Wall Interference during Testing a Blunt Body in a Transonic Flow

This paper presents the results of numerical simulation of a transonic flow around a blunt body at a zero angle of attack in a test section with porous walls of the T-128 wind tunnel (WT) (Russia, Central Aerohydrodynamic Institute (TsAGI)). The calculations are performed using the EWT-128 TsAGI software package, which uses Darcy-type boundary conditions on the walls of the test section, whose porosity coefficient depends on the direction of the gas flow through the perforated surface. A comparison is made of the calculated and experimental drag coefficients of the model, as well as distributions of the isentropic Mach number on the model and on the perforated walls of the test section of the WT. A method is proposed for determining the correction to the Mach number of the oncoming flow to eliminate the wall interference of the test section in an aerodynamic experiment. The drag coefficients obtained as a result of calculations under WT conditions are corrected for the influence of the flow boundaries and compared with the free flow data. The calculated corrections are used to correct the experimental data.