Influence of Wind Tunnel Structure on Static Pressure Coefficient and Static Pressure Gradient of the Test Section

Abstract:

The static pressure coefficient and static pressure gradient are key parameters to estimate the flow quality of automotive wind tunnel test section. Numerical simulation was used along with wind tunnel test to study the influence of wind tunnel structure on static pressure coefficient and static pressure gradient of the test section. It is found that real results can be obtained by simulation of the static pressure coefficient and static pressure gradient using the computational model with two corners. No matter it is big or small nozzle, the static pressure coefficient and static pressure gradient corresponding to the collector height of 270 mm is the gentlest and the effective length of test section is the longest, which has the slightest impact on measurement. For the big nozzle, the static pressure coefficient and static pressure gradient at the position of collector is decreasing constantly with the reduction of the height of collector. When the height of collector is 240 mm, the static pressure coefficient and static pressure gradient close to the collector becomes negative. For the small nozzle, the area of the collector is much larger than that of the nozzle so that the velocity of airflow at the collector decreases, which contributes to a positive value of the local static pressure coefficient and static pressure gradient.