scholarly journals Heat Transfer Over Non-Porous and Porous Smooth End Wall of a Linear Guide Vane in the Presence of Freestream Turbulence

1999 ◽  
Author(s):  
Artem A. Khalatov ◽  
Sergey V. Shevtsov ◽  
Nick Syred
Keyword(s):  
Heat Transfer ◽  
Boundary Conditions ◽  
Gas Turbine ◽  
Guide Vane ◽  
Three Dimensional ◽  
Axial Component ◽  
Wall Heat Transfer ◽  
Freestream Turbulence ◽  
Turbine Guide Vane ◽  
End Wall

The end wall of a gas turbine guide vane is one of turbine components where cooling is extremely complex due to a three-dimensional fluid flow and heat transfer nature. Most existing end wall heat transfer data were obtained over a non-porous surface with no effect of freestream turbulence. In real situations the typical turbulence level in front of a guide vane varies widely and reaches 25–30 % in some modern gas turbine engines. No doubt, this factor should be taken into account in the design of end wall cooling systems. New experimental results are presented in this paper describing the effect of freestream turbulence on local heat transfer over non-porous and porous smooth end walls of the same configuration. A linear scaled-up model of a real gas turbine guide vane was employed in the experimental programme. Decay of the axial freestream turbulence in a space between adjacent blades was measured and two simplified versions of the experimental correction functions describing the effect of freestream turbulence on local end wall heat transfer were obtained. The derived correction functions include the axial component of freestream turbulence and should be envisaged as a first attempt to define quantitatively the effect of freestream turbulence over an end wall in different conditions. It was found that both correction functions are virtually identical and agree satisfactorily with the published experimental data, reflecting the effect of freestream turbulence over a flat plate. It confirms the approximately common character of freestream turbulence influence for different boundary conditions. It was concluded that further experimental studies of three-dimensional turbulent structure over an end wall for various boundary conditions are required to develop more exact correlations.

Measurement and Calculation of End Wall Heat Transfer and Aerodynamics on a Nozzle Guide Vane in Annular Cascade

1990 ◽  
Author(s):  
N. W. Harvey ◽  
T. V. Jones
Keyword(s):  
Heat Transfer ◽  
Guide Vane ◽  
Three Dimensional ◽  
Surface Flow ◽  
Wall Heat Transfer ◽  
Transfer Rates ◽  
Nozzle Guide Vane ◽  
Nozzle Guide ◽  
Annular Cascade ◽  
End Wall

Detailed measurements of surface static pressures and heat transfer rates on the aerofoil and hub end wall of an annular nozzle guide vane (in the absence of a downstream rotor) are presented. Heat transfer rates have been measured using thin film gauges in an annular cascade in the Pyestock Isentropic Light Piston Cascade. Test Mach numbers, Reynolds numbers and cascade geometry are fully representative of engine conditions. The results of 3-D calculations of surface Mach number and 2-D calculations of aerofoil heat transfer are presented and compared with the measurements. A new method of calculating end wall heat transfer using the axisymmetric analogue for three-dimensional boundary layers is described in detail. The method uses a 3-D Euler solver to calculate the inviscid surface streamlines along which heat transfer coefficients are calculated. The metric coefficient which describes the lateral convergence or divergence of the streamlines is used to include three-dimensional effects in the calculation. The calculated heat transfer rates compare well with the measured values. Reference is made to surface flow visualization in the interpretation of the results.

Application of RANS and LES to the Prediction of Flows in High Pressure Turbine Components

2011 ◽  
Author(s):  
Nicolas Gourdain ◽  
Laurent Y. M. Gicquel ◽  
Remy Fransen ◽  
Elena Collado ◽  
Tony Arts
Keyword(s):  
Heat Transfer ◽  
Vortex Shedding ◽  
Guide Vane ◽  
Unsteady Flows ◽  
Separated Flow ◽  
Heat Fluxes ◽  
Boundary Layer Transition ◽  
Wall Heat Transfer ◽  
Layer Transition ◽  
Turbine Guide Vane

This paper investigates the capability of numerical simulations to estimate unsteady flows and wall heat fluxes in turbine components with both structured and unstructured flow solvers. Different numerical approaches are assessed, from steady-state methods based on the Reynolds Averaged Navier-Stokes (RANS) equations to more sophisticated methods such as the Large Eddy Simulation (LES) technique. Three test cases are investigated: the vortex shedding induced by a turbine guide vane, the wall heat transfer in another turbine guide vane and a separated flow phenomenon in an internal turbine cooling channel. Steady flow simulations usually fail to predict the mean effects of unsteady flows (such as vortex shedding) and wall heat transfer, mainly because laminar-to turbulent transition and the inlet turbulent intensity are not correctly taken into account. Actually, only the LES (partially) succeeds to accurately estimate unsteady flows and wall heat fluxes in complex configurations. The results presented in this paper indicate that this method considerably improves the level of physical description (including boundary layer transition). However, the LES still requires developments and validations for such complex flows. This study also points out the dependency of results to parameters such as the freestream turbulence intensity. When feasible solutions obtained with both structured and unstructured flow solvers are compared to experimental data.

