A Procedure for Propeller Design by Inverse （螺旋桨设计的逆过程）.pdfVIP

A Procedure for Propeller Design by Inverse Methods by Richard Eppler and Martin Hepperle Institut A für Mechanik Universität Stuttgart Pfaffenwaldring 9 D-7000 Stuttgart 80 FRG Summary Two different inverse methods are applied to the design of new propellers. The first one is based on a theory of Prandtl and Betz [1], which was revived and successfully applied by Larrabee [3]. This method starts from the optimal circulation distribution for the Propeller blade and gives simple relationships between chord and angle of attack for the optimal propeller under design conditions. The off-design cases are treated by Larrabee using a simple approximate theory. This is a good approximation as long as the off-design cases are not too far from the optimum case. This Propeller theory yields for each radial station of the blade, the lift coefficients for the design case and for the different off-design cases. Once the Propeller theory has delivered the requirements for the Propeller airfoils, the second inverse theory is applied. It computes the propeller profiles from the given velocity distributions. This theory was first published in 1957 and later combined with boundary layer computation methods [4]. This method was recently extended to subsonic compressible flow, using a method of Labrujere et al. [5]. It allows in a very simple way to consider compressibility effects as long as no locally supersonic regions are present. It turns out that the requirements near the blade tip are exclusively determined by compressibility effects, while towards the hub the velocity specifications must consider the necessary profile thickness and viscous effects. Details and examples including the improvements which were achieved are described. 1. Propeller Design It was shown in 1919 by A. Betz [l] that the induced loss of a propeller is minimized if the propeller slipstream has a constant axial velocity and if each