Loss measurements and interpretation of Pitot pressures in two-phase vapor-droplet flow

An analysis of the nonequilibrium processes that take place near the mouth of a Pitot probe inserted in a two-phase vapor-droplet flow is presented. The correction that must be applied to recorded Pitot pressures to account for nonequilibrium effects is shown to have a significant bearing on the inferred values of loss. Attention is focused on supersonic wet-steam flow, for which the analysis is supported by comparison between predicted and measured energy-loss coefficients. However, extension of the method to deal with any particle-or droplet-laden flow should be straightforward. Corrected measurements of loss coefficient are presented for a cascade of steam turbine stator blades at a range of conditions, highlighting the importance of condensation as a loss-generating mechanism. (C) Elsevier Science Inc., 1997.