Design Analysis and Cost Optimisation of a Multi-Hole Trim Using CFD in Control Valves

  • Ngqabutho Sibanda

Student thesis: Doctoral Thesis


An experimental and numerical study has been performed on a 4-inch globe control valve with the objective of diagnosing local flow behavior and quantifying the different flow parameters to the total valve performance. A computer-based data acquisition system, coupled with pressure transducers, were used to obtain experimental measurements of both the upstream and downstream pressures to calculate pressure drop across the valve. The acquired data was used to validate the results of numerical simulations. Four models of single stage multi-hole trims with different hole sizes were numerically studied. The pressure-drop and hence flow coefficient (Cv) of individual holes were quantified. Flow coefficient (Cv) is defined as defined as the volume of water in gallons per minute (GPM) at 60°F that will flow through a fully open valve with a pressure differential of 1 psi across the valve. The flow behavior around the trim was obtained, and these provided valuable insight into the mechanisms that determine the performance of a multi-hole trim. These were used to establish the relationship between the flow coefficient of the valve with passageways in the cage.
The focus of the study was directed towards the development and optimization of a single stage multi-hole trim for a globe control valve. Relationships between parameters such as trim hole diameter, hole height (row position) and hole angular position were examined extensively. The results were used to develop a series of analytical expressions to represent the effect of each geometrical feature and predict local Cv. It is envisaged that proposed expressions will feed into current design methodologies for control valve multi-hole trims which offers the prospect of improved overall performance.
The final part of the study was to optimise the control valve through a least cost method where the valve selection is based on total cost as a function of valve diameter. A case study example is discussed to show the control valve life cycle cost which has been incorporated in the optimised design.
Date of Award11 Nov 2022
Original languageEnglish
SupervisorRakesh Mishra (Main Supervisor)

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