Effects of inlet turbulence intensity on wall heat transfer in a turbine guide vane

2020 ◽  
Vol 34 (14n16) ◽  
pp. 2040082
Author(s):  
Ke-Qi Hu ◽  
Yi-Fan Xia ◽  
Yao Zheng ◽  
Gao-Feng Wang
Keyword(s):  
Heat Transfer ◽  
Turbulence Intensity ◽  
Gas Turbines ◽  
Guide Vane ◽  
Turbulence Models ◽  
Suction Side ◽  
Industrial Applications ◽  
Wall Heat Transfer ◽  
Turbine Guide Vane ◽  
Sas Model

Heat transfer is an important phenomenon that exists in many industrial applications, especially for gas turbines, aeronautical engines. In this work, two different turbulence models ([Formula: see text] and SAS model) are used to investigate the effects of inlet turbulence on wall heat transfer and the characteristics of flow field in a well-known turbine guide vane (LS89). In order to handle the transition, Menter’s [Formula: see text] transition model is used. The simulations show that the inlet turbulence has an apparent effect on the wall heat transfer of the vane. Not only the maximum wall heat transfer coefficient is increased, the distribution of wall heat flux at the suction side is also modified. The isentropic Mach number along the vane surface is insensitive to the variance of inlet turbulence intensity. Besides, a shock appears in the throat and a laminar-to-turbulence transition position moves forward after the main flow turbulence is enhanced. Moreover, the results indicate that SAS model is capable of capturing more flow structures such as reflecting pressure waves and shedding vortexes while the [Formula: see text] model misses them due to the dissipation.

Effect of Secondary Flow on Heat Transfer Over a Guide Vane Suction Side

2002 ◽  
Author(s):  
Artem Khalatov ◽  
Nick Syred ◽  
Sergei Khalatov ◽  
Philip Bowen
Keyword(s):  
Heat Transfer ◽  
Secondary Flow ◽  
Gas Turbine ◽  
Guide Vane ◽  
Flow Temperature ◽  
Flow Measurements ◽  
Local Flow ◽  
Experimental Data Processing ◽  
Average Flow ◽  
End Wall

An accurate design of a guide vane has become a major issue in gas turbine engineering since secondary flow in vane cascade has a significant effect on the end wall and airfoil suction surfaces. Heat transfer and average flow measurements were performed in a linear guide vane cascade consisting of five gas turbine vanes. All measurements were taken on the suction surface of the middle (third) airfoil. The height-to-pitch ratio H/S was varied from 1.0 to 0.17, the inlet boundary layer thickness δin was either 2 mm or 10 mm. The vortex structures influence the average flow parameters, the laminar-to-turbulence transition, and the local heat transfer. This is especially pronounced in the area close to the end wall area. The inlet flow temperature non-uniformity has no influence on the heat transfer, however local flow temperature ‘spikes’ were registered at x = 0.6 due to the flow enthalpy migration in the span-wise direction. A few useful correlations are suggested as a result of the experimental data processing.

Effect of Simulated Combustor Temperature Nonuniformity on HP Vane and End Wall Heat Transfer: An Experimental and Computational Investigation

2010 ◽  
Vol 133 (3) ◽  
Author(s):  
Imran Qureshi ◽  
Arrigo Beretta ◽  
Thomas Povey
Keyword(s):  
Heat Transfer ◽  
Guide Vane ◽  
Test Facility ◽  
Inlet Temperature ◽  
Wall Heat Transfer ◽  
Computational Fluid Dynamics Cfd ◽  
Inlet Conditions ◽  
Nozzle Guide ◽  
End Wall ◽  
Computational Predictions

This paper presents experimental measurements and computational predictions of surface and end wall heat transfer for a high-pressure (HP) nozzle guide vane operating as part of a full HP turbine stage in an annular rotating turbine facility, with and without inlet temperature distortion (hot streaks). A detailed aerodynamic survey of the vane surface is also presented. The test turbine was the unshrouded MT1 turbine, installed in the Turbine Test Facility (previously called Isentropic Light Piston Facility) at QinetiQ, Farnborough, UK. This is a short-duration facility, which simulates engine-representative M, Re, nondimensional speed, and gas-to-wall temperature ratio at the turbine inlet. The facility has recently been upgraded to incorporate an advanced second-generation combustor simulator, capable of simulating well-defined, aggressive temperature profiles in both the radial and circumferential directions. This work forms part of the pan-European research program, TATEF II. Measurements of HP vane and end wall heat transfer obtained with inlet temperature distortion are compared with results for uniform inlet conditions. Steady and unsteady computational fluid dynamics (CFD) predictions have also been conducted on vane and end wall surfaces using the Rolls-Royce CFD code HYDRA to complement the analysis of experimental results. The heat transfer measurements presented in this paper are the first of their kind in that the temperature distortion is representative of an extreme cycle point, and was simulated with good periodicity and with well-defined boundary conditions in the test turbine.

