Experiment on discharge coefficients for outlet lateral dilated hole

The experimental study on the discharge coefficient of outlet lateral dilated hole was conducted to investigate the trend of discharge coefficients with different structure parameters and aerodynamic parameters.Research showed that the diacharge coefficient of outlet lateral dilated hole cylindrical segment diameter 0.6 mm 3% larger than 0.8 mm.When the hole inclination angle was reduced from 30° to 25°，the discharge coefficient increased，and when the inclination decreased to 20°，the discharge coefficient remains unchanged.When the expansion angle grew from 20° to 40°，the discharge coefficient increased first and then decreased，and reached the maximum value when the expansion angle was 25°.Meanwhile the discharge coefficient was proportional to the secondary flow Reynolds number，and the larger secondary flow Reynolds number indicated the smaller pressure drop needed to reach the limit coefficient value.When the preesure drop was greater than 0.9，the difference of the discharge coefficient at different secondary flow Reynolds number was about 2%.