Effects of Flow Spillage Strategies on the Aerodynamic Characteristics of Diverterless Hypersonic Inlets

This paper compares the aerodynamic characteristics of a central-spillage diverterless hypersonic inlet (i.e., bump inlet, Form 1) with a side-spillage inlet (Form 2) under on/off design conditions when faced with non-uniform inflow. Both forms are designed for a flight Mach number of 6.0 and a cruise altitude of 24.0 km. Numerical methods are introduced and validated. Integrated design results indicate that based on identical contraction ratios, Form 2 is 27.8% lower in height, 28.3% shorter in length, and 34.4% smaller in the windward projection area than Form 1. This provides the evidence that the side-spillage strategy will suppress the external drag less. Then, the aerodynamic performance is investigated under various upstream/downstream boundary conditions (inflow speed range: Mach 2.0 similar to 6.0; backpressure fluctuation range: 1 similar to 110.0 times the freestream static pressure). The evaluation methods for non-uniform flow fields are first introduced in this paper. Form 2 has a relatively stronger shock system, which allows it to suppress 4.52% more of the pressure fluctuation from the downstream combustion chamber than Form 1. The inlet start margin is widened by approximately 250% due to the self-adaptive flow spillage ability established by the side-spillage strategy. Furthermore, the compression efficiency, internal shock system, spillage ability, etc., are analyzed in detail. In summary, the side-spillage flow organization strategy has better potential for designing wide-ranging air-breathing flight vehicles.

Automated summary

This study compares the aerodynamic characteristics of two hypersonic inlets under non-uniform inflow conditions and finds that the side-spillage inlet has smaller dimensions and a stronger shock system, enabling better suppression of pressure fluctuations from the downstream combustion chamber, as well as a larger start margin.