Analytical and experimental investigation of temperature recovery factors for fully developed flow of air in a tube

W. F. Weiland, W. H. Lowdermilk, R. G. Deissler
Sep 1958

An analysis was made for predicting temperature recovery factors for fully developed flow in a tube. Most of the attention was confined to turbulent flow. Some qualitative results were obtained for laminar flow by setting the eddy diffusivity in the equation for turbulent flow equal to zero and using the incompressible parabolic velocity profile for laminar flow. For zero Mach number the laminar flow results were exact. Radial variation of properties was neglected in most of the calculations. The effect of wall temperature gradient along the tube was negligible for turbulent flow below Mach numbers of 0.9 and 0.98 for Reynolds numbers of 20,000 and 390,000, respectively. For laminar flow the effect became important at much lower Mach numbers. Recovery factors were obtained experimentally for a range of Reynolds number from 630 to 30,000. Additional previously unpublished data are presented for Reynolds numbers up to 650,000. The results indicate that in the turbulent flow region the recovery factor is approximately independent of Reynolds numbers up to 650,000. In the transition region for Reynolds numbers between 2000 and 3000 the recovery factor is reduced abruptly to a value lower than that obtained for the turbulent flow region.

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