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The problems in water-cooled rotors have centered around the high pressuies generated in a closed circuit containing water by the high centrifugal field. The present program focusses on open circuit water cooling in which the water has been allowed to exit freely from the bucket tips. This eliminates the leaks and plugging of cooling channels that have been encountered before permits one to distribute the coolant uniformly around the bucket airfoil contour close to the surface. In this way the thermal gradients and thermal stresses on the airfoil can be held within safe limits. Using this approach a 9.7 in. (24.7 cm) diameter turbine wheel has been built and operated at inlet conditions of 2850 F (1560 C) and 16 atmosphere with tip speeds in excess of 1700 fps (518 m/sec) and with good aerodynamic efficiency. Recent developments in ceramic materials also indicate potential for use in stationary parts.

The conductivity of the hot gases from propane-oxygen flames containing potassium has been measured in a coaxial graphite cell. In the temperature range 1800–2400°K with potassium concentrations of 0.01–1.0% by weight, the measured conductivity agrees with that calculated from the Saha equation and a ``free-path'' kinetic equation. A constant value of 1×10−15 cm2 was used as the cross section for collision between electrons and the combustion products in this calculation. At higher potassium concentrations, up to 7½% by weight, the electron-potassium atom cross section becomes important but a value of about 10−15 cm2 gives fair agreement with the data. At low temperatures and high cell voltages, current saturation resulting from the limited electron emissivity of the graphite was observed.

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An x-ray absorption photometer capable of measuring gas densities with extreme rapidity and reasonable accuracy has been developed to study the reaction zone in detonation waves. At low initial gas pressures this zone is readily observable as a density peak at the wave front lasting a few ,.,sec.In general the results agree with the hydrodynamic theory of the detonation wave. The observed densities at the end of the reaction zone (the Chapman-Jouguet state) compare well with the results of approximate equilibrium calculations and the observed shape of the density profile qualitatively confirms kinetic predictions. However, the observed peak densities are substantially lower than expected and the initial chemical reaction rates are faster. The most plausible explanation at present seems to be a lack of equilibration between translational and internal degrees of freedom in the shocked gas, lasting long enough for a substantial progress of the chemical reactions to take place.The duration of the reaction zone in the mixtures studied is