Analysis of modes in rank pipes with round and square cross sections of the working channel

This study compares detailed mode maps during operation using air of two Rank pipes with round and square cross sections of the working channel in the case of identical guides at the inlet and identical outlets. The degree of air expansion and the fraction of flow rate through a cold outlet varies in ranges of 2–8 and 0.2–0.8, respectively. It is observed for both pipes that, as the degree of expansion increases, the dependences of the volumetric flow rate and the cooling coefficient on the fraction of cold flow rate become stable. It is revealed that the cooling coefficient in a round tube is 1.5–2.0 times greater than in a square channel, and the volumetric flow rate therein is approximately 10% lower.