Comparison of Calculated and Measured Heat Transfer Coefficients for Transonic and Supersonic Boundary-Layer Flows

Abstract

The present study compares measured and computed heat transfer coefficients for high speed boundary layer nozzle flows under engine Reynolds-number conditions (U∞ = 230 ÷ 880 m/s, Re* = 0.37 ÷ 1.07 · 106). Experimental data have been obtained by heat transfer measurements in a two-dimensional, non-symmetric, convergent-divergent nozzle. The nozzle wall is convectively cooled using water passages. The coolant heat transfer data and nozzle surface temperatures are used as boundary conditions for a three-dimensional finite-element code which is employed to calculate the temperature distribution inside the nozzle wall. Heat transfer coefficients along the hot gas nozzle wall are derived from the temperature gradients normal to the surface. The results are compared with numerical heat transfer predictions using the low Reynolds-number k-ε turbulence model by Lam and Bremhorst. Influence of compressibility in the transport equations for the turbulence properties is taken into account by using the local averaged density. The results confirm that this simplification leads to good results for transonic and low supersonic flows.

The optimization of rough surface supersonic nozzles

“…Hoffman [2] studied conical nozzles with nonisentropic flow, without considering a variable geometry. Hurst et al [3] developed experiments and calculated numerically heat transfer coefficients along the hot gas nozzle smooth wall for high-speed boundary layer nozzle flows under engine Reynolds number conditions, presenting a comparison between the experimental and numerical results, showing that the simplification of a local average density in the numerical model leads to good results for transonic and low supersonic flows. Zaccaria et al [4] performed experiments to determine the three-dimensional flowfield in the nozzle of a low-speed, single-stage, axial-flow turbine, comparing the measurements to the numerical results of an existing Navier-Stokes code with good agreement, basically seeking a better understanding of the nozzle flowfield.…”