Weekly Seminar: Spring 2013
Speaker: Dr. Sumanta Acharya (Louisiana State University)
Title: "Analysis of Film Cooling and the Role of Coolant Pulsations"
Date: Friday, April 19, 2013
Time: 11:00 a.m.
Location: Gilman Hall 50 (Marjorie M. Fisher Hall)
The efficiency of gas turbines used for aero-propulsion and land-based power generation is correlated with the turbine inlet temperature. Modern gas turbines have turbine inlet temperatures in excess of 3000 degrees F that exceed the material limits of the turbine airfoils. Therefore, the first stage airfoils have to be actively cooled. One cooling strategy that is commonly employed is film cooling where coolant air bypassed from the compressor is routed into internal hollow passages in the airfoil and then discharged via discrete holes on the blade surface. The basic unit problem can be considered to be of a coolant jet discharging through a delivery tube at an angle to the surface. There is a large body of literature on this topic.
In this seminar, the dynamics of the film cooling jet issuing from an inclined delivery tube into the crossflow is presented using Direct Numerical Simulations (DNS) and Large Eddy Simulations (LES). The energetic modes that contribute to the cooling of the surface are identified and analysed. The effect of uncertainty in the velocity ratio (i.e., ratio of coolant jet velocity to mainstream flow velocity) on the cooling effectiveness is studied from a probabilistic point of view. Finally, the role of coolant pulsations on the cooling effectiveness is examined by varying the two parameters of duty cycle and time period of the pulsations. A response-function strategy of identifying the global and local optima in cooling effectiveness in the two-parameter space of duty cycle and time period is presented and discussed.
Dr. Acharya has been on the faculty of mechanical engineering at Louisiana State University since 1982 where he is the L. R. Daniel Professor and the Director of Turbine Innovation & Energy Research (TIER) Center. His interests are in computational fluids, gas turbine heat transfer and combustion, and he has published or presented nearly 185 journal articles and book chapters and over 225 refereed conference papers on these and related fields. He has supervised the work of nearly 60 graduate students and has been a principal investigator (PI) or co-PI of nearly $25 million of funded research. He is the recipient of the ASME Heat Transfer Memorial Award, the LSU Distinguished Research Master Award, and three best-teacher awards from students. He is currently at the National Science Foundation as the Program Director of the Thermal Transport Process in the Chemical, Bio-Engineering, Environmental and Transport (CBET) Division.