626. CORCORAN, W. H., ROUDEBUSH, B., AND SAGE, B. H. Temperature Gradients in Turbulent Gas Streams. Preliminary Studies. Chem. Eng. Progress, vol. 43, 1947, pp. 135-142. Equipment is described that permits measurement of the temperature and velocity distribution in an air stream with essentially w-dimensional flow characteristics. Preliminary results, including data describing the temperature and velocity distribution, heat transfer from the wall, and shearing stress, are submitted for 7 different sets of conditions. The data indicate that, within the accuracy of measurement, the eddy viscosity and eddy conductivity are equal, as was assumed by von Karman in his analogy between the transfer of momentum and the thermal transfer of energy. The over-all heat-transfer rate predicted by the Karman analogy agrees with the experimental results in the case of a symmetrical temperature distribution. However, significant divergences from the heat-transfer rates predicted by the analogy were experienced in the case of nonsymmetric temperature distributions. The results presented are of a preliminary nature and not of sufficient extent to permit the experimental uncertainty to be established definitely. The detailed study of temperature and velocity distribution together with the associated heat transfer and shearing stress permits a microscopic evaluation of the thermal transfer of energy through a turbulently flowing air stream. The methods employed appear to be capable of refinement, and further study of thermal transfers of energy by these and related methods should permit ultimately the more accurate prediction of the rate of thermal transfers of energy for situations where the transfers of momentum can be predicted from the science of fluid mechanics. CORDINER, J. B. See abs. 3305a, 3306. COREY, R. C. See abs. 810a, 2615. |