Computational Study of Micro-Jet Impingement Heat Transfer in a High Pressure Turbine Vane

2011 ◽  
Author(s):  
Karan Anand ◽  
B. A. Jubran
Keyword(s):  
Heat Transfer ◽  
Computational Study ◽  
Jet Impingement ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Spanwise Direction ◽  
Constant Property ◽  
Impingement Heat Transfer ◽  
Turbine Vane ◽  
Volume Method

The purpose of this numerical investigation is to study the micro-jet impingement heat transfer characteristics and hydromechanics in a 3-D, actual-shaped turbine vane geometry. No concession is made on either the skewness or curvature profile of the airfoil in the streamwise direction, nor to the lean, airfoil twist or tapering of the vane in the spanwise direction. The problem on hand consists of a constant property flow of air via an array of 42 round micro jets impinging onto the inner surface of the airfoil. For simplicity, validation and better understanding of the nature of impingement heat transfer, the airfoil surfaces are provided with a constant temperature boundary condition. Validation is performed against existing numerical results on a simplified model with no spanwise tapering or twisting. The modeled volume spans a total of 12D and consists of three rows of jets; each row contains 14 inline jets. Governing equations are solved using a finite volume method in FLUENT. Effects of jet inclination (+45° and −45° inclinations) and decrease in nozzle diameter (0.51, 0.25 and 0.125 mm) are studied. Inclination of −45° produced enhanced mixing and secondary peaks with marginal decrease in stagnation values. The effect of reducing the diameter of the jets yielded positive results; the tapering effect too enhanced the local heat transfer values, which is attributed to the increase in local velocities at jet exit.

scholarly journals Numerical heat transfer analysis of micro-scale jet-impingement cooling in a high-pressure turbine vane

2021 ◽  
Author(s):  
Karan Anand
Keyword(s):  
Heat Transfer ◽  
Three Dimensional ◽  
Jet Impingement ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Heat Transfer Analysis ◽  
Transfer Rates ◽  
Numerical Heat Transfer ◽  
Turbine Vane ◽  
Single Jet

This research provides a computational analysis of heat transfer due to micro jet-impingement inside a gas turbine vane. A preliminary-parametric analysis of axisymmetric single jet was reported to better understand micro jet-impingement. In general, it was seen that as the Reynolds number increased the Nusselt number values increased. The jet to target spacing had a considerably lower impact on the heat transfer rates. Around 30% improvement was seen by reducing the diameter to half while changing the shape to an ellipse saw 20.8% improvement in Nusselt value. The numerical investigation was then followed by studying the heat transfer characteristics in a three-dimensional, actual-shaped turbine vane. Effects of jet inclination showed enhanced mixing and secondary heat transfer peaks. The effect of reducing the diameter of the jets to 0.125 mm yielded 55% heat transfer improvements compared to 0.51 mm; the tapering effect also enhanced the local heat transfer values as local velocities at jet exit increased.

The Effect of Entrainment Temperature on Jet Impingement Heat Transfer

1984 ◽  
Vol 106 (1) ◽  
pp. 27-33 ◽  
Author(s):  
S. A. Striegl ◽  
T. E. Diller
Keyword(s):  
Heat Transfer ◽  
Jet Impingement ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Recirculation Region ◽  
Measured Temperature ◽  
Air Jets ◽  
Impingement Heat Transfer ◽  
Single Jet ◽  
Multiple Plane

An experimental study was done to determine the effect of entrainment temperature on the local heat transfer rates to single and multiple, plane, turbulent impinging air jets. To determine the effect of entrainment of the surrounding fluid, the single jet issued into an environment at a temperature which was varied between the initial temperature of the jet and the temperature of the heated impingement plate. An analytical model was used to correlate the measured heat transfer rate to a single jet. The effect of the entrainment temperature in a single jet was then used to analyze the effect of entrainment from the recirculation region between the jets of a jet array. Using the measured temperature in the recirculation region to include the effect of entrainment, the single jet correlations were successfully applied to multiple jets.

Effect of Slot Jet Temperature on Impingement Heat Transfer Over a Heated Circular Cylinder

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Sharad Pachpute ◽  
B. Premachandran
Keyword(s):  
Heat Transfer ◽  
Circular Cylinder ◽  
Ambient Temperature ◽  
Stagnation Point ◽  
Nozzle Exit ◽  
Jet Impingement ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Rear Side ◽  
Impingement Heat Transfer

In this paper, heat transfer and effectiveness of a turbulent slot jet impinging over a heated circular cylinder have been investigated numerically by varying the ratio of jet temperature to the ambient temperature, Θj = Tj/Tamp, from 0.7 to 1.2. In all cases, the ambient temperature (Tamb) is assumed to be constant (300 K). The Reynolds number defined based on the average nozzle exit velocity, the diameter of the cylindrical target (D), and properties at the nozzle exit temperature, ReD=ρVD/μ is varied from 6000 to 20,000. The ratio of cylinder diameter to the slot width, D/S = 5.5, 8.5, and 17 are considered and the nondimensional distance from the nozzle exit to the cylinder, H/S is varied in the range of 2 ≤ H/S ≤ 12. The v′2¯−f turbulence model was used for numerical simulations. Numerical results reveal that the local Nusselt number is found to be higher at the stagnation point in the case of cold jet impingement at Θj = 0.7. The local heat transfer at the rear side of the cylinder is 8–18% less as compared to that of Θj = 1.0 for ReD = 6000. The local effectiveness calculated over a circular cylinder strongly depends on H/S and D/S. Based on the parametric study, a correlation has been provided for the local effectiveness at the stagnation point.

