Transitional boundary layer parameters in zero and variable pressure gradient flows, typical of turbomachinery applications, are predicted using an integral method of the linear combination type. The code used is that of Dey and Narasimha and the turbulent layer is calculated by a lag-entrainment method. The predictions of test data represent an improvement upon earlier methods; although reasonable agreement is obtained for these low Reynolds number test cases further refinement of predictive correlations to account for free-stream turbulence effects on laminar boundary layers and transition inception is indicated.

The transitional parameters are found to be particularly sensitive to the initial conditions selected for the turbulent layer. Techniques are identified for overcoming this sensitivity and for adequately representing the transition region. Free-stream turbulence effects are quite strong, particularly on the velocity profile of the laminar layer. Modifications to laminar methods are advocated to account for the strong effects on the velocity profile and the early formation of turbulent spots.

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