Experimental Study of ExoMars Sub- and Transonic Aerodynamics and Heat Shield Separation in HST

Abstract

In the framework of the ESA ExoMars project an experimental investigation has been conducted in the transonic DNW wind tunnel HST with two emphases. First the static aerodynamic behaviour of the complete descent module has been investigated in the sub- to transonic flow regime, duplicating reference flight trajectory conditions through the Martian atmosphere. Therefore force and moment coefficients have been derived by means of a six component internal balance with additional pressure signals to enable base pressure corrections. The second main objective was the aerodynamic characterization of the staging process between the capsule’s heat shield and its back cover at corresponding trajectory flight conditions. For this attempt models were available for the capsule’s single parts after separation, e.g. heat shield and back cover. These components have been investigated individually to characterize its behaviour after completion of the separation process as well as to gain reference data to compare to the behaviour during the actual staging process. This flight phase has been simulated in detail by thoroughly modifying the orientation of the separating models to each other. This was enabled by a modular distance between the separating components and modification of the angle of attack. Beside force and moment measurements on the heat shield, the back cover has been equipped with 12 static as well as 12 dynamic pressure sensors. This paper gives an overview of selected results gathered during this test campaign. The measured coefficients for the complete descent module as well as for the separating models are analyzed comparing typical capsule configuration behaviour. Depending on the distance between the separating models clear interferences are evident in both force and pressure signals.