Examination of a large number of experiments dealing with flashing flows in converging and converging-diverging nozzles reveals that knowledge of the flashing inception point is the key to the prediction of critical flow rates. An extension of the static flashing inception correlation of Jones [16] and Alamgir and Lienhard [17] to flowing systems has allowed the determination of the location of flashing inception in nozzle flows with subcooled inlet conditions. It is shown that in all the experiments examined with subcooled inlet regardless of the degree of inlet subcooling, flashing inception invariably occurred very close to the throat. A correlation is given to predict flashing inception in both pipes and nozzles which matches all data available, but is lacking verification in intermediate nozzle geometries where turbulence may be important. A consequence of this behavior is that the critical mass flux may be correlated to the pressure difference between the nozzle inlet and flashing inception, through a single phase liquid discharge coefficient and an accurate prediction of the flashing inception pressure at the throat. Comparison with the available experiments indicate that the predicted mass fluxes are within 5 percent of the measurements.

In view of the importance of obtaining unsteady local void fraction and interface velocities in liquid-vapor two-phase flows, an optical probe with a controlled tip geometry was developed and is described. In order to minimize the disturbances caused to the flow field by the presence of the probe, its dimensions have been miniaturized. The electronic and hydrodynamic responses of the probe were investigated experimentally. The probe was found to be sensitive to both the interface velocities and the phase present at the probe tip. A possible explanation for the behavior of the probe is presented. Within the velocity range checked and with proper calibration, the optical probe described can be used to determine both local void fractions and interface velocities.

By using as sources supersonic jets of hydrogen or helium containing small concentrations of heavier molecules we have been able to obtain molecular beams with kinetic energies of the heavy molecules well into the range above I electron volt. A variety of molecules have been successfully accelerated. Intensities of 10(16) to 10(17) heavy molecules per steradian-second have been achieved at these high energies.

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The aero-thermal performance of a typical turbine blade three-pass turbulated cooling circuit geometry was investigated in a 10X plexiglas test model. The model closely duplicated the blade’s leading edge, midchord and trailing edge cooling passage geometries. Steady state heat transfer coefficient distributions along the blade pressure side wall (convex surface) of the cooling circuit passages were measured with a thin-foil heater and a liquid crystal temperature sensor assembly. The heat transfer experiments were conducted on rib-roughened channels with staggered turbulators along the convex and concave surfaces of the cooling passages. Mid-channel axial velocity and turbulence intensity measurements were taken by hot wire anemometry at each passage end of the three-pass cooling circuit to characterize and relate the local thermal performance to the turbulence intensity levels. The near-atmospheric experimental data are compared with results of a Computational Fluid Dynamics (CFD) analysis at the operating internal environment for a IX rotating model of the blade cooling circuit and other turbulator channel geometry heat transfer data investigations. The comparison between the measurements and analysis is encouraging. Differences with other heat transfer data appear reasonably understood and explainable.

The axial and swirl velocity and turbulence profiles downstream of a small-scale combustor were measured using a Laser Doppler Velocimeter. The effects of combustor geometry (nozzle swirl and liner mixing and dilution holes), operating conditions (mass flow and pressure) and combustion were independently examined. For the combustion tests, the combustor exit temperature profiles were also measured with an insertion thermocouple. The normalized velocity profiles showed no effect of mass flow, pressure or overall velocity on the combustor exit profiles. For the low-swirl fuel nozzle, levels of turbulence were fairly constant without or with combustion. However, with the high-swirl fuel nozzle, the level of swirl decreased as the firing temperature increased (to conserve angular momentum). The effect of swirl reduction could also be seen in the turbulence levels which also decreased. This showed that the mean swirl was generating much of the turbulence. It was also found from testing various combustor geometries that the dilution jets significantly disrupted and thereby reduced the level of swirl exiting from the combustor.

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