A study of jet flow and reattachment in control valves

Begg, R. D (1965) A study of jet flow and reattachment in control valves. PhD thesis, University of Glasgow.

Abstract

The work continues investigations into the characteristics of piston control valves; in particular it examines fluid flow through constrictions similar to the valve port. The various flow phenomena associated with piston valves are reviewed, then a closer study is made of reports examining more specific aspects of the flow including separation, jet flow reattachment and turbulent entrainment. From these reports a mathematical model of the entrainment process inside valves is constructed for incompressible flow, and predictions of reattachment bubble lengths obtained for various port geometries. Experimental results obtained using a two-dimensional model of the valve port show that the measured bubble lengths hear the same relationship to the predictions as is found in two other investigations of reattaching jet flow in similar configurations which are analysed on the same basis. A further study of reports on compressible jet flow yields three methods to predict the jet angle of compressible flow through the valve geometry, and one is used to obtain theoretical values of jet angle and thickness over a range of geometries and pressure ratios. Further experimental results, obtained from the same valve model, verify the predictions of jet angle and establish the characteristics of the compressible bubble throughout a wide range of pressure ratios and orifice dimensions During the tests several distinct patterns of supersonic flow were observed using a schlieren light system and recorded by photographing theme Prom consideration of the measurements and theoretical predictions some explanation is offered for the observed bubble behaviour and the various flow patterns. Finally the effect of these characteristics on the performance of piston valves is discussed and an attempt made' to describe previously reported valve behaviour in terms of the measured bubble flow patterns.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Adviser: G DS Maclellan
• Keywords: Mechanical engineering, Fluid mechanics, Hydraulic engineering
• Date of Award: 1965
• Depositing User: Enlighten Team
• Unique ID: glathesis:1965-72369
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 24 May 2019 15:12
• Last Modified: 24 May 2019 15:12
• URI: https://theses.gla.ac.uk/id/eprint/72369