Feasibility of airfoil tests with a small high subsonic cryogenic wind tunnel

Abstract

A cryogenic wind tunnel has a capability to perform relatively high Reynolds number airfoil testing using a small airfoil model. However, it is desirable to use a model as large as possible to utilize the high Reynolds number flow capability of the cryogenic wind tunnel. The most serious problem on the airfoil testing is the tunnel sidewall interference. As the NDA cryogenic tunnel has a very narrow width, and the possible shortest chord length of model is 0.06 m with our present fabricating method, the aspect ratio of models for the present tunnel is only up to 1.0. The Barnwell-Sewall and the Murthy methods are the readily available corrections, and were applied to the experimental pressure distributions of airfoils which have aspect ratios less than unity in order to evaluate feasibility of airfoil tests with models of such low aspect ratios, and to contribute to the database on the wind tunnel testing techniques. From the experimental study, the simple global correction to the main stream conditions still works in some degree for the experimental data of low aspect ratio cases. This result may support the feasibility of airfoil tests with models of low aspect ratios as first order tests.