Influence of Coolant Density on Turbine Blade Platform Film-Cooling

Abstract

Detailed parametric study of film-cooling effectiveness was carried out on a turbine blade platform of a five-blade linear cascade. The parameters chosen were freestream turbulence intensity, upstream stator-rotor purge flow rate, discrete-hole film-cooling blowing ratio, and coolant-to-mainstream density ratio. The measurement technique adopted was temperature sensitive paint (TSP) technique. Two turbulence intensities of 4.2% and 10.5%; three purge flows between the range of 0.25% and 0.75% of mainstream flow rate; three blowing ratios between 1.0 and 1.8; and three density ratios between 1.1 and 2.2 were investigated. Purge flow was supplied via a typical double-toothed stator-rotor seal, whereas the discrete-hole film-cooling was accomplished via two rows of cylindrical holes arranged along the length of the platform. The inlet and the exit Mach numbers were 0.27 and 0.44, respectively. Reynolds number of the mainstream flow was 7.5 * 105 based on the exit velocity and chord length of the blade. Results indicated that platform film-cooling effectiveness decreased with turbulence intensity, increased with purge flow rate and density ratio, and possessed an optimum blowing ratio value.

Improving turbine endwall cooling uniformity by controlling near-wall secondary flows

“…This is discussed by, e.g. Narzary et al., 26 who look at endwall flow patterns with independently varying ψ and J —we see that varying ψ for fixed J alters the streamline pattern on the endwalls.…”

Turbine Blade Film Cooling Using PSP Technique

“…More recently, it has been possible to simulate actual engine density ratios using the PSP mass transfer analogy. (Charbonnier et al (2009) and Narzary et al (2009)). …”

“…The effect of coolant density ratio on film cooling effectiveness was studied by Narzary et al (2009), with the conclusion that higher density coolants are more resilient to lift-off and result in higher film cooling effectiveness.…”

“…This expression (Eq.27) was originally derived by Charbonnier et al (2009), and has been used by Narzary et al (2009) and Rallabandi et al (2010). In the case W f g /W air = 1, Eq.27 reduces to Eq.20.…”

The Aero-Thermal Performance of Purge Flow and Discrete Holes Film Cooling of Rotor Blade Platform in Modern High Pressure Gas Turbines: A Review

“…The former family of experimental facilities may simulate rotation effects through swirl motion or fin introduction. Most of these researches were carried out at Texas A and M University on a five-blade cascade test facility [13][14][15][16][17][18][19][20], at the University of Bergamo on a seven-blade cascade test facility [21][22][23][24][25][26] and at Whittle Laboratory of the University of Cambridge [27,28]. Meanwhile, the latter family of experiments (rotating platforms) were carried out in the TPFL-research turbine facility at Texas A and M University [29,30], in the CT3 compression tube turbine test rig at the von Karman Institute [31], at Ohio State University Turbine Test Facility (TTF) [32][33][34], at the LISA research turbine available at ETH Zurich [35,36] and, more recently, at the Large Annulus Rig (LAR) of the University of Bath [37,38].…”