Research On The Effect Of Aspect Ratio On 2-D Hypersonic Inlet Performance

In this paper, computational fluid dynamics simulations were performed on 2-D hypersonic inlets'three-dimensional flow fields by NAPA. The inlets were transform- ed with isolator aspect ratio of 1.0, 3.0, 6.0, and 9.0 in equal windward area and equal windward height. Inner flow character of flow fields were analyzed at design point Mach number 6.0 and some other different Mach number with different back pressure. This investigation would provide some reference for the 2-D hypersonic design and optimize. The performance of the isolators with four aspect ratios was simulated as follow and the effect of aspect ratio on isolator performance was presented at Mach 3.2 and Mach 2.0.The investigation of the effect of aspect ratio on 2-D hypersonic inlets perfor- mance showed that: With sufficient side width, the flow character and performance on external compress ramp were almost same. For the different height of boundary layer on the external compress ramp affected by aspect ratio, the flow mass ratio and total pressure recovery on the external compress ramp would fall with the raise of aspect ratio in case of equal windward area . For the flow quantity near side wall changed with aspect ratio, the flow character and performance in internal compress ramp and isolator were changed. When the aspect ratio of the inlet was small, three-dimensional flow near the side wall would affect the performance of the inlet in evidence. When the inlets endure peak back pressure, the value of the peak back pressures would fall and the position where shock trains started would move to the exit point of the isolator. Aspect ratios also affect the total pressure recovery and the Mach number in the exit of the inlet. The start ability of the inlet with isolator aspect ratio of 1 became worse.The investigation of the effect of aspect ratio on isolator performance showed that: The value of the peak back pressures would fall with the aspect ratio increase; The position where shock trains started would move to the exit point of the isolator when the isolator endure the same pressure, and the started poison would move to the import point of the isolator. The total pressure recovery would decrease at Mach3.2, and the changes of the total pressure recovery were not evidence at Mach 2.0. Aspect ratios also affect the Mach number in the exit of the inlet, but the changes of the temperature were not evidence.