Experimental study on flow and heat transfer in circular small-scale channels for aeroengines

Heat transfer and flow characteristics of fully-developed nitrogen-fluid flowing through small-scale channels of a circular cross section were investigated experimentally in this paper. Experiments were conducted with the diameter of channels varying from 0.3 to 0.8mm and the length from 50 to 300mm. and Reynolds number up to 5000. Heat transfer coefficients, h, and Nusselt numbers, Nu, and also the frictional factors. f. for. three channels were acquired. Furthermore, the measured Nusselt number and the frictional factor were compared to the classical correlations and the suggested microscale correlations. Experimental results were given that the diameter and the length of circular small-scale channels were important factors; as the diameter was decreased, h and f were increased, and/was increased with the length decreased. Comparisons showed that the frictional factor for small-scale channels was larger than that for macroscale channels, and the suggested microscale correlation were not in agreement with the obtained experimental data, especially in region of larger Reynolds number.