An experimental research and analysis of using steam for cooling turbine blades

Using steam as a possible coolant for gas turbine blades was investigated as early as 1962 by V. A. Zyzin. Steam has a lower viscosity and relatively higher thermal conductivity compared to air, the most common turbine blade coolant. Successful use of steam as a blade coolant would allow even higher gas turbine operating temperatures, which mean higher operating efficiency. Thus to obtain specific steam heat transfer rate data, Michigan State University's Turbomachinery Lab has built a wind tunnel test stand. This fully instrumented set up has a test cell where turbine blade models can be analyzed. Using this set up and a simple turbine blade model, a series of tests were run which measured the mass flow rate of air and compared it to the mass flow rate of steam.;Using published data for air and steam, a series of plots are presented which compare the fluid properties of air and steam. From these the relative merits of air and steam as blade coolants are discussed. The test data is also plotted and a complete discussion of the results follows.;A theoretical model of a cooled turbine blade is reviewed from which a differential equation of the blade cooling process is derived. This theoretical model and the test results will help predict and aid in the design of further experiments. This data will be available for gas turbine blade designers to utilize steam as a blade coolant.