Performance Investigation of the Immersed Depth Effects on a Water Wheel Using Experimental and Numerical Analyses

Mengshang Zhao,Yuan Zheng,Qinghong Tang,Yuquan Zhang,Chunxia Yang

doi:10.3390/w12040982

Abstract

The purpose of this research is to study the effect of different immersed depths on water wheel performance and flow characteristics using numerical simulations. The results indicate that the simulation methods are consistent with experiments with a maximum error less than 5%. Under the same rotational speeds, the efficiency is much higher and the fluctuation amplitude of the torque is much smaller as the immersed radius ratio increases, and until an immersed radius ratio of 82.76%, the wheel shows the best performance, achieving a maximum efficiency of 18.05% at a tip-speed ratio (TSR) of 0.1984. The average difference in water level increases as the immersed radius ratio increases until 82.76%. The water area is much wider and the water volume fraction shows more intense change at the inlet stage at a deep immersed depth. At an immersed radius ratio of 82.76%, some air intrudes into the water at the inlet stage, coupled with a dramatic change in the water volume fraction that would make the flow more complex. Furthermore, eddies are found to gradually generate in a single flow channel nearly at the same time, except for an immersed depth of 1.2 m. However, eddies generate in two flow channels and can develop initial vortexes earlier than other cases because of the elevation of the upstream water level at an immersed radius ratio of 82.76%.

Highlights

Renewable energy gradually attracts people’s attention owing to the fact that there are huge demands for energy and an over reliance on conventional fossil fuels [1]
At the immersed radius ratio of 68.96% (1.0 m), the X is varied near 1 at different rotational speeds; this immersed radius ratio can be considered a transition from stream water wheel to RHPM, and here the power coefficient Cp is used at this immersed radius ratio
Performance and flow characteristics for a real-size water wheel applied in an open channel, and Combinedobjective with the of

Summary

Introduction

Renewable energy gradually attracts people’s attention owing to the fact that there are huge demands for energy and an over reliance on conventional fossil fuels [1]. Hydropower resources are valued by all over the world for its clean, renewable and abundant characteristics [2,3]. Hydraulic constructions are needed, such as pressured conduits, dams, reservoirs and so on [4,5]. They always need much time and huge investments. Low and ultra-low head-generating devices are increasingly popular as a number of large scale and capacity hydropower stations have been constructed [6,7]; it would be an effective way to use a water wheel to generate electricity in low and ultra-low head resources, such as open channels, streams and so on

Objectives

Results

Conclusion