Numerical Simulation of Gas Flow and Heat Transfer in Cross-Wavy Primary Surface Channel for Microtubine Recuperators

2005 ◽  
Author(s):  
H. X. Liang ◽  
Q. W. Wang ◽  
L. Q. Luo ◽  
Z. P. Feng
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Gas Turbine ◽  
Numerical Study ◽  
High Reliability ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Flow And Heat Transfer ◽  
High Heat Transfer ◽  
The Cross

Three-dimensional numerical simulation was conducted to investigate the flow field and heat transfer performance of the Cross-Wavy Primary Surface (CWPS) recuperators for microturbines. Using high-effective compact recuperators to achieve high thermal efficiency is one of the key techniques in the development of microturbine in recent years. Recuperators need to have minimum volume and weight, high reliability and durability. Most important of all, they need to have high thermal-effectiveness and low pressure-losses so that the gas turbine system can achieve high thermal performances. These requirements have attracted some research efforts in designing and implementing low-cost and compact recuperators for gas turbine engines recently. One of the promising techniques to achieve this goal is the so-called primary surface channels with small hydraulic dimensions. In this paper, we conducted a three-dimensional numerical study of flow and heat transfer for the Cross-Wavy Primary Surface (CWPS) channels with two different geometries. In the CWPS configurations the secondary flow is created by means of curved and interrupted surfaces, which may disturb the thermal boundary layers and thus improve the thermal performances of the channels. To facilitate comparison, we chose the identical hydraulic diameters for the above four CWPS channels. Since our experiments on real recuperators showed that the Reynolds number ranges from 150 to 500 under the operating conditions, we implemented all the simulations under laminar flow situations. By analyzing the correlations of Nusselt numbers and friction factors vs. Reynolds numbers of the four CWPS channels, we found that the CWPS channels have superior and comprehensive thermal performance with high compactness, i.e., high heat transfer area to volume ratio, indicating excellent commercialized application in the compact recuperators.

Experimental Studies of Leading Edge Contouring Influence on Secondary Losses in Transonic Turbines

2012 ◽  
Author(s):  
Ranjan Saha ◽  
Jens Fridh ◽  
Torsten Fransson ◽  
Boris I. Mamaev ◽  
Mats Annerfeldt
Keyword(s):  
Gas Turbine ◽  
Guide Vane ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Leading Edge ◽  
Secondary Flows ◽  
Noticeable Effect ◽  
Flow Angle ◽  
Wide Range ◽  
Contour Plots

An experimental study of the hub leading edge contouring using fillets is performed in an annular sector cascade to observe the influence of secondary flows and aerodynamic losses. The investigated vane is a three dimensional gas turbine guide vane (geometrically similar) with a mid-span aspect ratio of 0.46. The measurements are carried out on the leading edge fillet and baseline cases using pneumatic probes. Significant precautions have been taken to increase the accuracy of the measurements. The investigations are performed for a wide range of operating exit Mach numbers from 0.5 to 0.9 at a design inlet flow angle of 90°. Data presented include the loading, fields of total pressures, exit flow angles, radial flow angles, as well as profile and secondary losses. The vane has a small profile loss of approximately 2.5% and secondary loss of about 1.1%. Contour plots of vorticity distributions and velocity vectors indicate there is a small influence of the vortex-structure in endwall regions when the leading edge fillet is used. Compared to the baseline case the loss for the filleted case is lower up to 13% of span and higher from 13% to 20% of the span for a reference condition with Mach no. of 0.9. For the filleted case, there is a small increase of turning up to 15% of the span and then a small decrease up to 35% of the span. Hence, there are no significant influences on the losses and turning for the filleted case. Results lead to the conclusion that one cannot expect a noticeable effect of leading edge contouring on the aerodynamic efficiency for the investigated 1st stage vane of a modern gas turbine.

