General model derivation and verification of free-drop testing of aircraft in wind tunnel

Abstract

A variety of models of the wind tunnel test with different masses and inertias are needed when the Mach number and altitude of the object in flight change in the traditional light model method. This limits the characteristics of mass of the free-drop wind tunnel test model, increases the duration of such projects as well as their cost of processing, and renders the relevant tests inflexible to cause a significant waste of human and material resources. To solve these problems, this study improves the equation for the constraint on the mass in free-drop testing in the wind tunnel model by simplifying it. This is done according to the parameters of the separation conditions by using only one general test model and adjusting the separation velocity. We used the wing-pylon generic store for a computational fluid dynamics simulation. The results show little difference between the proposed and simplified testing method that uses a store test model, and the traditional method that uses a variety of test models. The difference between the general model design and the ideal wind tunnel test was less than 1.0% and 1.5% in terms of errors in the linear and angular displacements, respectively. The proposed method can thus ensure similarity between the results of the improved wind tunnel test and the store trajectory. It can shorten the test cycle while reducing the cost and increasing the flexibility of testing.