Abstract: A wind tunnel having a plurality of walls surrounding a test section. The walls are provided with a plurality of longitudinal slots. A channel is formed behind each slot. Each channel contains a flexible channel bottom. The shape of the flexible channel bottom may be modified by adjustment devices. The influence of the walls on air flow is thereby decreased and made easier to compute. The influence of the walls on the testing of models is reduced, wind tunnel simulation is improved, and a more accurate and reliable computation of residual influences is provided.

Abstract: For cooling down a cryogenic model, provided for testing in a cryogenic wind tunnel, to the wind tunnel temperature and for performing mounting work and configurational changes on the cryogenic model, there is provided a working chamber which is supplied with warm air so that working personnel can enter it. The working chamber contains an insulating box, made from heat-insulating material, which has an open top and into which cold air is injected. The insulating box accommodates the cryogenic model under cold air conditions. Persons can perform manipulations on the cryogenic model while leaning over the edge of the insulating box. The cryogenic model is held on a holder which can be lifted upwardly out of the insulating box. Removal of the cryogenic model from the working chamber is possible by opening a top door.