Under fully developed turbulent flow, the flow coefficient of compressible gas is constant, and that of incompressible gas is smaller than the truth, the error is relative only with pressure ratio.

• 充分发展时，可压缩气体的流量系数恒定不变，不可压缩气体的流量系数比真实值偏小，误差大小只与压力比有关，并随着压力比的增大而增大。