scholarly journals Local Heat Transfer in Turbine Disk-Cavities: Part I — Rotor and Stator Cooling With Hub Injection of Coolant

1990 ◽  
Author(s):  
R. S. Bunker ◽  
D. E. Metzger ◽  
S. Wittig
Keyword(s):  
Heat Transfer ◽  
Liquid Crystal ◽  
Mass Flow ◽  
Flow Rate ◽  
Gas Turbines ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Computer Assisted ◽  
Disk Radius ◽  
Wide Range

Results are presented from an experimental study designed to obtain detailed radial heat transfer coefficient distributions applicable to the cooling of disk-cavity regions of gas turbines. An experimental apparatus has been designed to obtain local heat transfer data on both the rotating and stationary surfaces of a parallel geometry disk-cavity system. The method employed utilizes thin thermochromic liquid crystal coatings together with video system data acquisition and computer-assisted image analysis to extract heat transfer information. The color display of the liquid crystal coatings is detected through the analysis of standard video chromanance signals. The experimental technique used is an aerodynamically steady but thermally transient one which provides consistent disk-cavity thermal boundary conditions while yet being inexpensive and highly versatile. A single circular jet is used to introduce fluid from the stator into the disk-cavity by impingement normal to the rotor surface. The present study investigates hub injection of coolant over a wide range of parameters including disk rotational Reynolds numbers of 2 to 5 · 105, rotor/stator spacing-to-disk radius ratios of .025 to .15, and jet mass flow rates between .10 and .40 times the turbulent pumped flow rate of a free disk. The results are presented as radial distributions of local Nusselt numbers. Rotor heat transfer exhibits regions of impingement and rotational domination with a transition region between, while stator heat transfer shows flow reattachment and convection regions with evidence of an inner recirculation zone. The local effects of rotation, spacing, and mass flow rate are all displayed. The significant magnitude of stator heat transfer in many cases indicates the importance of proper stator modeling to rotor and disk-cavity heat transfer results.

Local Heat Transfer in Turbine Disk Cavities: Part I—Rotor and Stator Cooling With Hub Injection of Coolant

1992 ◽  
Vol 114 (1) ◽  
pp. 211-220 ◽  
Author(s):  
R. S. Bunker ◽  
D. E. Metzger ◽  
S. Wittig
Keyword(s):  
Heat Transfer ◽  
Liquid Crystal ◽  
Mass Flow ◽  
Flow Rate ◽  
Gas Turbines ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Computer Assisted ◽  
Disk Radius ◽  
Wide Range

Results are presented from an experimental study designed to obtain detailed radial heat transfer coefficient distributions applicable to the cooling of disk-cavity regions of gas turbines. An experimental apparatus has been designed to obtain local heat transfer data on both the rotating and stationary surfaces of a parallel geometry disk-cavity system. The method employed utilizes thin thermochromic liquid crystal coatings together with video system data acquisition and computer-assisted image analysis to extract heat transfer information. The color display of the liquid crystal coatings is detected through the analysis of standard video chromanance signals. The experimental technique used is an aerodynamically steady but thermally transient one, which provides consistent disk-cavity thermal boundary conditions yet is inexpensive and highly versatile. A single circular jet is used to introduce fluid from the stator into the disk cavity by impingement normal to the rotor surface. The present study investigates hub injection of coolant over a wide range of parameters including disk rotational Reynolds numbers of 2 to 5 × 105, rotor/stator spacing-to-disk radius ratios of 0.025 to 0.15, and jet mass flow rates between 0.10 and 0.40 times the turbulent pumped flow rate of a free disk. The results are presented as radial distributions of local Nusselt numbers. Rotor heat transfer exhibits regions of impingement and rotational domination with a transition region between, while stator heat transfer shows flow reattachment and convection regions with evidence of an inner recirculation zone. The local effects of rotation, spacing, and mass flow rate are all displayed. The significant magnitude of stator heat transfer in many cases indicates the importance of proper stator modeling to rotor and disk-cavity heat transfer results.

