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Research Papers: Fluid-Structure Interaction

# A CFD Study of the Flow Field, Resultant Force, and Aerodynamic Torque on a Symmetric Disk Butterfly Valve in a Compressible Fluid

[+] Author and Article Information
Zachary Leutwyler

Kalsi Engineering Inc., Sugar Land, TX 77478zleutwyler@kalsi.com

Charles Dalton

Department of Mechanical Engineering, University of Houston, Houston, TX 77204-4006dalton@uh.edu

References 9-10 summarize the experimental work of Kalsi Engineering, Inc., which was documented in a proprietary report.

J. Pressure Vessel Technol 130(2), 021302 (Mar 19, 2008) (10 pages) doi:10.1115/1.2891929 History: Received November 27, 2006; Revised September 22, 2007; Published March 19, 2008

## Abstract

Butterfly valve performance coefficients are necessary for predicting the required torque necessary to operate the valve along with other essential parameters necessary for ensuring the safe operation. The availability of performance coefficients for compressible flow is limited, and experimental testing can be cost prohibitive. The capability of using computational fluid dynamics is a test to determine its viability for determining performance coefficients. The flow field, resultant force, and aerodynamic torque on a symmetric disk butterfly valve are studied computationally at disk positions $45deg$ and $70deg$ over a range of operating pressures. The range of pressure ratios was chosen to include subsonic and supersonic flow states. The flow fields were predicted using the $k$-epsilon renormalization group theory (RNG) turbulence model. The computational results were obtained using CFX 10 and were performed on an SGI ALTIX 330 . The flow field is illustrated using velocity contours colored by a Mach number, and the effects of the disk position and pressure ratio are illustrated using disk pressure profiles. The computational predictions for the aerodynamic torque coefficients are compared to test data at both $45deg$ and $70deg$. A simplistic model used to predict the resultant force acting on the disk is compared against the computational results to obtain a better understanding of the resultant force trend throughout the stroke. The numerical results were generally in good agreement with test data, although a few disparities existed.

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## Figures

Figure 1

A rotated view of the symmetric disk model

Figure 2

The test setup used by Kalsi (9-10) consisted of a test valve located at least 20-pipe diameters downstream of a header line that connected three large pressurized tanks. Testing consisted of full blowdown tests (with the downstream section removed) and partial blowdown tests (with the downstream section present and the downstream butterfly valve either 45deg or 90deg opened).

Figure 3

The surface model grid for the symmetric disk

Figure 4

The Mach number contours are shown for disk at 45deg at a VPR of 0.75. The flow is from left to right, and a rough wake region is visible downstream of the disk.

Figure 5

The pressure contours are shown for the (a) upstream face and (b) downstream face of the disk at 45deg for an VPR of 0.75. The disk is oriented so that the leading edge is up and the trailing edge is down.

Figure 6

The Mach number contours are shown for a disk at 45deg at a VPR of 0.22. The flow is from left to right, and the expansion of the gas downstream of the disk has suppressed the rough wake region present in the previous high-pressure ratio case.

Figure 7

The pressure contours are shown for the (a) upstream face and (b) downstream face of the disk at 45deg for a VPR of 0.22. The disk is oriented so that the leading edge is up and the trailing edge is down.

Figure 8

The velocity contours colored by the Mach number are shown for the 70deg disk position at a VPR of 0.96. The flow is from left to right and remains primarily unattached from the downstream face.

Figure 9

The pressure contours are shown for the (a) upstream face and (b) downstream face of the disk at 70deg for a VPR of 0.96. The disk is oriented so that the leading edge is up and the trailing edge is down.

Figure 10

The velocity contours colored by the Mach number are shown for the symmetric disk at 70deg for a VPR of 0.39. The flow is from left to right, and the rough wake is no longer present.

Figure 11

The pressure contours are shown for the (a) upstream face and (b) downstream face of the disk at 70deg for a VPR of 0.39. The disk is oriented so that the leading edge is up and the trailing edge is down.

Figure 12

The resultant force coefficient CR for the 45deg and 70deg disk position as a function of VPR

Figure 13

The maximum values of the numerical predictions for CL, CD, and CR are compared to values of the model predictions using Eqs. 6,7

Figure 14

The torque coefficient Ct for the symmetric disk at 45deg.

Figure 15

The torque coefficient Ct for the symmetric disk at 70deg. Bars are used to represent the fluctuation about the mean value.

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