Investigation Into The Aerodynamic Mechanisms For Wind Loads Of Roof-mounted Solar Arrays On A Tall Building By Large Eddy Simulation

Photovoltaic solar panel power generation technology is increasingly applied to urban power supply.For the solar power system installed on the roof of tall buildings,wind load is an important load in the structural design.Most of the existing studies measure the wind pressures by wind tunnel test.There is still lack of in-depth analysis for the aerodynamic mechanisms of wind loads.In this study,large eddy simulation is applied to simulate the wind load of solar arrays on the roof of high-rise building by computational fluid dynamics(CFD).The relationship between the flow field over the roof and the wind load on solar arrays is established.The influence of installation parameters on the wind loads of solar arrays is analyzed.The main content of this study is listed as follows:With ICEM + FLUENT,the CFD model of solar arrays on the roof of tall building was established.The wind field of C-type atmospheric boundary layer was simulated by the CDRFG method.The large eddy simulation(LES)model was used to capture the flow field information.The wind load distributions on both the standalone solar panels and solar arrays were calculated.By comparing with the experimental data,the established model was validated.For a standalone solar panel,negative pressures appeared on the upper and lower surfaces.This was mainly attributed to the separated shear layers and vortices on the roof.The negative pressure is higher at the lower part of the solar panel for downwind directions,while the corner of the solar panel was subjected to larger pressure for oblique wind directions.At 135° wind direction,conical vortices appeared at the corner of the solar panel,which led to large negative pressures on the panel surface.The installation position and inclination angle could apparently affect the wind pressure distribution on the surface of solar panels.With the increase of the distance from the front edge of the building to the solar panel,the absolute value of negative pressures on the surface of the solar panel increased significantly,whereas the net pressure slightly increased.The panel located at the corner of the roof was affected by the conical vortices from the building corners.Hence,the whole panel surface was subjected to the most critical wind loads.When the installation inclination angle became large,the negative pressures on the lower part of the solar panel would increase.When the installation angle became small,the wind pressure distribution on the solar panel surface tended to be flat.For solar arrays,a 3 × 3 panel array acted as obstacles to separate the roof vortex into several parts.The absolute values of negative pressures decreased gradually from the first row of solar arrays to the last row of arrays.Downwind solar panels were mainly affected by the building conical vortices.The net pressures on the main diagonal position of the roof were positive at 45° wind direction,and were negative at 135° wind direction,due to the appearance of secondary conical vortices.The sheltering effect meant a reduction of wind load on solar arrays compared with their standalone counterparts.The sheltering effect was mainly due to the weakening of incoming flow at downwind directions and the destruction of vortex structure at the oblique wind directions.The results showed that the longitudinal spacing of the array affected the wind pressure distribution by influencing the development of negative pressure vortices.The absolute values of negative pressures on the surface of solar arrays increased with the decrease of the longitudinal spacing of the array.The lateral spacing affected the wind pressure distribution by reducing the corners of solar panels,which was beneficial for downwind rows to cancel lateral spacing.