Pre-Swirl Blade-Cooling Effectiveness in an Adiabatic Rotor-Stator System

1988 ◽  
Author(s):  
Z. B. El-Oun ◽  
J. M. Owen
Keyword(s):  
Frictional Heating ◽  
Reynolds Numbers ◽  
Rotating Disc ◽  
Reynolds Analogy ◽  
Cooling Effectiveness ◽  
Cooling Flows ◽  
Blade Cooling ◽  
Experimental Errors ◽  
Radial Outflow ◽  
Cooling Air

Blade-cooling air for a high-pressure turbine is often supplied from pre-swirl nozzles attached to a stationary casing. By swirling the cooling air in the direction of rotation of the turbine disc, the temperature of the air relative to the blades can be reduced. The question addressed in this paper is: knowing the temperatures of the pre-swirl and disc-cooling flows, what is the temperature of the blade-cooling air? A simple theoretical model, based on the Reynolds analogy applied to an adiabatic rotor-stator system, is used to calculate the pre-swirl effectiveness (that is, the reduction in the temperature of the blade-cooling air as a result of pre-swirling the flow). A mixing model is used to account for the ‘contamination’ of the blade-coolant with disc-cooling air, and an approximate solution is used to estimate the effect of frictional heating on the disc-cooling air. Experiments were conducted in a rotor-stator rig which had pre-swirl nozzles in the stator and blade-cooling passages in the rotating disc. A radial outflow or inflow of disc-cooling air was also supplied, and measurements of the temperature difference between the pre-swirl and blade-cooling air were made for a range of flow rates and for rotational Reynolds numbers up to Reθ = 1.8 × 106. Considering the experimental errors in measuring the small temperature differences, good agreement between theory and experiment was achieved.

Preswirl Blade-Cooling Effectiveness in an Adiabatic Rotor–Stator System

1989 ◽  
Vol 111 (4) ◽  
pp. 522-529 ◽  
Author(s):  
Z. B. El-Oun ◽  
J. M. Owen
Keyword(s):  
Frictional Heating ◽  
Rotating Disk ◽  
Reynolds Numbers ◽  
Reynolds Analogy ◽  
Cooling Effectiveness ◽  
Cooling Flows ◽  
Blade Cooling ◽  
Experimental Errors ◽  
Radial Outflow ◽  
Cooling Air

Blade-cooling air for a high-pressure turbine is often supplied from preswirl nozzles attached to a stationary casing. By swirling the cooling air in the direction of rotation of the turbine disk, the temperature of the air relative to the blades can be reduced. The question addressed in this paper is: Knowing the temperatures of the preswirl and disk-cooling flows, what is the temperature of the blade-cooling air? A simple theoretical model, based on the Reynolds analogy applied to an adiabatic rotor–stator system, is used to calculate the preswirl effectiveness (that is, the reduction in the temperature of the blade-cooling air as a result of preswirling the flow). A mixing model is used to account for the “contamination” of the blade coolant with disk-cooling air, and an approximate solution is used to estimate the effect of frictional heating on the disk-cooling air. Experiments were conducted in a rotor–stator rig that had preswirl nozzles in the stator and blade-cooling passages in the rotating disk. A radial outflow or inflow of disk-cooling air was also supplied, and measurements of the temperature difference between the preswirl and blade-cooling air were made for a range of flow rates and for rotational Reynolds numbers up to Reθ = 1.8 × 106. Considering the experimental errors in measuring the small temperature differences, good agreement between theory and experiment was achieved.

Heat Transfer in a “Cover-Plate” Pre-Swirl Rotating-Disc System

1998 ◽  
Author(s):  
Robert Pilbrow ◽  
Hasan Karabay ◽  
Michael Wilson ◽  
J. Michael Owen
Keyword(s):  
Heat Transfer ◽  
Reynolds Numbers ◽  
Cover Plate ◽  
Swirl Ratio ◽  
Rotating Disc ◽  
Blade Cooling ◽  
Nusselt Numbers ◽  
Flow And Heat Transfer ◽  
Turbine Disc ◽  
Cooling Air

