Study on Calculation of the Buoyancy Drag Coefficient in the High-Speed Wind Tunnel Test

In order to obtain the drag coefficient in accuracy, it needs to correct the model's buoyancy drag coefficient in the high-speed wind tunnel test. However, there are several methods on calculating the buoyancy drag coefficient, each will generate a result differently. Three types of methods are studied in this paper, the formulas are derived, the buoyancy drag coefficients are calculated, and the results are compared in the end. It shows that the most exact method is the one based on pressure fitting function, it's suitable for correcting the model's drag coefficient with high accuracy requirement.