Real case simulation of Solar Tracker using CFD

Open Domain simulation

A real case dimension of solar panel is considered for the simulation. Since it is an open domain simulation the boundary condition were based on well-posed boundary condition. In that case here in my simulation domain dimensions are 40*30*15. And solar panel dimensions are 3*4*0.03 meter and height of the support beam is 2.2 m; radius of beam is 0.168 m. wind velocity is assumed as to be 20 m/s and panel was tilted to 35 degree. Two panels were put placed together like closer to the reality case. The distance between the two panels is 1.5 *length of the solar panel which is 4 m.

Numerical simulation setup

Fig 1 Pressure distribution on the panel

Geometry of the model or domain is created using the Ansys design modeler later it is transported in to the ICED CFD for the meshing (structured mesh hexahedron elements). There were some problem in ICEM CFD when I try to transfer the mesh to CFX; mostly it was like coordinates changes and domain size is changes automatically that causes more trouble when to try to set a velocity profile in CFX. So I used mostly unstructured mesh from the ansys. And in that also there were a little problem with 8GB memory size of the computer. It was taking some time for the meshing calculation and it crashes too some time for example, if the elements goes to more than, 8 million elements. Mesh independence were also tested to see the minimum required elements for the simulation. In the beginning I started with course mesh and further the domain is refined until it gets the mesh independence. Mostly there were slightly variations in the velocity and pressure difference between the coarse and fine mesh closer to the solar pane; it is mainly due to the turbulence behavior of the fluid flow where we need to have good mesh to get a good solution. So the mesh is refined closer to the solar panel. Y-plus values are important to predict the flow behavior closer to the wall. Inflated layer is used to around the walls to have better Y-plus value. For this model the simulation is done in transient type and the courant number is set to closer to one.Simulations were done using the prelog super computer

Fig 2 Velocity contour

Inlet velocity is based on the wind profile power law. The reference height is 2.2 m and velocity is 20 m/s. the velocity will be higher above than the 2.2 m and it will be gradually decreases in to 0 m/s where the flow meets the bottom wall. In Ansys this inlet boundary condition is expressed in terms of expression. Inlet pressure boundary condition is initialized based on the compressible flow; it is calculated using the ratio of specific heat capacity, Mach number and static pressure. Outlet boundary condition is set to zero static pressure. Bottom wall and solar panel were defined as no-slip wall and other walls named as free-slip wall (the velocity at the walls will  be same as the fluid).

Fig 3 Velocity streamline

In Fig 1.pressure contour shows the how the pressure acts on the solar panel due the wind speed. As we can see the fist panel faces the more pressure than the second one. The velocity contour Fig 2.shows the velocity in the domain. In Fig 3.the streamline velocity small vortex is formed behind the first solar panel than in the second one; this is because the first one faces the more air flow than the second one.A very soon different angle of air flow attack and wind tunnel data will be compared and validated.