Steady State Simulation on a Flow over a Throttle Body
Objective:
In this challenge, we are going to perform a flow over a throttle body on a steady state condition.
Procedure:
Flow over a throttle body analysis very helpful to learn the mass flow rate and the loss when the throttle is open and closed. However this effect can be captured in the transient. Here we are using steady state simulation to capture the flow over the throttle body and view the stream line how the flow is happened.
Procedure:
Geometry:
The above figure is the outer geometry. It is a hollow pipe , where the flow is happened inside the tube. There is a throttle placed inside the body. Here i am making as inlet from the top and water is coming out(outlet) in positive x direction.Here we using throttle is opened fully and analysis the flow on the throttle body.
Once the geometry is imported it is better to run the diagnosis to see whether the geometry have error or not.
Inside , we see that the throttle is placed and here we are running the analysis as 2d so there is no need for the thickness, if we are interesting to calculate the heat treatment or CHT it is necessary to define the thickness.
Once we remove the thickness and run the analysis we see that there is a open edge error shown when we run the diagnosis.
To remove the open edge, use the patch option to fill the open edge and consider that faces as outlet and the inlet.
After do the modification, it is must to check the normal. Here we have two body. One body is the pipe, outer part, their normal must be inward(towards the faces) because the flow happened inside the body and for the throttle body the normal shows away from the throttle body, because the flow happened over the throttle body.
If not, then using the transform normal to change the normal direction.
Above figure shows the normal how it is placed for the simulation.
In converge studio, ideal unit is metre. By using the option to enable the bounding box for the geometry it shows the dimension of the geometry . Here it show 106m and it is not much efficient to solve for the ideal PC, so we scaled the value of x y and z into the conversion of 0.001.
Now it shows the value of dimension in 0.2 for x axis similarly it shown for the both y and z axis.
Case SetUp:
After fixing the geometry, go to the case setup tab to set the value for the analysis.
Here we are using the pressure based steady state solver and considered predefined material as air.
The above figure shows the run parameter that we are using for this simulation.
Here the above figure shows the boundary flagging. Here for the inlet, use the inflow similarly outlet use the outflow. Based upon the initial condition we give neuman or dirichlet boundary condition. throttle kept as stationary.
Define the region and apply the region to the boundary. For the mesh grid we are using the base grid mesh.
When we give the base grid and run as no hydrodynamic and view the mesh, there is very less element around the throttle. To capture the effect more precisely, we need more number of mesh. But increase the element increases the solver time. So we can use the embedding option to create more element only around the throttle body to capture the effect.
Export the inpu file and use the cygwin to read the file and write the output file. By using the post processor in converge we convert the output file to the usable output file in paraview.
Post Processing:
The above geometry shown in the paraview.
By using line plotting model we can analysis result for the different function.
The above figure shows the mass flow rate. From the plot it is shows inlet and outlet and loss is happened due to the bend of the pipe and the throttle body present.
The above figure shows the static and total pressure, Pressure obtained at the static condition is the static pressure, total pressure is the addition of static pressure and dynamic pressure. At the inlet static pressure is vary and the outlet static pressure is constant. But the total pressure at the inlet is high compared to the outlet due to the disturbance and bending loss of the fluid.
Similarly the average velocity shown at the inlet and the outlet of the body.
Total cell count created for the grid size is shown in the above plot.
The above figure shows the mesh, here we using the fixed embedding because of that we get the more element around the throttle body.
Velocity contour:
Pressure Contour:
Velocity Vector:
Throttle visible Geometry:
Streamline:
Velocity at the throttle body:
Explanation of the Contour:
In velocity contour, It is clearly shown that the velocity interact with the throttle and the velocity flow is reduced on the region and it is increased around the corner because area is less compared to the other. In stream line contour it is shown clearly what happened on the throttle. Pressure at the back of the geometry increased since the body is blunt shaped. That area there is possibility of less velocity and rotationality can be formed.
In velocity vector contour (glyph), flow in the throttle area clearly shown it is trying to make a backflow.
Conclusion:
From the above contour and animation, the effect of velocity and the pressure happened on the throttle body is clearly shown for the steady state simulation.