Local Heat Transfer in Turbine Disk-Cavities: Part II — Rotor Cooling With Radial Location Injection of Coolant

1990 ◽  
Author(s):  
R. S. Bunker ◽  
D. E. Metzger ◽  
S. Wittig
Keyword(s):  
Heat Transfer ◽  
Gas Turbines ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Computer Assisted ◽  
Transfer Coefficients ◽  
Disk Radius ◽  
Radial Location ◽  
Heat Transfer Coefficients ◽  
Experimental Apparatus

Detailed radial distributions of rotor heat transfer coefficients are presented for three basic disk-cavity geometries applicable to gas turbines. The experimental apparatus has been designed to obtain local heat transfer data on a number of easily interchangeable rotor surfaces. The method employs thin thermochromic liquid crystal coatings upon the rotor surfaces together with video system data acquisition and computer-assisted image analysis to detect surface color display and to extract heat transfer information. A thermally transient, aerodynamically steady technique is used which attains consistent thermal boundary conditions over the entire disk-cavity. Cooling air is introduced into the disk-cavity via a single circular jet mounted perpendicularly into the stator at one of three radial locations; 0.4, 0.6 or 0.8 times the rotor radius. Rotor heat transfer coefficients have been obtained over a range of parameters including disk rotational Reynolds numbers of 2 to 5 · 105, rotor/stator hub spacing-to-disk radius ratios of .025 to .15, and jet mass flow rates between .10 and .40 times the turbulent pumped flow rate of a free disk. The rotor surfaces include a parallel rotor-stator system, a rotor with 5 percent diverging taper, and a similarly tapered rotor with a rim sealing lip at its extreme radius. Results are presented showing the effects of the parallel rotor, which indicate strong variations in local Nusselt numbers for all but rotational speed. These results are compared to associated hub injection data of Part I of this study, demonstrating that overall rotor heat transfer is optimized by either hub injection or radial location injection of coolant dependent upon the configuration. Results with the use of the tapered rotor show significant local Nusselt number radial variation changes over those of the parallel rotor, while the addition of a rim sealing lip appears to increase the level of the radial distribution.

Local Heat Transfer in Turbine Disk Cavities: Part II—Rotor Cooling With Radial Location Injection of Coolant

1992 ◽  
Vol 114 (1) ◽  
pp. 221-228 ◽  
Author(s):  
R. S. Bunker ◽  
D. E. Metzger ◽  
S. Wittig
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Gas Turbines ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Computer Assisted ◽  
Transfer Coefficients ◽  
Disk Radius ◽  
Radial Location ◽  
Heat Transfer Coefficients

Detailed radial distributions of rotor heat transfer coefficients are presented for three basic disk-cavity geometries applicable to gas turbines. The experimental apparatus has been designed to obtain local heat transfer data on a number of easily interchangeable rotor surfaces. The method employs thin thermochromic liquid crystal coatings upon the rotor surfaces together with video system data acquisition and computer-assisted image analysis to detect surface color display and to extract heat transfer information. A thermally transient, aerodynamically steady technique is used, which attains consistent thermal boundary conditions over the entire disk cavity. Cooling air is introduced into the disk cavity via a single circular jet mounted perpendicularly into the stator at one of the three radial locations: 0.4, 0.6, or 0.8 times the rotor radius. Rotor heat transfer coefficients have been obtained over a range of parameters including disk rotational Reynolds numbers of 2 to 5 × 105, rotor/stator hub spacing-to-disk radius ratios of 0.025 to 0.15, and jet mass flow rates between 0.10 and 0.40 times the turbulent pumped flow rate of a free disk. The rotor surfaces include a parallel rotor-stator system, a rotor with 5 percent diverging taper, and a similarly tapered rotor with a rim sealing lip at its extreme radius. Results are presented showing the effects of the parallel rotor, which indicate strong variations in local Nusselt numbers for all but rotational speed. These results are compared to associated hub injection data of Part I of this study, demonstrating that overall rotor heat transfer is optimized by either hub injection or radial location injection of coolant dependent upon the configuration. Results with the use of the tapered rotor show significant variations in local Nusselt number compared with those of the parallel rotor, while the addition of a rim sealing lip appears to increase the Nusselt number level.

Effect of Coolant Mass Flow Rate of Dirt Purge Hole on Heat Transfer and Flow Characteristics at a Turbine Blade Tip Underside

2018 ◽  
Author(s):  
Zhiqi Zhao ◽  
Lei Luo ◽  
Xun Zhou ◽  
Songtao Wang
Keyword(s):  
Heat Transfer ◽  
Mass Flow Rate ◽  
Turbine Blade ◽  
Mass Flow ◽  
Flow Rate ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Bend Channel ◽  
Blade Tip ◽  
Cooling Passage

