The Design and Development of a Recirculating Water Channel: A Critical Assessment

Millward, Adrian (2001). The Design and Development of a Recirculating Water Channel: A Critical Assessment. MPhil thesis The Open University.

DOI: https://doi.org/10.21954/ou.ro.0000fbbe

Abstract

The thesis critically assesses the design, development and equipment of a recirculating water channel: the channel in the Department of Engineering at the University of Liverpool It is intended to provide a valuable reference manual for such facilities.

The channel is a versatile item of equipment wliich can be used in four different configurations:- as a free surface water channel, including the ability to simulate shallow water and also to generate regular head waves; as a water tunnel; as a free surface cavitation channel or as a cavitation tunnel, with a minimum pressure of 1/30 atmosphere. Uie working section is 3.66m long, 1.4m wide and 0.84m deep with a maximum water speed of 5.7 m/s.

The thesis includes:

1. A description of the water channel in its four configurations and earlier development of a jet injection system to overcome a velocity defect at the water surface.

The flow velocity in tlie working section and methods of flow measurement are discussed together with new measurements of turbulence velocity and the time to reach equilibrium speed.

The wavemaker has been shown to produce waves which are good approximations to a sinusoidal shape at low water speeds and can be maintained over a long period of time. At higher speeds it was found that the wave shape progressively degenerated; methods for improving the wave-maker are suggested.

2. The force measuring equipment is reviewed including a dynamometer for ship models and a miniature version for much smaller forces obtained on sea shells at low water speeds.

3. The principles of model testing are discussed together with a technique for measuring the actual wetted surface area in the case of fast ships. A new experimental and theoretical investigation into the effect of model size relative to the size of the working section is reported.

4. A final chapter reviews the design of the flume and all its equipment. Suggestions are made for further improvements suitable for a future water channel.