonic laminar separation flows is investigated in this paper. A series of numerical simulations over various geometry configurations, namely, a compression corner and a double wedge ramp hypersonic inlet, have been conducted by application of an external electromagnetic field. Results show that the performance of MHD separation flow control is mainly determined by flow acceleration of the Lorentz force directed in the streamwise direction. The Joule heating term always brings negative effects on the MHD separation flow control and increased the static pressure locally, where the electromagnetic field is applied. With an external electromagnetic field applied, the low velocity fluid in the boundary layer can be accelerated. Moreover, there exists a best location for the MHD zone to be applied and completely eliminate the separation of the flow from the surface.

Potential of Micro-Vortex Generators in Enhancing the Quality of Flow in a Hypersonic Inlet-Isolator

The rush to be the first to demonstrate a practical hypersonic cruise missile has never been more frantic among the world’s superpowers, especially since China and India have also announced their own programme. The main hurdle for safe hypersonic flight is the severe shock wave-boundary layer interaction (SWBLI) that could induce flow separation. The separation could lead to inlet unstart and also structural damage at the flow re-attachment point. The simplest method to control these phenomena is by using passive flow control devices such as micro-vortex generator (MVG). The MVG is typically sized in the range of sub-boundary layer and the vortex generated can induce an early transition to turbulence thus avoiding or reducing the impact of flow separation. Many studies have been published with regard to MVG, but most were done in low supersonic speed and not in the hypersonic flow regime. In the current study, the MVG array was placed strategically at various locations on a hypersonic inlet-isolator representative geometry. The MVG has been proven to be very effective in eliminating or reducing the size of flow separation thus reducing the associated peak pressure at the re-attachment point.