High thermal load on the turbine blade tip surface would lead to high temperature corrosion and severe structural damage. One method to reduce blade tip high thermal stress is to use cooler fluid from the compressor, that exists dirt purge hole mounted on the tip underside, for cooling purpose. In this study, internal serpentine cooling passage is modeled as a U bend channel with a sharp 180-deg turn with the dirt purge hole arranged at the tip-wall. The effect of the layout of dirt purge hole and varying coolant mass flow rate on flow structure, heat transfer on the tip-wall and friction factor of the U bend channel are numerically studied with Reynolds number ranging from 100,000 to 440,000. The results show that the vortex pair is forced to flow near the tip-wall while the increasing shearing effect induced by the vortex pairs increases the local heat transfer. With an increase mass flow rate of the dirt purge hole, the suction effect enhances the local heat transfer performance. However, the pressure loss is also increased accordingly at all Reynolds numbers. The augmentations with Reynold analogy performance and the thermal performance for 5.8% mass flow rate case is 12.5% and 12.7%, respectively, which reaches the highest performance augmentation compared to the smooth-tip channel.

Numerical Analysis of Heat Transfer Characteristics of a Falling Film Type Plate-Fin Condenser/Reboiler

2016 ◽  
Vol 138 (8) ◽  
Author(s):  
Yuanyuan Zhou ◽  
Jianlin Yu
Keyword(s):  
Heat Transfer ◽  
Liquid Film ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Falling Film ◽  
Heat Transfer Characteristics ◽  
Allocation Ratio

Falling film type condensers/reboilers applied to cryogenic air separation units (ASUs) have drawn more attentions in recent years. This paper presents and analyzes a mathematical model for the falling film plate-fin condensers/reboilers (FPCR). In the modeling, both the laminar falling film evaporation and condensation processes, incorporating with interference of mass transfer and interfacial shear stress, are considered, and related to a plate-fin heat exchanger (PHX). The liquid film flow and heat transfer characteristics of oxygen and nitrogen fluids in the PHX are analyzed under given conditions by solving the model with a numerical iteration method. The variations of liquid film thicknesses and local heat transfer coefficients of oxygen and nitrogen as well as the total local heat transfer coefficient have been obtained. Furthermore, the effects of the inlet mass flow rate allocation ratio (i.e., the ratio of inlet mass flow rate of oxygen liquid over the base plate to that over the fin surfaces) on the wetted length of the heat transfer surfaces, the heat transfer performance, and the oxygen liquid circulation ratio (i.e., the ratio of the inlet liquid mass flow rate to the generated vapor mass flow rate) are also discussed. A proper inlet mass flow rate allocation ratio of oxygen liquid is presented. The wave effects are further considered and analyzed through the inclusion of a model for the wave factor.

A Technique for Processing Transient Heat Transfer, Liquid Crystal Experiments in the Presence of Lateral Conduction

2004 ◽  
Vol 126 (2) ◽  
pp. 247-258 ◽  
Author(s):  
John P. C. W. Ling ◽  
Peter T. Ireland ◽  
Lynne Turner
Keyword(s):  
Heat Transfer ◽  
Liquid Crystal ◽  
Film Cooling ◽  
Cooling System ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Three Dimensions ◽  
Transient Heat Transfer ◽  
Adiabatic Wall ◽  
Full Intensity

New techniques for processing transient liquid crystal heat transfer experiment have been developed. The methods are able to measure detailed local heat transfer coefficient and adiabatic wall temperature in a three temperature system from a single transient test using the full intensity history recorded. Transient liquid crystal processing methods invariably assume that lateral conduction is negligible and so the heat conduction process can be considered one-dimensional into the substrate. However, in regions with high temperature variation such as immediately downstream of a film-cooling hole, it is found that lateral conduction can become significant. For this reason, a procedure which allows for conduction in three dimensions was developed by the authors. The paper is the first report of a means of correcting data from the transient heat transfer liquid crystal experiments for the effects of significant lateral conduction. The technique was applied to a film cooling system as an example and a detailed uncertainty analysis performed.

Development of High Order LES Solver for Heat Transfer Applications Based on the Open Source OpenFOAM Framework

2015 ◽  
Author(s):  
Luca Mangani ◽  
David Roos Launchbury ◽  
Ernesto Casartelli ◽  
Giulio Romanelli
Keyword(s):  
Heat Transfer ◽  
Open Source ◽  
Gas Turbines ◽  
Incompressible Flows ◽  
Stokes Equations ◽  
Turbulence Models ◽  
Local Heat Transfer ◽  
Local Heat ◽  
High Order ◽  
Computational Time

