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Documentation

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:

  • Pressure drop
  • Torque

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:

butterfly valve at 20 degrees inside pipe
Figure 1: Pipe model with butterfly valve inside opening at 20° angle

The dimensions of the pipe can be seen in the table below:

DimensionValue \([m]\)
Upstream length14.4
Downstream length27
Valve & pipe diameter (D)1.8
Valve maximum thickness0.36
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 mesher and the following table lists the details of the mesh:

Mesh TypeNumber of cellsType
Standard6.4 Million3D Tetrahedral/Hexahedral
Table 2: Mesh data for butterfly valve validation case
fine mesh for flow domain 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.

refined mesh of butterfly valve performed using simscale standard algorithm
Figure 3: Standard meshing performed on valve with refinements at hinges

Simulation Setup

Fluid:

  • Water
    • Kinematic viscosity \((\nu)\): 9.338e-7 \(m^2/s\)
    • Density \((\rho)\): 997.3 \(kg/m^3\)

Boundary Conditions:

boundary condition overview
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 ConditionValue
Velocity inlet3 \(m/s\)
Pressure outlet0 \(Pa\)
No-slip wallPipe 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:

flow coefficient comparison
Figure 5: Flow coefficient comparison between reference results and SimScale
torque coefficient comparison
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:

cutting plane of velocity distribution when the valve is opened at a 20° - 50° angle
Figure 7: Velocity magnitude contours inside the pipe at the centerline when the valve is opened at a 20° – 50° angle.
cutting plane of velocity distribution when the valve is opened at a 60° - 85° angle
Figure 8: Velocity magnitude contours inside the pipe at the centerline when the valve is opened at a 60° – 85° angle.

Note

If you still encounter problems validating you simulation, then please post the issue on our forum or contact us.

Last updated: May 19th, 2021

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