Gas Dynamics

  Graphical Abstract of the Reasearch Area Copyright: © HGD  

The field of gas dynamics of the HGD is engaged in numerical and experimental investigations of compressible i.e. density-changing flows.

For this purpose, a repertoire of different test facilities is available at the HGD. These test facilities generate flow under transonic, supersonic and hypersonic conditions. The test facilities are mostly shock or detonation tubes and generate extreme flow conditions (high Mach number, high enthalpy) for a short period of time 4-10 ms. For the generation of transsonic flow, it exists a facility that can be operate as a shock tube as well as a ludwieg tube. In the Ludwieg tube operation mode, the testing time of the facility can be extended from 4 ms, which is typical for shock tubes, up to 170 ms. Due to the high flow quality and the optical access, the Ludwieg tube (LTK) is particularly suitable for airfoil or aerodynamic investigations at transonic speed.

Flow conditions, such as those that occur when a spacecraft re-enters the Earth's atmosphere, can be simulated with the hypersonic shock wave channel (TH2). This facility generates hypersonic flow with Mach numbers from 6 to 12 and a static temperature of the free stream flow up to 1300 K.

The test section is located in a large and walk-in vessel with optical access, so that even relatively large models can be investigated visually with schlieren and infrared technology as well as with pressure, thermal and force measurement technology. The research area of the HGD extends not only to compressible flow investigations, but also to forming processes and to the coating of materials by shock or detonation waves. The HDG has a selection of high-quality optical components for flow visualization using the shadow, schlieren and interferometry technique. For the latter, one of the last functional Mach-Zehnder interferometers is available at the HGD.

The HGD is specialized in short-term measurement technology in the field of pressure, force and temperature measurement. For temperature measurements, thermocouples, which are in house designed, are used. These thermocouples have been tested and further developed over the years in the HGD.