Disk Heat Transfer Analysis in a Heated Rotating Cavity With an Axial Throughflow

2012 ◽  
Author(s):  
Shuqing Tian ◽  
Yatao Zhu
Keyword(s):  
Heat Transfer ◽  
Boundary Condition ◽  
Rotating Disk ◽  
Outer Wall ◽  
Heat Transfer Analysis ◽  
Outlet Temperature ◽  
Rotating Cavity ◽  
Isothermal Boundary ◽  
Aero Engines ◽  
Cooling Air

In the rotating disk cavities of aero-engine compressors, buoyancy-induced flow and heat transfer can occur due to thermal gradients between cooling air and hot surfaces. The simplified rotating cavity with two plane discs, a shaft and a cylindrical rim has been investigated numerically and compared with the available measurements. Two models have been solved using a commercial CFD code, Fluent, with the RNG k-ε turbulence model. The first one is the conventional model with only fluid region solved, a temperature profile with the linear radial gradient imposed at the disk walls, and an isothermal boundary condition imposed at the shroud wall. The second one is the model with thick-walled disks and shroud, an adiabatic boundary condition imposed at the outer walls of the disks, and an isothermal boundary condition imposed at the outer wall of the shroud. The fluid and solid are coupled solved simultaneously. The disk temperatures are computed. In the present work, the numerical results are in reasonable agreement with the measurements. The computed disk temperatures in the second model have approximately linear radial gradients over the first three-quarters of the disks, and in the last quarter of the disks the temperature radial gradients are obviously non-linear. The different disk temperature profiles in these two models do not lead to obviously different disk heat transfers. The heat transfer in the rotating cavity leads to a considerable temperature increase of the cavity core fluid, therefore a corresponding increase of the outlet temperature. These two temperature increases are critical for the cooling design in aero-engines.

Heat Transfer in a Rotating Cavity With a Stationary Stepped Casing

1999 ◽  
Vol 121 (2) ◽  
pp. 281-287 ◽  
Author(s):  
I. Mirzaee ◽  
P. Quinn ◽  
M. Wilson ◽  
J. M. Owen
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Flow Parameter ◽  
Rotating Disk ◽  
Nusselt Numbers ◽  
Rotating Cavity ◽  
Wide Range ◽  
Heated Disc ◽  
Turbine Disks ◽  
Cooling Air

In the system considered here, corotating “turbine” disks are cooled by air supplied at the periphery of the system. The system comprises two corotating disks, connected by a rotating cylindrical hub and shrouded by a stepped, stationary cylindrical outer casing. Cooling air enters the system through holes in the periphery of one disk, and leaves through the clearances between the outer casing and the disks. The paper describes a combined computational and experimental study of the heat transfer in the above-described system. In the experiments, one rotating disk is heated, the hub and outer casing are insulated, and the other disk is quasi-adiabatic. Thermocouples and fluxmeters attached to the heated disc enable the Nusselt numbers, Nu, to be determined for a wide range of rotational speeds and coolant flow rates. Computations are carried out using an axisymmetric elliptic solver incorporating the Launder–Sharma low-Reynolds-number k–ε turbulence model. The flow structure is shown to be complex and depends strongly on the so-called turbulent flow parameter, λT, which incorporates both rotational speed and flow rate. For a given value λT, the computations show that Nu increases as Reφ, the rotational Reynolds number, increases. Despite the complexity of the flow, the agreement between the computed and measured Nusselt numbers is reasonably good.

Heat Transfer Analysis in a Modern DLN Combustor

2000 ◽  
Author(s):  
Giovanni Ferrara ◽  
Luca Innocenti ◽  
Giacomo Migliorini ◽  
Bruno Facchini ◽  
Anthony J. Dean
Keyword(s):  
Heat Transfer ◽  
Combustion Chamber ◽  
Film Cooling ◽  
Thermal Flux ◽  
Calculation Model ◽  
Heat Transfer Analysis ◽  
Turbine Blade Cooling ◽  
Air Flows ◽  
Critical Components ◽  
Cooling Air

