Abstract
Some examples are described of premature nonconvergence and resulting loss of solution of an iterative computer-based procedure for predicting the off-design performance data of an axial-flow pump. Caution in interpreting nonconvergence in similar procedures is suggested. A brief description is given of how the axisymmetric, constant density, steady, adiabatic, locally inviscid blade-element flow model subject to the simple radial-equilibrium condition is used as the basis of the present computation procedure with losses and deviation angles based on correlations of numerous pump rotor data. The base velocity estimation procedures, as well as the loss and deviation angle calculation methods used, are shown to have significant influence on solution convergence. While the examples described are specific, it is believed that the related conclusions are generally applicable to turbomachine flows involving large blade-row exit axial velocity gradients and/or near-zero local axial velocities.
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