Experimental study of high-speed air intake performance by side clearance

Abstract

Japan Aerospace Exploration Agency (JAXA) and universities plan the “High Mach Integrated Control Experiment” (HIMICO), which is a hypersonic flight test by JAXA's S-520 sounding rocket. The experimental aircraft for HIMICO is powered by a ramjet engine, whose intake is a rectangular mixed compression type with a design Mach number of 5.In this research, the effects of the side clearance (SC) on the intake performance are investigated at Mach 3.4 by supersonic wind tunnel tests. The side clearances are thin slits between the 2nd and 3rd ramps and sidewalls, which is provided for driving the variable geometry intake. Three types of models with different SC widths were compared. As the results, it is found that the 2nd ramp SC, which is located upstream of the throat, causes the performance deterioration and the 3rd ramp SC, which is located downstream of the throat can expand the starting range. Hybrid SC which has only the 3rd ramp SC obtains sufficient Mass Capture Ratio (MCR) and maintains the start condition over a wider nozzle throat height range due to the air bleed from the 3rd ramp SC. However, the performance of Hybrid SC deteriorates when adding the sideslip angle, β=5°, because of a leakage from the bleed slit located between the 2nd and 3rd ramps.