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Abstract

This thesis presents a model for conical entrance orifice plate flow sensor and the results of the applica-tion of the model.

The model for the conical entrance orifice plate flow sensor was developed using a low Reynolds number k-e model of turbulence - the Lam and Bremhorst k-e model, and the 'PHOENICS' computer code. The flow fields modelled were axisymmetric and the geometry of the conical entrance orifice plate is in accordance with that given in BS 1042 : Section 1.2.

A pipe 100 mm in diameter and with water as the working fluid was used in the simulation. Numerical results were obtained with diameter ratios ¡3 equal to 0.1, 0.2 and 0.3, and for pipe Reynolds numbers between 80 and 60,000. The model predicted the discharge coeffi-cient to within ± 3 % of the value stated in the British Standard for the range of f3 ratios and Reynolds numbers investigated, which suggest that the conical entrance orifice plate can be used at Reynolds numbers higher than that specified in BS 1042 : Section 1.2 : 1989 for the smaller /3 ratios.

The model also suggested that the discharge coefficient is a function of ¡3; that pressure tappings other than corner tappings can be used and the conical entrance orifice was relatively insensitive to turbulence level upstream at the pipe inlet. The effects of geomet-ric tolerances were explored and the results indicated that some latitude on the geometric tolerances as specified in the Standard may be allowed.

Publication Type:	Thesis (Doctoral)
Subjects:	T Technology > TJ Mechanical engineering and machinery T Technology > TK Electrical engineering. Electronics Nuclear engineering
Departments:	School of Science & Technology > School of Science & Technology Doctoral Theses Doctoral Theses School of Science & Technology > Engineering

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