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.

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.

Coupling of Convective and Radiative Heat Transfer in PV Cooling Ducts

2002 ◽  
Vol 124 (3) ◽  
pp. 250-255 ◽  
Author(s):  
B. J. Brinkworth
Keyword(s):  
Heat Transfer ◽  
Turbulent Flows ◽  
Radiative Heat ◽  
Radiation Exchange ◽  
Axial Temperature ◽  
Pv Cooling ◽  
Cooling Air Flow ◽  
Cooling Air ◽  
Cooling Ducts ◽  
Laminar And Turbulent Flows

In a PV cooling duct, heat transfer from the heated side to the cooling air flow takes place partly by convection at the walls and partly by radiation exchange between them. A method is developed for representing these effects in combination, avoiding the uncertainties and iterations involved in treating the two mechanisms as independent and parallel. Though the radiative element introduces two further parameters, the procedure has a straightforward closed form, convenient for routine engineering calculations. An approximation, that treats the radiation exchange as determined by the local wall temperatures, is validated by comparison with published results in which the diffusion due to the axial temperature distribution is fully represented. The method is applicable to both laminar and turbulent flows, employing coefficients already available in the literature. The incorporation of duct heat transfer within thermal models of the PV installation is discussed briefly, highlighting further areas which are being refined by on-going work.

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.

Numercial Simulation of Sinter Cooling Process

2010 ◽  
Author(s):  
Fengguo Tian ◽  
D. Frank Huang ◽  
Chenn Q. Zhou
Keyword(s):  
Heat Transfer ◽  
Initial Temperature ◽  
Air Flow ◽  
Convection Heat Transfer ◽  
Cooling Process ◽  
Initial Temperature Distribution ◽  
Cooling Air Flow ◽  
Sinter Cooler ◽  
Cooling Air ◽  
Cooling Model

A 2-D sinter cooling model is built to simulate the hot iron ore sinter cooling process in a sinter cooler. In this model the convection heat transfer is applied for the heat transfer between the sinter particle skin and the cooling air flow. Thermal conduction is used for the heat conduction within the sinter particles, and fluid dynamics is applied tothe cooling gas distributions. This model will be able to analyze the effects of sinter particle size, size distribution, hot sinter initial temperature, initial temperature distribution, sinter cooler size, cooler configuration and cooling air flow rate as well as cooling air temperature on the sinter cooling process. In this paper the 2-D sinter cooling model is presented along with certain parametric study examples.

ICAS-GT: A European Collaborative Research Programme on Internal Cooling Air Systems for Gas Turbines

2002 ◽  
Author(s):  
Peter D. Smout ◽  
John W. Chew ◽  
Peter R. N. Childs
Keyword(s):  
Heat Transfer ◽  
Gas Turbines ◽  
Research Programme ◽  
Cavity Flow ◽  
Internal Cooling ◽  
Manufacturing Companies ◽  
Flow And Heat Transfer ◽  
Rotating Cavity ◽  
Internal Fluid Flow ◽  
Cooling Air

The Internal Cooling Air Systems for Gas Turbines (ICAS-GT) research programme, sponsored by the European Commission, ran from January 1998 to December 2000, and was undertaken by a consortium of ten gas turbine manufacturing companies and four universities. Research was concentrated in five discrete but related areas of the air system including turbine rim seals, rotating cavity flow and heat transfer, and turbine pre-swirl system effectiveness. In each case, experiments were conducted to extend the database of pressure, temperature, flow and heat transfer measurements to engine representative non-dimensional conditions. The data was used to develop correlations, and to validate CFD and FE calculation methods, for internal fluid flow and heat transfer. This paper summarises the outcome of the project by presenting a sample of experimental results from each technical work package. Examples of the associated CFD calculations are included to illustrate the progress made in developing validated tools for predicting rotating cavity flow and heat transfer over an engine representative range of flow conditions.

