You need to make sure your measurements are actually representative of the flow regime you will actually have. You need to look at Reynolds number and mach numb

You need to make sure your measurements are actually representative of the flow regime you will actually have. You need to look at Reynolds number and mach number. If you use the actual model and don't use a small scale model, you just need to use the same flow speed as you will use in the application later. Then you could theoretically measure drag force and look at vortices to check where to modify the shape.