The computation of heat transfer phenomena in gas turbines plays a key role in the continuous quest to increase performance and life of both component and machine. In order to assess different cooling approaches computational fluid dynamics (CFD) is a fundamental tool. Until now the task has often been carried out with RANS simulations, mainly due to the relatively short computational time. The clear drawback of this approach is in terms of accuracy, especially in those situations where averaged turbulence-structures are not able to capture the flow physics, thus under or overestimating the local heat transfer. The present work shows the development of a new explicit high-order incompressible solver for time-dependent flows based on the open source C++ Toolbox OpenFOAM framework. As such, the solver is enabled to compute the spatially filtered Navier-Stokes equations applied in large eddy simulations for incompressible flows. An overview of the development methods is provided, presenting numerical and algorithmic details. The solver is verified using the method of manufactured solutions, and a series of numerical experiments is performed to show third-order accuracy in time and low temporal error levels. Typical cooling devices in turbomachinery applications are then investigated, such as the flow over a turbulator geometry involving heated walls and a film cooling application. The performance of various sub-grid-scale models are tested, such as static Smagorinsky, dynamic Lagrangian, dynamic one-equation turbulence models, dynamic Smagorinsky, WALE and sigma-model. Good results were obtained in all cases with variations among the individual models.

Radiant Interchange Between Circular Disks Having Arbitrarily Different Temperatures

1961 ◽  
Vol 83 (4) ◽  
pp. 494-502 ◽  
Author(s):  
E. M. Sparrow ◽  
J. L. Gregg
Keyword(s):  
Heat Transfer ◽  
Numerical Solutions ◽  
Local Heat Transfer ◽  
Disk Surface ◽  
Radiant Heat ◽  
Local Heat ◽  
Radiant Heat Transfer ◽  
Disk Radius ◽  
Integral Equation Formulation ◽  
Different Temperatures

The problem of radiant heat transfer between parallel disks has been analyzed by generalizing the standard gray-body enclosure theory. In particular, the assumption that the radiant flux leaving a surface and the local heat flux are uniformly distributed over the surface has been lifted by an integral equation formulation. It has been shown that the general problem of disks at arbitrarily different temperatures can be conveniently broken down into two subproblems, each of which can be solved independently of the temperature level. Numerical solutions of the governing integral equations have been carried out for spacing ratios h/R (h = spacing, R = disk radius) ranging from 5.0 to 0.05 and for emissivities ranging from 0.1 to 0.9. Local heat-transfer results have been presented which, depending on spacing and emissivity, display marked variations over the disk surface. Over-all heat-transfer results have been calculated and compared with the predictions of the standard simplified enclosure theory. These predictions of the simplified theory were found to be unexpectedly good, especially in view of the large surface variations of the local heat transfer.

Three-Dimensional Transient Heat Conduction Equation Solution for Accurate Quantification of Heat Transfer Coefficient in Transient Liquid Crystal Experiments

2019 ◽  
Author(s):  
Shoaib Ahmed ◽  
Prashant Singh ◽  
Srinath V. Ekkad
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Liquid Crystal ◽  
Transfer Coefficient ◽  
Three Dimensional ◽  
Jet Impingement ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Transfer Coefficients ◽  
Conduction Model

Abstract Liquid crystal thermography and infrared thermography techniques are typically employed to measure detailed surface temperatures, where local heat transfer coefficient (HTC) values are calculated by employing suitable conduction models. One such practice, which is very popular and easy to use, is the transient liquid crystal thermography using one-dimensional semi-infinite conduction model. In these experiments, a test surface with low thermal conductivity and low thermal diffusivity (e.g. acrylic) is used where a step-change in coolant air temperature is induced and surface temperature response is recorded. An error minimization routine is then employed to guess heat transfer coefficients of each pixel, where wall temperature evolution is known through an analytical expression. The assumption that heat flow in the solid is essentially in one-dimension, often leads to errors in HTC determination and this error depends on true HTC, wall temperature evolution and HTC gradient. A representative case of array jet impingement under maximum crossflow condition has been considered here. This heat transfer enhancement concept is widely used in gas turbine leading edge and electronics cooling. Jet impingement is a popular cooling technique which results in high convective heat rates and has steep gradients in heat transfer coefficient distribution. In this paper, we have presented a procedure for solution of three-dimensional transient conduction equation using alternating direction implicit method and an error minimization routine to find accurate heat transfer coefficients at relatively lower computational cost. The HTC results obtained using 1D semi-infinite conduction model and 3D conduction model were compared and it was found that the heat transfer coefficient obtained using the 3D model was consistently higher than the conventional 1D model by 3–16%. Significant deviations, as high as 8–20% in local heat transfer at the stagnation points of the jets were observed between h1D and h3D.

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