Design Considerations for the Closed-Loop Water-Cooled Turbine

One method of liquid-cooling gas turbines is by circulating coolant through a system of radial subsurface passages within the rotating blades. The effect of the large centrifugal force upon the varying-density coolant could cause flow instability or maldistribution problems. Those are discussed and analysis suggests possible stable channel configurations. To efficiently design such a system, it would be necessary to estimate the critical heat flux (CHF) for the coolant channels. Experiments were run to determine CHF during subcooled boiling in rotating tubes with radial inflow, this being the most stable arrangement. The data displays interesting effects peculiar to rotating tubes. Those are explained in terms of the development of secondary flows. A physical model is presented and this provides a rational basis for correlating the CHF data.