The increasingly stringent emissions standards in recent years have mandated low gas turbine emissions and thus changed the approach to combustion chamber design. In particular, lean burners based on highly premixed fuel-air flows have become more important. These combustors, termed Dry Low NOx (DLN), can now achieve emissions of 25 ppm and below in commercial operation. This development together with the inlet turbine temperature increase has resulted in less cooling air for combustion chambers and turbine blade cooling systems. The designer now needs to optimise cooling air flows that control the wall temperature of the components that confine the hot gases. Moreover, much of the air coming from the compressor is used to premix the fuel and only a smaller fraction is now available for cooling processes. In annular combustor configurations the air available for cooling the combustion chamber walls sometimes also has to cool the first stage nozzle. So the pressure loss along the combustor cooling passages has to be limited in order to assure a suitable supply pressure for these downstream cooling passages. We analysed the cooling air flow around the liner of an annular combustion chamber and we investigated the thermal flux and friction losses. In this paper we show the development of a calculation model that allows the critical components heat transfer analysis of a typical annular combustion chamber. The code developed is based on the generalised 1–D flow treatment. We have used experimental correlations for convection, film cooling and impingement borrowed from works found in literature. The code is provided with a graphical interface that helps the user during the calculation. This code was used in practical application to optimize the PGT5B combustion chamber cooling.

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 Rotating Cavity With a Stationary Stepped Casing

2000 ◽  
Author(s):  
Abdul A. Jaafar ◽  
Fariborz Motallebi ◽  
Michael Wilson ◽  
J. Michael Owen
Keyword(s):  
Heat Transfer ◽  
Cooling System ◽  
Laser Doppler Anemometry ◽  
Tangential Component ◽  
Rotating Disc ◽  
Turbine Engine ◽  
Flow And Heat Transfer ◽  
Rotating Cavity ◽  
Rotating Discs ◽  
Cooling Air

In this paper, new experimental results are presented for the flow in a co-rotating disc system with a rotating inner cylinder and a stationary stepped outer casing. The configuration is based on a turbine disc-cooling system used in a gas turbine engine. One of the rotating discs can be heated, and cooling air is introduced through discrete holes angled inward at the periphery of this disc. The cooling air leaves the system through axial clearances between the discs and the outer casing. Some features of computed flows, and both measured and computed heat transfer, were reported previously for this system. New velocity measurements, obtained using Laser Doppler Anemometry, are compared with results from axisymmetric, steady, turbulent flow computations obtained using a low-Reynolds-number k-ε turbulence model. The measurements and computations show that the tangential component of velocity is invariant with axial location in much of the cavity, and the data suggest that Rankine (combined free and forced) vortex flow occurs. The computations fail to reproduce this behaviour, and there are differences between measured and computed details of secondary flow recirculations. Possible reasons for these discrepancies, and their importance for the prediction of associated heat transfer, are discussed.

scholarly journals Heat Transfer Analysis in a Rotating Cavity with Axial Through-Flow

2021 ◽  
Author(s):  
Mark R Puttock-Brown ◽  
C. A. Long
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Analysis ◽  
Nusselt Numbers ◽  
Analysis Methodology ◽  
Rotating Cavity ◽  
Through Flow ◽  
Stress Relieving ◽  
Inverse Solutions ◽  
Steady State Heat ◽  
The University

Abstract This paper presents local Nusselt numbers computed from experimental measurements of surface temperature of compressor discs in a multiple rotating cavity test rig with axial throughflow. A validated 2D steady state heat conduction analysis methodology is presented, using the actual test geometry, and 95% confidence intervals calculated using Monte Carlo simulation. Sensitivity of the solution to curve fitting types, geometric simplification and surface instrumentation are explored. The results indicate that polynomial curves fits, whilst computational simple, are unsuitable especially at higher orders. It is shown that geometric simplifications, that typically simplify the algorithmic implementation, may also omit significant variation in heat flux at critical stress relieving locations. The effect of reducing measurement points in the analysis is to both over-predict heat transfer and increase the uncertainty of the results. Finally, the methodology is applied to previously published thermal data from the University of Sussex, facilitating qualitative discussion on the influence of the governing parameters. Whilst this study does not overcome the inherent uncertainty associated with inverse solutions it is intended to present a methodology that is readily available to the wider community for the analysis of thermal test data and suggests some guidelines at the planning and post-processing stages.

