Heat Transfer to Rotating Turbine Blades in a Flow Undisturbed by Wakes (original) (raw)
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Journal of Turbomachinery, 1992
The research described in this paper is a numerical investigation of the effects of unsteady flow on gas turbine heat transfer, particularly on a rotor blade surface. The unsteady flow in a rotor blade passage and the unsteady heat transfer on the blade surface as a result of wake/blade interaction are modeled by the inviscid flow/boundary layer approach. The Euler equations that govern the inviscid flow are solved using a time-accurate marching scheme. The unsteady flow in the blade passage is induced by periodically moving a wake model across the passage inlet. Unsteady flow solutions in the passage provide pressure gradients and boundary conditions for the boundary-layer equations that govern the viscous flow adjacent to the blade surface. Numerical solutions of the unsteady turbulent boundary layer yield surface heat flux values that can then be compared to experimental data. Comparisons with experimental data show that unsteady heat flux on the blade suction surface is well pre...
Unsteady Turbine Blade and Tip Heat Transfer Due to Wake Passing
Volume 4: Turbo Expo 2007, Parts A and B, 2007
The geometry and the flow conditions of the first stage turbine blade of GE’s E3 engine have been used to obtain the unsteady three-dimensional blade and tip heat transfer. The isothermal wall boundary condition was used. The effect of the upstream wake of the first stage vane was of interest and was simulated by provision of a “gust” type boundary condition upstream of the blades. A one blade periodic domain was used. The consequence of this choice was explored in a preliminary study which showed little difference in the time mean heat transfer between a 1:1 and 2:3 vane/blade domains. The full three-dimensional computations are of the blade having a clearance gap of 2% the span. Comparison between the time averaged unsteady and steady heat transfer is provided. It is shown that there is a significant difference between the steady and time mean of unsteady blade heat transfer in localized regions. The differences on the suction side of the blade in the near hub and near tip regions...
Journal of Turbomachinery, 1998
Unsteady wake effects on detailed heat transfer coefficient and film cooling effectiveness distributions from a gas turbine blade with film cooling are obtained using a transient liquid crystal technique. Tests were performed on a five-blade linear cascade at a axial chord Reynolds number of 5.3 × 105 at cascade exit. Upstream unsteady wakes are simulated using a spoke-wheel type wake generator. The test blade has three rows of film holes on the leading edge and two rows each on the pressure and suction surfaces. Air and CO2 were used as coolants to simulate different coolant-to-mainstream density ratio effect. Coolant blowing ratio for air injection is varied from 0.8 to 1.2 and is varied from 0.4 to 1.2 for CO2. Results show that Nusselt numbers for a film-cooled blade are much higher compared to a blade without film injection. Particularly, film injection causes earlier boundary layer transition on the suction surface. Unsteady wakes slightly enhance Nusselt numbers but significa...
TURBINE HEAT TRANSFER AND AERODYNAMIC MEASUREMENTS AND PREDICTIONS FOR A 1.5 STAGE CONFIGURATION
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Effects of Rotation on Blade Surface Heat Transfer: An Experimental Investigation
Journal of Turbomachinery, 1998
Measurements of turbine blade surface heat transfer in a transient rotor facility are compared with predictions and equivalent cascade data. The rotating measurements involved both forward and reverse rotation (wake-free) experiments. The use of thin-film gages in the Oxford Rotor Facility provides both time-mean heat transfer levels and the unsteady time history. The time-mean level is not significantly affected by turbulence in the wake; this contrasts with the cascade response to free-stream turbulence and simulated wake passing. Heat transfer predictions show the extent to which such phenomena are successfully modeled by a time-steady code. The accurate prediction of transition is seen to be crucial if useful predictions are to be obtained.
Experimental Turbine Aero-Heat Transfer Studies in Rotating Research Facilities
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The present paper deals with the experimental aero-heat transfer studies performed in rotating turbine research facilities. Turbine heat transfer research had significant progress in the last few decades. Since the full-scale operational conditions of a modern gas turbine dictate high temperatures well in excess of 3600 o F and pressure ratios ranging from 20 to 50, experimental forced convection heat transfer research on the gas side of a rotating turbine environment is a technically challenging task. The current paper provides a limited review of turbine heat transfer research in various facilities including short-duration blow-down and large-scale/low-speed turbine systems. Since the final status of any forced convection heat transfer problem is closely related to the detailed structure of momentum transfer in highly 3D, unsteady, rotating, and turbulent viscous flow environment, emphasis will also be placed on pertinent turbine aerodynamic features existing in turbines. The most significant parameters to simulate in a rotating aero-heat transfer facility can be listed as Reynolds number based on the blade chord, Mach number for compressibility and shock wave effects, tip speed, intensity and scale of free-stream turbulence, Strouhal number for the unsteady wake passing effects, free-stream to wall temperature ratio, coolant to free-stream temperature ratio, specific heat ratio, molecular Prandtl number of the operating gas and a rotation number for turbine aero heat transfer work performed under rotational conditions. A flow coefficient and a loading coefficient defined by the actual turbine hardware is typically maintained during laboratory testing.
Journal of Turbomachinery, 2010
The effect of the upstream wake on the time averaged rotor blade heat transfer was numerically investigated. The geometry and flow conditions of the first stage turbine blade of GE’s E3 engine with a tip clearance equal to 2% of the span were utilized. The upstream wake had both a total pressure and temperature deficit. The rotor inlet conditions were determined from a steady analysis of the cooled upstream vane. Comparisons between the time average of the unsteady rotor blade heat transfer and the steady analysis, which used the average inlet conditions of unsteady cases, are made to illuminate the differences between the steady and unsteady calculations. To help in the understanding of the differences between steady and unsteady results on one hand and to evaluate the effect of the total temperature wake on the other, separate calculations were performed to obtain the rotor heat transfer and adiabatic wall temperatures. It was found that the Nusselt number distribution for the tim...