In most gas turbines, blade-cooling air is supplied from stationary pre-swirl nozzles that swirl the air in the direction of rotation of the turbine disc. In the “cover-plate” system, the pre-swirl nozzles are located radially inward of the blade-cooling holes in the disc, and the swirling air flows radially outwards in the cavity between the disc and a cover-plate attached to it. In this combined computational and experimental paper, an axisymmetric elliptic solver, incorporating the Launder-Sharma and the Morse low-Reynolds-number k-ε turbulence models, is used to compute the flow and heat transfer. The computed Nusselt numbers for the heated “turbine disc” are compared with measured values obtained from a rotating-disc rig. Comparisons are presented, for a wide range of coolant flow rates, for rotational Reynolds numbers in the range 0.5 × 106 to 1.5 × 106, and for 0.9 < βp < 3.1, where βp is the pre-swirl ratio (or ratio of the tangential component of velocity of the cooling air at inlet to the system to that of the disc). Agreement between the computed and measured Nusselt numbers is reasonably good, particularly at the larger Reynolds numbers. A simplified numerical simulation is also conducted to show the effect of the swirl ratio and the other flow parameters on the flow and heat transfer in the cover-plate system.

scholarly journals Flow in a Rotating Cavity With a Peripheral Inlet and Outlet of Cooling Air

1996 ◽  
Author(s):  
Xiaopeng Gan ◽  
Iraj Mirzaee ◽  
J. Michael Owen ◽  
D. Andrew S. Rees ◽  
Michael Wilson
Keyword(s):  
Boundary Layers ◽  
Turbulence Model ◽  
Laser Doppler Anemometry ◽  
Axial Direction ◽  
Reynolds Numbers ◽  
Recirculation Region ◽  
Rotating Disc ◽  
The Core ◽  
Radial Outflow ◽  
Cooling Air

In some engines, corotating gas–turbine discs are cooled by air introduced at the periphery of the system. The air enters through holes in a stationary peripheral casing and leaves through the rim seals between the casing and the discs. This paper describes a combined computational and experimental study of such a system for a range of flowrates and for rotational Reynolds numbers of up to Reϕ = 1.5 × 106. Computations are made using an axisymmetric elliptic solver, incorporating the Launder–Sharma low–Reynolds–number k–ε turbulence model, and velocity measurements are obtained using laser–Doppler anemometry. The stationary peripheral casing creates a recirculation region: there is radial outflow in boundary layers on the discs and inflow in the core between the boundary layers. The radial extent of the recirculation region increases as the flow rate increases and as the rotational speed decreases. In the core, the radial and tangential components of velocity, Vr and Vϕ, are invariant in the axial direction, and the measured values of Vϕ conform to a Rankine–vortex flow. The agreement between the computed and measured velocities is not as good as that found for other rotating–disc systems, and deficiencies in the turbulence model are believed to be responsible.

scholarly journals An Investigation of Ingress for a Simple Shrouded Rotating Disc System With a Radial Outflow of Coolant

1980 ◽  
Author(s):  
J. M. Owen ◽  
U. P. Phadke
Keyword(s):  
Complex Geometry ◽  
Reynolds Numbers ◽  
Turbine Rotor ◽  
Pressure Measurements ◽  
Rotating Disc ◽  
Clearance Ratio ◽  
Gap Ratio ◽  
Radial Outflow ◽  
Cooling Air ◽  
Theoretical Considerations

A plane rotating disc and a plane stator with a cylindrical shroud are used to model the more complex geometry of an air-cooled gas turbine rotor. “Cooling” air, which is supplied to the center of the stator, leaves radially through the clearance between the rotating disc and a stationary shroud, and flow visualization and pressure measurements are used to determine the minimum dimensionless mass flow rate, Cw,min, of cooling air necessary to prevent the ingress of external fluid at the periphery of the system. From theoretical considerations, the results are correlated (for a gap ratio of G = 0.1, shroud clearance ratio between Gc = 0.0025 and Gc = 0.04, and rotational Reynolds numbers between Reθ = 2 × 105 and Reθ = 106) by Cw,min = cGcnReθ

Flow in a “Cover-Plate” Pre-Swirl Rotor-Stator System

1997 ◽  
Author(s):  
Hasan Karabay ◽  
Jian-Xin Chen ◽  
Robert Pilbrow ◽  
Michael Wilson ◽  
J. Michael Owen
Keyword(s):  
Experimental Study ◽  
Vortex Flow ◽  
Reynolds Numbers ◽  
Tangential Component ◽  
Cover Plate ◽  
Rotating Disc ◽  
Blade Cooling ◽  
Rotating Cavity ◽  
Cooling Air ◽  
Nondimensional Temperature

