Cycloidal Rotor Research Articles

Automatic differentiation for the optimization of a ship propulsion and steering system: a proof of concept

We describe the optimization of the Voith-Schneider-Propeller (VSP) which is an industrial propulsion and steering system of a ship combined in one module. The goal is to optimize efficiency of the VSP with respect to different design variables. In order to determine the efficiency, we have to use numerical simulations for the complex flow around the VSP. Such computations are performed with standard (partly commercial) flow solvers. For the numerical optimization, one would like to use gradient-based methods which requires derivatives of the flow variables with respect to the design parameters. In this paper, we investigate if Automatic Differentiation (AD) offers a method to compute the required derivatives in the described framework. As a proof of concept, we realize AD for the 2D-code Caffa and the 3D-code Comet, for the simplified model of optimizing efficiency with respect to the angle of attack of one single blade (like an airfoil). We show that AD gives smooth derivatives, whereas finite differences show oscillations. This regularization effect is even more pronounced in the 3D-case. Numerical optimization by AD and Newton's method shows almost optimal convergence rates.

Performance of a Cycloidal Rotor Concept for Micro Air Vehicle Applications

Performance of a Cycloidal Rotor Concept for Micro Air Vehicle Applications

Aerodynamic performance enhancement of cycloidal rotor according to blade pivot point movement and preset angle adjustment

This paper describes aerodynamic performance enhancement of cycloidal rotor according to the blade pivot point movement and the blade preset angle adjustment. Cycloidal blade system which consists of several blades rotating about an axis in parallel direction and changing its pitch angle periodically, is a propulsion mechanism of a new concept vertical take off and landing aircraft, cyclocopter. Based on the designed geometry of cyclocopter, numerical analysis was carried out by a general purpose commercial CFD program, STAR-CD. According to tills analysis, the efficiency of cycloidal rotor could be improved more than 15% by the introduced methods.

Comments on “Simple explicit formulae for calculating limit dimensions to avoid undercutting in the rotor of a Cycloid rotor pump” by Ye, Zhonghe; Zhang, Wei; Huang, Qinghai; Chen, Chuanming [Mech. Mach. Theory 41 (4) (2006) 405–414

Comments on “Simple explicit formulae for calculating limit dimensions to avoid undercutting in the rotor of a Cycloid rotor pump” by Ye, Zhonghe; Zhang, Wei; Huang, Qinghai; Chen, Chuanming [Mech. Mach. Theory 41 (4) (2006) 405–414

Numerical optimization of the Voith‐Schneider® Propeller

AbstractThe Voith‐Schneider® Propeller (VSP) is an efficient ship propeller that was invented by Ernst Leo Schneider (1894–1975) in 1927. It is a complex propeller having several parameters determining the behavior of the VSP. One of them is the Blade Steering Curve (BSC) which describes the angle of a propeller blade for a time instant. We investigate the choice of this BSC in order to optimize the efficiency of the VSP. We use numerical optimization and Computational Fluid Dynamics (CFD), in particular the Vortex‐Lattice Method for the optimization and Finite Volume Method for validation. We obtain a significant improvement of 4.8%.

Simple explicit formulae for calculating limit dimensions to avoid undercutting in the rotor of a Cycloid rotor pump

A new and simple method is used to derive the formulae for the tooth profile of the small rotor in a Cycloid rotor pump. Undercutting is avoided by calculating the maximum radius of curvature of the small rotor tooth profile on the convex section. It is found that undercutting can be avoided so long as the maximum value is not larger than zero. The derivation of the formula for the radius of curvature is based not on the tooth profile formulae of the small rotor, but on those of the locus of the centre of the circular tooth of the large rotor relative to a coordinate system fixed to the small rotor. This simplified method yields explicit formulae for calculating limit dimensions of the large rotor to avoid undercutting on the tooth profile of the small rotor.

On the Efficiency of a Class of Nonstationary Ship Propellers

Nonstationary ship propellers belonging to a certain class which includes, among others, the Voith-Schneider propeller, are considered. The free vorticity left behind by an optimum propeller is characterized. The theory is three dimensional, hence tip effects are included.