Experimental testing of the transverse horizontal axis water turbine

Abstract

This study outlines the procedures and results for a set of experiments on the transverse horizontal axis water turbine (THAWT), which is a variant of a Darrieus turbine. Testing of a 1/20th scale device was conducted in the combined wind, wave and current tank at Newcastle University. Flow depth and velocity were varied over a range of realistic Froude numbers for tidal streams. Various configurations of the device were tested to assess the merits of the THAWT design. Variants included a parallel-bladed device, a ‘truss’ device and a parallel-bladed device configured with blades pitched relative to the pitch circle tangent. Experiments were carried out using a speed controlled motor, allowing quasi-steady results to be taken over a range of tip speed ratios. The results demonstrate that, over a range of flow conditions, the device is capable of exceeding the Lanchester–Betz limit for kinetic efficiency. This is principally because of the relatively high blockage ratio that can be achieved with such a device.