This paper describes a combined theoretical, computational and experimental study of the flow in an adiabatic pre-swirl rotor-stator system. Pre-swirl cooling air, supplied through nozzles in the stator, flows radially outward, in the rotating cavity between the rotating disc and a cover-plate attached to it, leaving the system through blade-cooling holes in the disc. An axisymmetric elliptic solver, incorporating the Launder-Sharma low-Reynolds-number k-ε turbulence model, is used to compute the flow. An LDA system is used to measure the tangential component of velocity, Vϕ, in the rotating cavity of a purpose-built rotating-disc rig. For rotational Reynolds numbers up to 1.2 × 106 and pre-swirl ratios up to 2.5, agreement between the computed and measured values of Vϕ is mainly very good, and the results confirm that free-vortex flow occurs throughout most of the rotating cavity. Computed values of the pre-swirl effectiveness (or the nondimensional temperature difference between the pre-swirl and blade-cooling air) agree closely with theoretical values obtained from a thermodynamic analysis of an adiabatic system.

Flow in a “Cover-Plate” Preswirl Rotor–Stator System

1999 ◽  
Vol 121 (1) ◽  
pp. 160-166 ◽  
Author(s):  
H. Karabay ◽  
J.-X. Chen ◽  
R. Pilbrow ◽  
M. Wilson ◽  
J. M. Owen
Keyword(s):  
Vortex Flow ◽  
Rotating Disk ◽  
Reynolds Numbers ◽  
Tangential Component ◽  
Cover Plate ◽  
Rotating Disc ◽  
Blade Cooling ◽  
Rotating Cavity ◽  
Cooling Air ◽  
Nondimensional Temperature

This paper describes a combined theoretical, computational, and experimental study of the flow in an adiabatic preswirl rotor–stator system. Preswirl cooling air, supplied through nozzles in the stator, flows radially outward, in the rotating cavity between the rotating disk and a cover-plate attached to it, leaving the system through blade-cooling holes in the disk. An axisymmetric elliptic solver, incorporating the Launder–Sharma low-Reynolds-number k–ε turbulence model, is used to compute the flow. An LDA system is used to measure the tangential component of velocity, Vφ, in the rotating cavity of a purpose-built rotating-disc rig. For rotational Reynolds numbers up to 1.2 × 106 and preswirl ratios up to 2.5, agreement between the computed and measured values of Vφ is mainly very good, and the results confirm that free-vortex flow occurs in most of the rotating cavity. Computed values of the preswirl effectiveness (or the nondimensional temperature difference between the preswirl and blade-cooling air) agree closely with theoretical values obtained from a thermodynamic analysis of an adiabatic system.

scholarly journals Heat Transfer From a Rotating Disc

1990 ◽  
Author(s):  
G. H. Dibelius ◽  
M. Heinen
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Rotating Disc ◽  
Reynolds Analogy ◽  
Inlet Swirl ◽  
Additional Influence ◽  
Run Up ◽  
Cooling Air

The local heat transfer from a plane rotating disc enclosed in a casing has been studied experimentally. The disc of 800 mm diameter can be run up to 2000 min−1 at axial distances between disc and casing varied between 5 and 55 mm. Centrifugal or alternatively centripetal flow of cooling air at rates up to ṁ = 1 kg/s can be applied, both with or without an inlet swirl. With the disc rotating in a closed casing (ṁ = 0 kg/s) the influence of the characteristic dimensionless groups on the local heat transfer has been investigated. At a fixed radius, a variation of the local Reynolds Number by either speed or density results in corresponding changes of the heat transfer. However, with a variation of the radius different heat transfer-Re relations are found. In fact, the temperature distribution in the gas caused by the heat flux results in an additional influence of free convection, to be expressed by a Grashof Number. This is confirmed by a comparison of the experimental results with calculations based on Reynolds Analogy and measured friction coefficients. The discrepancies found can be explained only, if in addition to the limitations of the analogy, the influence of free convection is taken into account. Additional results of ongoing experiments concerning the influence of the geometry of the cavity between disc and casing, of the coolant flow rate and of the swirl are presented.

