Development of a Low-Density Wind Tunnel for Simulating Martian Atmospheric Flight

Abstract

A new type of wind tunnel that can simulate airfoil flow in the Mars atmosphere has been designed and constructed at Tohoku University. This wind tunnel is driven by ejector and designed to simulate low-density Martian atmosphere consisting of CO 2. The preliminary performance tests were conducted using air to investigate the operating envelop of the tunnel. It was demonstrated that this wind tunnel could cover the Reynolds number range from 10 4 to 10 5 and the Mach number range up to 0.71, allowing us to simulate low Reynolds number and high subsonic flow on Mars airplanes. Calibration tests were also conducted to investigate the flow characteristics in the test section. It was confirmed that the flow was kept uniform in the test section even when the total pressure was 1 kPa. There were significant effects of the boundary layer development on static pressure gradient along the test section. It was found that these effects of boundary layers could be corrected by inclining both the upper and lower walls of the test section. Nomenclature A Cross section area, m 2 P sup Supply pressure, MPa P t Total pressure, kPa R Gas constant of driving gas, J/kg-K T sup High pressure gas temperature, K W 1 Primary mass flow, kg/s W 2 Secondary mass flow, kg/s γ Specific heat ratio ρ Density, kg/m 3 ω Ratio of secondary mass flow to primary mass flow Subscripts L Upstream station of contraction section N Ejector nozzle throat S Downstream station of contraction section