Ray-Thermal Sequential Coupled Heat Transfer ANALYSIS of Porous Media Receiver for Solar Dish Collector

2013 ◽  
Vol 442 ◽  
pp. 169-175 ◽  
Author(s):  
Fu Qiang Wang
Keyword(s):  
Heat Transfer ◽  
Boundary Condition ◽  
Heat Flux ◽  
Porous Media ◽  
Flux Distribution ◽  
Heat Transfer Analysis ◽  
Uniform Heat Flux ◽  
Heat Flux Distribution ◽  
Uniform Heat ◽  
Distribution Boundary

For the sake of reflecting the concentrated heat flux distribution boundary condition as genuine as possible during simulation, the sequential coupled optical-thermal heat transfer analysis is introduced for porous media receiver. During the sequential coupled numerical analysis, the non-uniform heat flux distribution on the fluid entrance surface of porous media receiver is obtained by Monte-Carlo ray tracing method. Finite element method (FEM) is adopted to solve energy equation using the calculated heat flux distribution as the third boundary condition. The dimensionless temperature distribution comparisons between uniform and non-uniform heat flux distribution boundary conditions, various porosities, and different solar dish concentrator tracking errors are investigated in this research.

Comparison of Continuous and Truncated Ribs on Internal Blade Tip Cooling

2012 ◽  
Author(s):  
Tareq Salameh ◽  
Bengt Sunden
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Turbine Blades ◽  
Ccd Camera ◽  
Outer Wall ◽  
Transfer Coefficients ◽  
Duct Geometry ◽  
Blade Tip ◽  
Cooling Passage ◽  
Cooling Air

In the present work, an experimental study related to turbulent flow inside the bend part of a U-duct geometry was performed concerning pressure drop and heat transfer. Such duct geometries can be found inside gas turbine blades, where the cooling air extracts heat from hot internal walls while it is flowing inside the cooling passage. Both friction factors and convective heat transfer coefficients were established inside the bend part of the U-duct for two different rib cases, namely continuous and truncated ribs with varying Reynolds number from 8,000 to 20,000. For the continuous rib case, the length of the ribs was equal to the height of the duct while in the truncated rib case two different rib lengths, i.e., 46 mm and 40 mm, respectively, were considered. The rib height-to-hydraulic diameter ratio, e/Dh, was 0.1 and the pitch ratio was 10. The test rig has been built in such a way that various experimental setups can be handled as the outer wall of the bend (turn) part of the U-duct can easily be removed and the ribs can be changed. Both the U-duct and the ribs were made from acrylic material to allow optical access for measuring the surface temperature by using a high-resolution measurement technique based on the narrow band thermochromic liquid crystals (TLC R35C5W) and a CCD camera placed facing the bend (turn) part of the U-duct. The calibration of the TLC is based on the hue-based color decomposition system using an in-house designed calibration box. The ribs were placed transversely to the direction of the main flow at the outer wall of the bend (turn) part where the wall was heated by an electrical heater. The pressure drop was almost identical for the continuous and truncated rib cases, while the heat transfer coefficient is 10% higher for the continuous rib case at Re = 20000. The uncertainties in the evaluated properties were 3% and 6% for the Nusselt number and friction factor, respectively.

Flow Visualisation in a Rotating Cavity With Axial Throughflow

2000 ◽  
Author(s):  
Dieter E. Bohn ◽  
Gregor N. Deutsch ◽  
Burkhard Simon ◽  
Claus Burkhardt
Keyword(s):  
Heat Transfer ◽  
Light Sheet ◽  
Video Camera ◽  
Flow Visualisation ◽  
Rotating Cavity ◽  
First Results ◽  
Flow Phenomena ◽  
Set Up ◽  
Cooling Air Flow ◽  
Cooling Air

Annular cavities are found inside rotor shafts of turbomachines with an axial or radial throughflow of cooling air. In order to increase efficiency and system reliability, flow and heat transfer phenomena in those cavities have to be investigated in order to minimize thermal load. For research purposes an experimental rig is set up. This paper focuses on flow visualisation using a laser light sheet technique in a heated rotating cavity which is axially flown through by cooling air. Flow phenomena are observed by a rotating telemetric video camera which shows smoke flowing through the light sheet area located in the axial midplane. The visualisation procedure is described and the first results are pointed out. Additionally, heat transfer measurement across the wall is shown.

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