Experimental Study on Racetrack-Shaped Holes Impingement Cooling With Bump Type Roughening Element

2012 ◽  
Author(s):  
Chiyuki Nakamata ◽  
Yoji Okita ◽  
Takashi Yamane ◽  
Yoshitaka Fukuyama ◽  
Toyoaki Yoshida
Keyword(s):  
Experimental Study ◽  
Flow Condition ◽  
Reynolds Numbers ◽  
Main Flow ◽  
The Other ◽  
Relative Location ◽  
Target Plate ◽  
Cooling Effectiveness ◽  
Impingement Cooling ◽  
Cooling Air

Cooling effectiveness of an impingement cooling with array of racetrack-shaped impingement holes is investigated. Two types of specimens are investigated. One is a plain target plate and the other is a plate roughened with bump type elements. Sensitivity of relative location of bump to impingement hole on the cooling effectiveness is also investigated. Experiments are conducted under three different mainflow Reynolds numbers ranging from 2.6×105 to 4.7×105, with four different cooling air Reynolds numbers for each main flow condition. The cooling air Reynolds numbers are in the range from 1.2×103 to 1.3×104.

Heat Transfer in a “Cover-Plate” Preswirl Rotating-Disk System

1999 ◽  
Vol 121 (2) ◽  
pp. 249-256 ◽  
Author(s):  
R. Pilbrow ◽  
H. Karabay ◽  
M. Wilson ◽  
J. M. Owen
Keyword(s):  
Heat Transfer ◽  
Rotating Disk ◽  
Reynolds Numbers ◽  
Turbine Disk ◽  
Cover Plate ◽  
Blade Cooling ◽  
Nusselt Numbers ◽  
Flow And Heat Transfer ◽  
Cooling Air ◽  
Plate System

In most gas turbines, blade-cooling air is supplied from stationary preswirl nozzles that swirl the air in the direction of rotation of the turbine disk. In the “cover-plate” system, the preswirl nozzles are located radially inward of the blade-cooling holes in the disk, and the swirling airflows radially outward in the cavity between the disk and a cover-plate attached to it. In this combined computational and experimental paper, an axisymmetric elliptic solver, incorporating the Launder–Sharma and the Morse low-Reynolds-number k–ε turbulence models, is used to compute the flow and heat transfer. The computed Nusselt numbers for the heated “turbine disk” are compared with measured values obtained from a rotating-disk rig. Comparisons are presented, for a wide range of coolant flow rates, for rotational Reynolds numbers in the range 0.5 X 106 to 1.5 X 106, and for 0.9 < βp < 3.1, where βp is the preswirl ratio (or ratio of the tangential component of velocity of the cooling air at inlet to the system to that of the disk). Agreement between the computed and measured Nusselt numbers is reasonably good, particularly at the larger Reynolds numbers. A simplified numerical simulation is also conducted to show the effect of the swirl ratio and the other flow parameters on the flow and heat transfer in the cover-plate system.

Computation of Heat Transfer in Rotating Cavities Using a Two-Equation Model of Turbulence

1990 ◽  
Author(s):  
A. P. Morse ◽  
C. L. Ong
Keyword(s):  
Heat Transfer ◽  
Turbulence Model ◽  
Radial Direction ◽  
Reynolds Numbers ◽  
Systematic Errors ◽  
Equation Model ◽  
Sufficient Accuracy ◽  
Nusselt Numbers ◽  
Radial Outflow ◽  
Cooling Air

The paper presents finite-difference predictions for the convective heat transfer in symmetrically-heated rotating cavities subjected to a radial outflow of cooling air. An elliptic calculation procedure has been used, with the turbulent fluxes estimated by means of a low Reynolds number k-ε model and the familiar ‘turbulence Prandtl number’ concept. The predictions extend to rotational Reynolds numbers of 3.7 × 106 and encompass cases where the disc temperatures may be increasing, constant or decreasing in the radial direction. It is found that the turbulence model leads to predictions of the local and average Nusselt numbers for both discs which are generally within ± 10% of the values from published experimental data, although there appear to be larger systematic errors for the upstream disc than for the downstream disc. It is concluded that the calculations are of sufficient accuracy for engineering design purposes, but that improvements could be brought about by further optimization of the turbulence model.

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