Hydraulic Yaw System for Wind Turbines with New Compact Hydraulic Motor Principle

摘要

This paper presents a new hydraulic yaw system for wind turbines. The basic component is a new type of hydraulic motor characterized by an extraordinary high specific displacement yielding high output torque in a compact form. The focus in the paper is the volumetric efficiency of the motor, which is based on leakage flow. The most critical gaps in the motor, across the end faces of the rotor, are investigated both by a fluid structural interaction simulation model and by experimental prototype tests. The simulation model is the basis for the motor design and the manufacturing tolerances. The volumetric efficiency is highly dependent on the structural deflections caused by the pressure distribution in the fluid films across the rotor. This gap height is measured with a 0.1μm resolution "SMAC Moving Coil Actuator" in the experimental test setup. When the pressure in the pressure compensation volumes is minimizing the deflections, the measured gap height is around h = 10μm and the volumetric efficiency of the motor is around η_v = 0.85. By decreasing the initial gaps from the manufacturing process, this volumetric efficiency can be further increased.