Abstract
This study numerically examines the effect of actual gas turbine operating conditions on heat transfer characteristics in a ribbed passage with mist/steam cooling. A 60° ribbed passage with aspect ratio of 1/1 was investigated at Reynolds number of 300,000, and steam cooling was used to provide a contrast. Three main factors were considered: coolant temperature, operating pressure, and wall heat flux density. The heat transfer enhancement mechanism of mist/steam cooling was explored, and the results showed that the heat transfer performance of mist/steam cooling was superior to steam cooling. When the coolant temperature varied from 300 to 500 °C, the average Nusselt number of mist/steam cooling decreased by 26.6%, and the heat transfer enhancement ratio dropped from 15% to 10%. As operating pressure increased, the heat transfer performance factor of mist/steam firstly increased and then decreased. At an operating pressure of 1.5 MPa, the heat transfer achieved its optimal performance, and the heat transfer enhancement ratio achieved its maximum value of 15.9%. Larger wall heat flux density provided less heat transfer enhancement. When the heat flux density increased from 100,000 to 300,000 W·m−2, the average Nusselt number of mist/steam cooling decreased by 13.8%, while the heat transfer enhancement ratio decreased from 25.3% to 12.6%.
Highlights
Gas turbines have extensive applications in many important energy production fields, such as aeronautical power, ship propulsion, and power generation
This study examined the heat transfer characteristics in a ribbed passage with mist/steam cooling under actual gas turbine operating conditions
Mist/steam cooling could enhance heat transfer in the ribbed passage under all working conditions used in this study, in contrast to steam cooling
Summary
Gas turbines have extensive applications in many important energy production fields, such as aeronautical power, ship propulsion, and power generation. Research has shown that increasing the inlet temperature of the gas turbine is the main approach to enhance its cycle efficiency and output power [1]. Many scholars are devoted to the research on efficient cooling of gas turbine blades. Back in the 1980s, air was adopted as the coolant for the cooling of gas turbine blades. Many researchers have focused on the influence of air cooling technology on the heat transfer performance of gas turbine blades under different structural parameters or various flow conditions [2,3,4,5]. With the continuous increase in inlet temperature of advanced gas turbines, an increasingly greater amount of cooling air is needed, which will weaken the efficiency of gas turbines
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