The H2K is a „Blow-Down“ wind tunnel with a free jet test section. It uses contoured, axially symmetrical and replaceable nozzles. For aerodynamic testing nozzles for Mach numbers of 4.8, 5.3, 6.0, 7.0, 8.7 and 11.2 are available. For aerothermal tests on probes smaller nozzles with Mach numbers of 3.0 and 5.0 are also in use.
In order to achieve the pressure ratio required for the build-up of the nozzle flow for approx. 30 seconds, the pressure in the test chamber is reduced by a vacuum sphere. Due to the large expansion of the air in the nozzle, its static temperature decreases significantly. To prevent condensation of air particles and for tests at high temperatures, the air is preheated. Eight electric heaters with a maximum electrical power of 5 MW heat the air up to 1100 K. Depending on the test set-up, between 8 and 10 tests per day can be carried out.