Freestream velocity measurements and corrections for two-dimensional testing with splitter plates

In this study, the velocity correction method for two-dimensional wind tunnel testing is expanded for the case of testing airfoils between splitter plates. Despite the common use of splitter plates, the peculiar effects of this testing arrangement on the velocity correction are not well documented. The use of splitter plates in the test section has several advantages, but there are unfortunate consequences (such as spillage, entrainment and blockage to varying degrees) which require that the freestream velocity be measured directly between the splitter plates with the airfoil in the test section. In this case, the standard velocity correction for wall interference is not sufficient. An additional correction must be made to account for the change in velocity ahead of the airfoil model caused by the circulation about the airfoil. The results reveal that failing to correct for the circulation effect can yield significant errors in the aerodynamic coefficients. The proposed velocity correction provides results that are in agreement with other wind tunnel facilities and can be readily implemented in the data acquisition and reduction process.