Rotating Cavity With Axial Throughflow of Cooling Air: Heat Transfer

1992 ◽  
Vol 114 (1) ◽  
pp. 229-236 ◽  
Author(s):  
P. R. Farthing ◽  
C. A. Long ◽  
J. M. Owen ◽  
J. R. Pincombe
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Simple Correlation ◽  
Nusselt Numbers ◽  
Rotating Cavity ◽  
Wide Range ◽  
Effects Of Radiation ◽  
Increasing Temperature ◽  
Cooling Air ◽  
Made In

Heat transfer measurements were made in two rotating cavity rigs, in which cooling air passed axially through the center of the disks, for a wide range of flow rates, rotational speeds, and temperature distributions. For the case of a symmetrically heated cavity (in which both disks have the same temperature distribution), it was found that the distributions of local Nusselt numbers were similar for both disks and the effects of radiation were negligible. For an asymmetrically heated cavity (in which one disk is hotter than the other), the Nusselt numbers on the hotter disk were similar to those in the symmetrically heated cavity but greater in magnitude than those on the colder disks; for this case, radiation from the hot to the cold disk was the same magnitude as the convective heat transfer. Although the two rigs had different gap ratios (G = 0.138 and 0.267), and one rig contained a central drive shaft, there was little difference between the measured Nusselt numbers. For the case of “increasing temperature distribution” (where the temperature of the disks increases radially), the local Nusselt numbers increase radially; for a “decreasing temperature distribution,” the Nusselt numbers decrease radially and become negative at the outer radii. For the increasing temperature case, a simple correlation was obtained between the local Nusselt numbers and the local Grashof numbers and the axial Reynolds number.

scholarly journals Heat Transfer Measurements in an Annular Cascade of Transonic Gas Turbine Blades Using the Transient Liquid Crystal Technique

1994 ◽  
Author(s):  
R. F. Martinez-Botas ◽  
G. D. Lock ◽  
T. V. Jones
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Liquid Crystal ◽  
Transfer Coefficient ◽  
Turbine Blades ◽  
Video Camera ◽  
Flow Visualisation ◽  
Annular Cascade ◽  
Transient Liquid Crystal Technique ◽  
The Heat Transfer Coefficient

Heat transfer measurements have been made in the Oxford University Cold Heat Transfer Tunnel employing the transient liquid crystal technique. Complete contours of the heat transfer coefficient have been obtained on the aerofoil surfaces of a large annular cascade of high pressure nozzle guide vanes (mean blade diameter of 1.11 m and axial chord of 0.0664 m). The measurements are made at engine representative Mach and Reynolds numbers (exit Mach number 0.96 and Reynolds number 2.0 × 106). A novel mechanism is used to isolate five preheated blades in the annulus before an unheated flow of air passes over the vanes, creating a step change in heat transfer. The surfaces of interest are coated with narrow-band thermochromic liquid crystals and the colour crystal change is recorded during the run with a miniature CCD video camera. The heat transfer coefficient is obtained by solving the one dimensional heat transfer equation for all the points of interest. This paper will describe the experimental technique and present results of heat transfer and flow visualisation.

Numerical Investigations of Fluid Flow and Heat Transfer Performances of Semiattached Rib Channel Design

2010 ◽  
Author(s):  
Jianhua Wang ◽  
Huichun Liu ◽  
Mao Mao ◽  
Xu Li ◽  
Zhiqiang Zhang
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Turbine Blades ◽  
Number Range ◽  
Flow And Heat Transfer ◽  
Transfer Region ◽  
Side Walls ◽  
Pass Through ◽  
Cooling Air Flow ◽  
Cooling Air

In order to enhance the convective heat transfer within cooling air flow channels, fully attached rib-designs have been widely used in the designs of turbine blades. To reduce the friction loss and the low heat transfer areas caused by the added ribs, permeable and detached ribs have been discussed. This work focuses on a novel rib-design, between the fully attached and detached ribs, which is therefore called semiattched rib here. To effectively reduce the low heat transfer region within the fully attached rib channel, two rectangular holes are excavated at the base of a straight rib at both concave corners of the bottom and side walls. The rest of the rib is attached to the base wall of the channel. A portion of coolant air can pass through the holes. To discuss the characteristics of the semiattached rib-designs, a numerical investigation has been performed by the commercial software Fluent 6.3, with the Reynolds number range from 104 to 2.5×104. The numerical results indicate that though the area-average heat transfer performances of the semiattached rib-designs are worse, the corresponding fluid flow performance are much better than both of fully attached and detached rib-designs. Another important performance is that the semiattached rib-design can fully eliminated the low heat transfer areas within the ribbed channel.

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