scholarly journals Performance of Pre-Swirl Rotating-Disc Systems

1999 ◽  
Author(s):  
Hasan Karabay ◽  
Robert Pilbrow ◽  
Michael Wilson ◽  
J. Michael Owen
Keyword(s):  
Heat Transfer ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Tangential Velocity ◽  
Turbulence Models ◽  
Cover Plate ◽  
Swirl Ratio ◽  
Rotating Disc ◽  
Blade Cooling ◽  
Cooling Air

This paper summarises and extends recent theoretical, computational and experimental research into the fluid mechanics, thermodynamics and heat transfer characteristics of the so-called cover-plate pre-swirl system. Experiments were carried out in a purpose-built rotating-disc rig, and the Reynolds-averaged Navier-Stokes equations were solved using 2D (axisymmetric) and 3D computational codes, both of which incorporated low-Reynolds-number k-ε turbulence models. The free-vortex flow, which occurs inside the rotating cavity between the disc and cover-plate, is controlled principally by the pre-swirl ratio, βp: this is the ratio of the tangential velocity of the air leaving the nozzles to that of the rotating disc. Computed values of the tangential velocity are in good agreement with measurements, and computed distributions of pressure are in close agreement with those predicted by a one-dimensional theoretical model. It is shown theoretically and computationally that there is a critical pre-swirl ratio, βp,crit, for which the frictional moment on the rotating discs is zero, and there is an optimal pre-swirl ratio, βp,opt, where the average Nusselt number is a minimum. Computations show that, for βp < βp,opt, the temperature of the blade-cooling air decreases as βp increases; for βp > βp,opt, whether the temperature of the cooling air increases or decreases as βp increases depends on the flow conditions and on the temperature difference between the disc and the air. Owing to the three-dimensional flow and heat transfer near the blade-cooling holes, and to unquantifiable uncertainties in the experimental measurements, there were significant differences between the computed and measured temperatures of the blade-cooling air. In the main, the 3D computations produced smaller differences than the 2D computations.

Performance of Pre-Swirl Rotating-Disc Systems

2000 ◽  
Vol 122 (3) ◽  
pp. 442-450 ◽  
Author(s):  
Hasan Karabay ◽  
Robert Pilbrow ◽  
Michael Wilson ◽  
J. Michael Owen
Keyword(s):  
Heat Transfer ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Tangential Velocity ◽  
Cover Plate ◽  
Two Dimensional ◽  
Swirl Ratio ◽  
Rotating Disc ◽  
Blade Cooling ◽  
Cooling Air

This paper summarizes and extends recent theoretical, computational, and experimental research into the fluid mechanics, thermodynamics, and heat transfer characteristics of the so-called cover-plate pre-swirl system. Experiments were carried out in a purpose-built rotating-disc rig, and the Reynolds-averaged Navier-Stokes equations were solved using two-dimensional (axisymmetric) and three-dimensional computational codes, both of which incorporated low-Reynolds-number k-ε turbulence models. The free-vortex flow, which occurs inside the rotating cavity between the disc and cover-plate, is controlled principally by the pre-swirl ratio, βp: this is the ratio of the tangential velocity of the air leaving the nozzles to that of the rotating disc. Computed values of the tangential velocity are in good agreement with measurements, and computed distributions of pressure are in close agreement with those predicted by a one-dimensional theoretical model. It is shown theoretically and computationally that there is a critical pre-swirl ratio, βp,crit, for which the frictional moment on the rotating discs is zero, and there is an optimal pre-swirl ratio, βp,opt, where the average Nusselt number is a minimum. Computations show that, for βp<βp,opt, the temperature of the blade-cooling air decreases as βp increases; for βp>βp,opt, whether the temperature of the cooling air increases or decreases as βp increases depends on the flow conditions and on the temperature difference between the disc and the air. Owing to the three-dimensional flow and heat transfer near the blade-cooling holes, and to unquantifiable uncertainties in the experimental measurements, there were significant differences between the computed and measured temperatures of the blade-cooling air. In the main, the three-dimensional computations produced smaller differences than the two-dimensional computations. [S0742-4795(00)01902-5]

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.

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.

