Validation Case: Butterfly Valve This validation case belongs to fluid dynamics and the aim of this case is to validate the following parameters inside a pipe with a butterfly valve:
The simulation results of SimScale were compared to the results presented in the study done by Song, Xue Guan and Park, Young Chui with the title “Numerical Analysis of Butterfly Valve – Prediction of Flow Coefficient and Hydrodynamic Torque Coefficient “\(^1\).
Geometry The model used in this validation case is a pipe with a discus shaped butterfly valve inside, which can be seen below:
Figure 1: Pipe model with butterfly valve inside opening at 20° angle The dimensions of the pipe can be seen in the table below:
Dimension Value \([m]\) Upstream length 14.4 Downstream length 27 Valve & pipe diameter (D) 1.8 Valve maximum thickness 0.36
Table 1: Pipe and valve dimension 9 variants of valve opening angles ranging from 20° to 85° were used as a comparison to the reference study.
Analysis Type and Mesh Tool Type : OpenFOAM®
Analysis Type : Steady state, Incompressible with K-Omega SST turbulence model
Mesh and Element Types :
The mesh was created with SimScale’s Standard
Mesh Type Number of cells Type Standard 6.4 Million 3D Tetrahedral/Hexahedral
Table 2: Mesh data for butterfly valve validation case Figure 2: Mesh of flow domain with fineness level 7 Furthermore, region refinements were also added in the area near the hinges of the valve so the calculation in those areas can be done accurately.
Figure 3: Standard meshing performed on valve with refinements at hinges Simulation Setup Fluid :
WaterKinematic viscosity \((\nu)\): 9.338e-7 \(m^2/s\) Density \((\rho)\): 997.3 \(kg/m^3\) Boundary Conditions :
Figure 4: Boundary condition overview where flow goes from left to right The boundary conditions are the same for all opening angles and were assigned as shown in Table 3:
Boundary Condition Value Velocity inlet 3 \(m/s\) Pressure outlet 0 \(Pa\) No-slip wall Pipe walls and valve surface
Table 3: Boundary conditions for pipe and valve Reference Solution The reference solution for the flow coefficient and the torque coefficient is given in the following formulae:
Flow coefficient :
$$c_v = \frac{Q}{\sqrt{\Delta P \times S_g}} \tag{1}$$
where:
\(c_v\): flow coefficient \(Q\): flow discharge \((GPM-Gallons\,per\,minute)\) \(\Delta P\): pressure drop \((psi)\) \(S_g\): specific gravity of water Torque coefficient :
$$c_t = \frac{T(x)}{\Delta P \times d^3} \tag{2}$$
where:
\(c_t\): torque coefficient \(T(x)\): torque in the x-axis \((N.m)\) \(\Delta P\): pressure drop \((psi)\) \(d\): diameter of pipe \((in)\) Result Comparison Comparison of the flow and torque coefficients obtained from SimScale against the reference results obtained from [1] is given below:
Figure 5: Flow coefficient comparison between reference results and SimScale Figure 6: Torque coefficient comparison between reference results and SimScale The flow contours inside the pipe when the valve is opened at the simulated opening angles as observed in our online post-processor:
Figure 7: Velocity magnitude contours inside the pipe at the centerline when the valve is opened at a 20° – 50° angle. Figure 8: Velocity magnitude contours inside the pipe at the centerline when the valve is opened at a 60° – 85° angle. If you still encounter problems validating you simulation, then please post the issue on our forum or contact us .
Last updated: October 23rd, 2020
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