Study and verification on similarity theory for propellers of stratospheric airships

According to similarity theory of propellers, equal Reynolds number and equal advanced ratio similarity was selected as a group of similarity criterion combination. The effect of different density on the propeller similarity criterion was investigated by using numerical simulation. The chosen similarity criterion and correctness of applicability were verified. The relevant test results obtained by using the ground wind tunnel test on the scaled propeller model and the numerical simulation results of the stratosphere propellers were compared and analyzed. The results show that the nondimensional aerodynamic character curves of propellers at different altitudes are nearly agreement with each other. And the experimental results in ground wind tunnel is corresponding to the results of numerical simulations. It means that the air density influences little of propeller similarity parameters. So that, the scaled model experiment of propeller for stratospheric airships in ground wind tunnel is feasible according to equal Reynolds number and advanced ratio similarity, and provides reference basis for the wind tunnel test of propellers in stratosphere.