Turbine Vane Endwall Film Cooling Comparison From Five Film-Hole Design Patterns and Three Upstream Injection Angles

Abstract

The effects of upstream injection angle on film cooling effectiveness of a turbine vane end wall with various endwall film-hole designs were examined by applying pressure-sensitive paint (PSP) measurement technique. As the leakage flow from the slot between the combustor and the turbine vane is not considered an active source to protect the vane endwall in certain engine designs, discrete cylindrical holes are implemented near the slot to create an additional controllable upstream film to cool the vane end wall. Three potential injection angles were studied: 30 deg, 40 deg, and 50 deg. To explore the optimum endwall cooling design, five different film-hole patterns were tested: axial row, cross row, cluster, midchord row, and downstream row. Experiments were conducted in a four-passage linear cascade facility in a blowdown wind tunnel at the exit isentropic Mach number of 0.5 corresponding to inlet Reynolds number of 380,000 based on turbine vane axial chord length. A freestream turbulence intensity of 19% with an integral length scale of 1.7 cm was generated at the cascade inlet plane. Detailed film cooling effectiveness for each design was analyzed and compared at the design operation conditions (coolant mass flow ratio (MFR) 1% and density ratio 1.5). The results are presented in terms of high-fidelity film effectiveness contours and laterally (spanwise) averaged effectiveness. This paper will provide the gas turbine designers valuable information on how to select the best endwall cooling pattern with minimum cooling air consumption over a range of upstream injection angle.

Turbine vane endwall aerothermal and film cooling performance considering realistic swirling inflow conditions

“…The confidence level is 95% for the EXP result and the uncertainties of η=0.1,0.3,0.5,0.7 are 12%, 5.4%, 3.1%, 2.2%, respectively. 21 The comparison of the η distribution on the endwall among EXP and CFD results is presented in Figure 11. The η downstream of each row film hole has been predicted more accurately by SST k−ω turbulence model than by the other three models.…”

Effects of Anticlockwise Swirling Inflow on the Aerothermal Performance of the Turbine Vane Endwall with Film Cooling Layouts

“…Figure 1 shows the experimental vane cascade model from (Shiau et al, 2019) of the Turbine Laboratory of Texas A&M University. Table 1 lists the main geometric parameters of the experimental vane cascade and film holes.…”

“…The aerodynamic and cooling performance of the turbine vane endwall was given by (Friedrichs et al, 1997) and they pointed out that the film cooling layout of the endwall needs to consider the complicated secondary flow vortex structure and the intermixing effect of mainflow and film cooling airflow. In (Shiau et al 2019), they used linear cascade experiments to study the heat transfer and cooling performance of the endwall with 3 rows of upstream film holes and 5 film cooling layouts. The results showed that the film cooling layout combined with the development characteristics of the secondary flow vortex system on the endwall had the excellent cooling performance.…”

Experimental investigation of the influence of density ratio and vane exit mach number on platform cooling

“…Shifting attention to the platform cooling inside of the passage, Shiau and his coauthors addressed several topics by applying PSP. In Shiau et al (2019), a combination between three upstream injection angles and five film-hole design patterns was experimentally tested, under fixed mainstream (Ma2is = 0.5, Tu1 = 19%) and coolant condition (MFR = 1%, DR = 1.5). Although each endwall film-hole pattern was found to have its unique flow/pressure distribution, the general rule is that the thermal coverage provided by the cooling holes located upstream of the throat is heavily dependent on the capability to suppress the secondary flows.…”