The arc-heated LBK wind tunnel with its two L2K (1 MW) and L3K (6 MW) test sections is one of the key facilities for the characterisation of heat shield materials and qualification of hot structures and high temperature sensors of spacecraft in Europe.
The L2K can be operated with different types of gas and therefore enables the simulation of different atmospheres. Apart from the Earth’s atmosphere the atmosphere of Mars, which consists of carbon dioxide is of major significance for current space projects. In the L2K, dust particles can also be added to the flow. This is important for the entry into the atomosphere of Mars, as large quantities of dust particles can be whirled up into high atmospheric layers.
In the L2K test section, stagnation point models with a diameter of up to 100 mm can be tested at cold wall heat flux to 2 MW/m2 and Pitot pressures up to 160 hPa. The model size in the plate configuration is 220 mm (long) x 140 mm (wide) and 50 mm (high). The working gas in the L2K is heated with a highly robust Huels type arc heater, which enables test duration of up to 120 minutes.
Apart from pure characterisation and qualification tests, L2K also enables the use of sophisticated spectroscopic measuring methods such as LIF (Laser Induced Fluorescence) and infrared thermography (IR), which supply valuable data for the validation of numerical methods for the calculation of high enthalpy flows.
This facility has been upgraded in recent years to cover entry problems in the atmospheres of other planets such as Mars. Due to the flight relevant simulation of the particle-loaded flow in the atmosphere of Mars and its successful characterisation with modern measuring methods, the L2K plays a key role for these tasks in Europe.