A Study of High Speed Gas Flow by Hydraulic Analogy : The 4th Report, Flow Around an Airfoil

Abstract

When the high speed aerodynamic characteristics of airfoils were investigated by the experimental method using a shallow water flow with free surface, the author showed that four dimensionless numbers must be equal for the flows around two airfoils in order that the variations of water depth around two geometrically similar airfoils might become similar to each other. However, as it is difficult to make these four dimensionless numbers equal for the two systems at the same time, the quantitative experimental results necessitate a certain defined magnitude of airfoil and water depth. On the other hand, the experimental results of the defined magnitude of an airfoil by the water flow of defined depth with free surface are different from the wind tunnel experimental results of the airfoil, because both Reynolds numbers differ from each other considerably. Therefore, comparing both experimental results, the experimental formulae of correction were found. Moreover, the photographs of flow pattern around airfoils were taken, to make the conditions of flow clear to a certain extent.