Conjugate Heat Transfer Analysis of a High Pressure Air-Cooled Gas Turbine Vane

2010 ◽  
Author(s):  
Zhenfeng Wang ◽  
Peigang Yan ◽  
Hongyan Huang ◽  
Wanjin Han
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Boundary Conditions ◽  
Gas Turbine ◽  
Turbulence Model ◽  
Conjugate Heat Transfer ◽  
Suction Side ◽  
Turbulence Characteristic ◽  
Transition Flow ◽  
Characteristic Boundary

The ANSYS-CFX software is used to simulate NASA-Mark II high pressure air-cooled gas turbine. The work condition is Run 5411 which have transition flow characteristics. The different turbulence models are adopted to solve conjugate heat transfer problem of this three-dimensional turbine blade. Comparing to the experimental results, k-ω-SST-γ-θ turbulence model results are more accurate and can simulate accurately the flow and heat transfer characteristics of turbine with transition flow characteristics. But k-ω-SST-γ-θ turbulence model overestimates the turbulence kinetic energy of blade local region and makes the heat transfer coefficient higher. It causes that local region temperature of suction side is higher. In this paper, the compiled code adopts the B-L algebra model and simulates the same computation model. The results show that the results of B-L model are accurate besides it has 4% temperature error in the suction side transition region. In addition, different turbulence characteristic boundary conditions of turbine inner-cooling passages are given and K-ω-SST-γ-θ turbulence model is adopted in order to obtain the effect of turbulence characteristic boundary conditions for the conjugate heat transfer computation results. The results show that the turbulence characteristic boundary conditions of turbine inner-cooling passages have a great effect on the conjugate heat transfer results of high pressure gas turbine. ANSYS is applied to analysis the thermal stress of Mark II blade which has ten radial cooled passages and the results of Von Mises stress show that the temperature gradient results have a great effect on the results of blade thermal stress.

The Influence of Endwall Contouring on the Performance of a Turbine Nozzle Guide Vane

1998 ◽  
Author(s):  
Vincenzo Dossena ◽  
Antonio Perdichizzi ◽  
Marco Savini
Keyword(s):  
Flow Field ◽  
Gas Turbine ◽  
Guide Vane ◽  
Three Dimensional ◽  
Angle Distribution ◽  
Secondary Effects ◽  
Three Dimensional Flow ◽  
Nozzle Height ◽  
Dimensional Flow ◽  
Endwall Contouring

The paper presents the results of a detailed investigation of the flow field in a gas turbine linear cascade. A comparison between a contoured and a planar configuration of the same cascade has been performed, and differences in the three-dimensional flow field are here analyzed and discussed. The flow evolution downstream of the trailing edge was surveyed by means of probe traversing while a 3-D Navier-Stokes solver was employed to obtain information on flow structures inside the vaned passages. The experimental measurements and the numerical simulation of the three-dimensional flow field has been performed for two cascades; one with planar endwalls, and the other with one planar and one profiled endwall, so as to present a reduction of the nozzle height. The investigation was carried out at an isentropic downstream Mach number of 0.6. Airfoils of both cascades were scaled from the same high pressure gas turbine inlet guide vane. Measurements of the three-dimensional flow field have been performed on five planes downstream of the cascades by means of a miniaturized five-hole pressure probe. The presence of endwall contouring strongly influences the secondary effects; the vortex generation and their development is inhibited by the stronger acceleration taking place throughout the cascade. The results show that the secondary effects on the contoured side of the passage are confined in the endwall region, while on the flat side the secondary vortices display characteristics similar to the ones occurring downstream of the planar cascade. The spanwise outlet angle distribution presents a linear variation for most of the nozzle height, with quite low values approaching the contoured endwall. The analysis of mass averaged losses shows a significant performance improvement in the contoured cascade. This has to be ascribed not only to lower secondary losses but also to a reduction of the profile losses.

Microprocessor Silicon Die Temperature Prediction by Simplified Boundary Conditions

2015 ◽  
Author(s):  
Koji Nishi ◽  
Tomoyuki Hatakeyama ◽  
Shinji Nakagawa ◽  
Masaru Ishizuka
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Boundary Conditions ◽  
Thermal Resistance ◽  
Hot Spot ◽  
Three Dimensional ◽  
Thermal Design ◽  
Target Temperature ◽  
One Dimensional ◽  
Thermal Network

The thermal network method has a long history with thermal design of electronic equipment. In particular, a one-dimensional thermal network is useful to know the temperature and heat transfer rate along each heat transfer path. It also saves computation time and/or computation resources to obtain target temperature. However, unlike three-dimensional thermal simulation with fine pitch grids and a three-dimensional thermal network with sufficient numbers of nodes, a traditional one-dimensional thermal network cannot predict the temperature of a microprocessor silicon die hot spot with sufficient accuracy in a three-dimensional domain analysis. Therefore, this paper introduces a one-dimensional thermal network with average temperature nodes. Thermal resistance values need to be obtained to calculate target temperature in a thermal network. For this purpose, thermal resistance calculation methodology with simplified boundary conditions, which calculates thermal resistance values from an analytical solution, is also introduced in this paper. The effectiveness of the methodology is explored with a simple model of the microprocessor system. The calculated result by the methodology is compared to a three-dimensional heat conduction simulation result. It is found that the introduced technique matches the three-dimensional heat conduction simulation result well.

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