J. Martinez Schramm

Force and Moment Measurements on a Free-Flying Capsule in a Shock Tunnel

Experiments to measure the forces and moments acting on a blunted-cone capsule model are conducted in the High Enthalpy Shock Tunnel Gottingen. A free-flying arrangement is employed, whereby the mo...

Combustion Experiments Performed within the LAPCAT I Project - An Overview

The European Commission co-funded research project LAPCAT I - Long-Term Advanced Propulsion Concepts and Technologies - was performed within the timeframe spring 2005 until spring 2008. The project was coordinated by the European Space Research and Technology Center, ESA-ESTEC and the consortium consisted of 11 partners from industry, research institutions and universities. The objectives of LAPCAT I were to identify and assess critical propulsion technologies required to reduce long-distance flights, e.g. from Brussels to Sydney, to less than 4 hours. Achieving this goal intrinsically requires a new flight regime for commercial transport with Mach numbers ranging from 4 to 8. At these high speeds, classical turbo-jet engines are not feasible and need to be replaced by advanced airbreathing engines. Different combined cycles, i.e. turbine based combined cycles (TBCC) and rocket based combined cycles (RBCC) were evaluated both on fundamental research level and in the framework of vehicle system studies. The research activities of the project were structured in six main technical work packages. In the present paper, a synthesis of the work package related to combustion experiments is given. The research focused on supersonic combustion experiments in a connected tube facility, investigations of a generic supersonic combustion configuration consisting of intake, combustor and exhaust in a free jet facility, shock tube studies of the disintegration process of hydro carbons in high pressure combustion and the investigation of high pressure combustion of liquid oxygen / hydro carbons in a micro combustor.

Experimental and numerical investigation of high enthalpy flow past a cylinder in HEG

Basic aerodynamic configurations are well suited to study fundamental aspects of high enthalpy flows. A test campaign of the flow around a cylinder has been performed in the High Enthalpy Shock Tunnel Gottingen HEG. Measurements of density distributions in the shock layer as well as surface pressure and heat flux were taken. The flow in the shock layer is subjected to various relaxation phenomena and therefore, the presented measurements provide a useful basis for the validation of physico-chemical models used in CFD codes. This paper presents results of the test campaign and comparisons of measurements to numerical computations. The sensitivity of the CFD results to different parameters of physico-chemical models will be discussed.

High Enthalpy Non-Equilibrium Shock Layer Flows: Selected Practical Applications

A space vehicle (re)-entering the atmosphere of Earth or a different planet is subjected to flows that place the vehicle under extreme physical conditions. High temperature effects such as dissociation, vibrational excitation, electronic excitation or gas radiation within the shock layer in front of the vehicle will have to be correctly modelled by computational fluid dynamics (CFD) tools to be used in the framework of the design process of future entry or re-entry configurations. One important step during the development of a CFD code is the validation of the physical-chemical models used to describe the high temperature effects. The strategy generally pursued is to validate these models with data obtained in ground based testing facilities and / or flight tests. The validated CFD tool can subsequently be used for ground-to-flight extrapolation and for the computation of the flow field past (re)-entry vehicles at free flight conditions.

Time resolved holographic interferometry for short duration hypersonic high enthalpy test facilities

The High Enthalpy Shock Tunnel Gottingen (HEG) of the German Aerospace Cen- ter (DLR) is one of the major European hypersonic test facilities. The HEG can operate over a wide range of test conditions, from low altitude high density Mach 6 flows through the simulation of Mach 8 flow at approximately 30 km altitude up to high enthalpy re-entry conditions. Full utilization of such ground based high enthalpy impulse facilities, with typical test times in the order of one to several milliseconds, requires detailed knowledge of the flow in the test section, and its starting processes. Further, the temporal development of the model flow must be known in order to assure that a steady flow has developed during the test time. For that reason a high speed flow visualization (HSFV) system has been implemented at HEG using the schlieren and shadowgraph technique. This paper describes a feasibility study undertaken to extend the optical measurement capabilities of the HEG by combining the HSFV system with the phase step holographic interferometry (HI) system used so far in single shot mode.