Flow and Heat Transfer in a Preswirl Rotor–Stator System

1997 ◽  
Vol 119 (2) ◽  
pp. 364-373 ◽  
Author(s):  
M. Wilson ◽  
R. Pilbrow ◽  
J. M. Owen
Keyword(s):  
Heat Transfer ◽  
Gas Turbines ◽  
Heat Fluxes ◽  
Valuable Insight ◽  
Swirl Ratio ◽  
Blade Cooling ◽  
Nusselt Numbers ◽  
Air Temperatures ◽  
Via Holes ◽  
Cooling Air

Conditions in the internal-air system of a high-pressure turbine stage are modeled using a rig comprising an outer preswirl chamber separated by a seal from an inner rotor-stator system. Preswirl nozzles in the stator supply the “blade-cooling” air, which leaves the system via holes in the rotor, and disk-cooling air enters at the center of the system and leaves through clearances in the peripheral seals. The experimental rig is instrumented with thermocouples, fluxmeters, pitot tubes, and pressure taps, enabling temperatures, heat fluxes, velocities, and pressures to be measured at a number of radial locations. For rotational Reynolds numbers of Reφ ≃ 1.2 × 106, the swirl ratio and the ratios of disk-cooling and blade-cooling flow rates are chosen to be representative of those found inside gas turbines. Measured radial distributions of velocity, temperature, and Nusselt number are compared with computations obtained from an axisymmetric elliptic solver, featuring a low-Reynolds-number k–ε turbulence model. For the inner rotor-stator system, the computed core temperatures and velocities are in good agreement with measured values, but the Nusselt numbers are underpredicted. For the outer preswirl chamber, it was possible to make comparisons between the measured and computed values for cooling-air temperatures but not for the Nusselt numbers. As expected, the temperature of the blade-cooling air decreases as the inlet swirl ratio increases, but the computed air temperatures are significantly lower than the measured ones. Overall, the results give valuable insight into some of the heat transfer characteristics of this complex system.

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.

scholarly journals Flow and Heat Transfer in a Pre-Swirl Rotor-Stator System

1995 ◽  
Author(s):  
Michael Wilson ◽  
Robert Pilbrow ◽  
J. Michael Owen
Keyword(s):  
Heat Transfer ◽  
Gas Turbines ◽  
Heat Fluxes ◽  
Valuable Insight ◽  
Swirl Ratio ◽  
Blade Cooling ◽  
Nusselt Numbers ◽  
Swirl Chamber ◽  
Air Temperatures ◽  
Cooling Air

Conditions in the internal-air system of a high-pressure turbine stage are modelled using a rig comprising an outer pre-swirl chamber separated by a seal from an inner rotor-stator system. Pre-swirl nozzles in the stator supply the “blade-cooling” air, which leaves the system via holes in the rotor, and disc-cooling air enters at the centre of the system and leaves through clearances in the peripheral seals. The experimental rig is instrumented with thermocouples, fluxmeters, pitot tubes and pressure taps enabling temperatures, heat fluxes, velocities and pressures to be measured at a number of radial locations. For rotational Reynolds numbers of Reϕ ≃ 1.2 × 106, the swirl ratio and the ratios of disc-cooling and blade-cooling flow rates are chosen to be representative of those found inside gas turbines. Measured radial distributions of velocity, temperature and Nusselt number are compared with computations obtained from an axisymmetric elliptic solver, featuring a low-Reynolds-number k-ε turbulence model. For the inner rotor-stator system, the computed core temperatures and velocities are in good agreement with measured values, but the Nusselt numbers are underpredicted. For the outer pre-swirl chamber, it was possible to make comparisons between the measured and computed values for cooling-air temperatures but not for the Nusselt numbers. As expected, the temperature of the blade-cooling air decreases as the swirl ratio increases, but the computed air temperatures are significantly lower than the measured ones. Overall, the results give valuable insight into some of the heat transfer characteristics of this complex 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 A Code for Simulating Heat Transfer in Turbulent Channel Flow

Mathematics ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 756
Author(s):  
Federico Lluesma-Rodríguez ◽  
Francisco Álcantara-Ávila ◽  
María Jezabel Pérez-Quiles ◽  
Sergio Hoyas
Keyword(s):  
Heat Transfer ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Turbulent Channel Flow ◽  
Passive Scalar ◽  
Direct Numerical Simulations ◽  
Time Dependent ◽  
Navier Stokes ◽  
Thermal Flow ◽  
Navier Stokes Equations

One numerical method was designed to solve the time-dependent, three-dimensional, incompressible Navier–Stokes equations in turbulent thermal channel flows. Its originality lies in the use of several well-known methods to discretize the problem and its parallel nature. Vorticy-Laplacian of velocity formulation has been used, so pressure has been removed from the system. Heat is modeled as a passive scalar. Any other quantity modeled as passive scalar can be very easily studied, including several of them at the same time. These methods have been successfully used for extensive direct numerical simulations of passive thermal flow for several boundary conditions.

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.

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