scholarly journals Computational Fluid Dynamics Analysis of Impingement Heat Transfer in an Inline Array of Multiple Jets

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Parampreet Singh ◽  
Neel Kanth Grover ◽  
Vivek Agarwal ◽  
Shubham Sharma ◽  
Jujhar Singh ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Jet Impingement ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Separation Distance ◽  
Experimental Results ◽  
Impingement Heat Transfer ◽  
Computational Fluid Dynamics Analysis ◽  
The Impact

Amid all convective heat transfer augmentation methods employing single phase, jet impingement heat transfer delivers significantly higher coefficient of local heat transfer. The arrangement leading to nine jets in square array has been used to cool a plate maintained at constant heat flux. Numerical study has been carried out using RANS-based turbulence modeling in commercial CFD Fluent software. The turbulent models used for the study are three different “k-ε” models (STD, RNG, and realizable) and SST “k-ω” model. The numerical simulation output is equated with the experimental results to find out the most accurate turbulence model. The impact of variation of Reynolds number, inter-jet spacing, and separation distance has been considered for the geometry considered. These parameters affect the coefficient of heat transfer, temperature, and turbulent kinetic energy related to flow. The local “h” values have been noticed to decline with the rise in separation distance “H/D.” The SST “k-ω” model has been noticed to be in maximum agreement with the experimental results. The average value of heat transfer coefficient “h” reduces from 210 to 193 W/m2K with increase in “H/D” from 6 to 10 at “Re” = 9000 and S/D of 3. As per numerical results, inter-jet spacing “S/D” of 3 has been determined to be the most optimum value.

scholarly journals Numerical heat transfer analysis of micro-scale jet-impingement cooling in a high-pressure turbine vane

2021 ◽  
Author(s):  
Karan Anand
Keyword(s):  
Heat Transfer ◽  
Three Dimensional ◽  
Jet Impingement ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Heat Transfer Analysis ◽  
Transfer Rates ◽  
Numerical Heat Transfer ◽  
Turbine Vane ◽  
Single Jet

This research provides a computational analysis of heat transfer due to micro jet-impingement inside a gas turbine vane. A preliminary-parametric analysis of axisymmetric single jet was reported to better understand micro jet-impingement. In general, it was seen that as the Reynolds number increased the Nusselt number values increased. The jet to target spacing had a considerably lower impact on the heat transfer rates. Around 30% improvement was seen by reducing the diameter to half while changing the shape to an ellipse saw 20.8% improvement in Nusselt value. The numerical investigation was then followed by studying the heat transfer characteristics in a three-dimensional, actual-shaped turbine vane. Effects of jet inclination showed enhanced mixing and secondary heat transfer peaks. The effect of reducing the diameter of the jets to 0.125 mm yielded 55% heat transfer improvements compared to 0.51 mm; the tapering effect also enhanced the local heat transfer values as local velocities at jet exit increased.

Entropy generation optimization for MHD natural convection of a nanofluid in porous media-filled enclosure with active parts and viscous dissipation

2017 ◽  
Vol 27 (2) ◽  
pp. 379-399 ◽  
Author(s):  
M.A. Mansour ◽  
Sameh Elsayed Ahmed ◽  
Ali J. Chamkha
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Viscous Dissipation ◽  
Entropy Generation ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Convection Flow ◽  
Negative Effects ◽  
Content Type ◽  
Volume Method

Purpose This paper aims to investigate the entropy generation due to magnetohydrodynamic natural convection flow and heat transfer in a porous enclosure filled with Cu-water nanofluid in the presence of viscous dissipation effect. The left and right walls of the cavity are thermally insulated. There are heated and cold parts, and these are placed on the bottom and top wall, respectively, whereas the remaining parts are thermally insulated. Design/methodology/approach The finite volume method is used to solve the dimensionless partial differential equations governing the problem. A comparison with previously published woks is presented and is found to be in an excellent agreement. Findings The minimization of entropy generation and local heat transfer according to different values of the governing parameters are presented in details. It is found that the presence of magnetic field has negative effects on the local entropy generation because of heat transfer and the local total entropy generation. Also, the increase in the heated part length leads to a decrease in the local Nusselt number. Originality/value This problem is original, as it has not been considered previously.

Numerical Prediction of Flow and Heat Transfer in a Parallel Plate Channel With Staggered Fins

1987 ◽  
Vol 109 (1) ◽  
pp. 25-30 ◽  
Author(s):  
K. M. Kelkar ◽  
S. V. Patankar
Keyword(s):  
Heat Transfer ◽  
Local Heat Transfer ◽  
Periodic Variation ◽  
Local Heat ◽  
Temperature Fields ◽  
Parallel Plates ◽  
Constant Property ◽  
Cross Sectional ◽  
Flow And Heat Transfer ◽  
Order Of Magnitude

Fluid flow and heat transfer in two-dimensional finned passages were analyzed for constant property laminar flow. The passage is formed by two parallel plates to which fins are attached in a staggered fashion. Both the plates are maintained at a constant temperature. Streamwise periodic variation of the cross-sectional area causes the flow and temperature fields to repeat periodically after a certain developing length. Computations were performed for different values of the Reynolds number, the Prandtl number, geometric parameters, and the fin-conductance parameter. The fins were found to cause the flow to deflect significantly and impinge upon the opposite wall so as to increase the heat transfer significantly. However, the associated increase in pressure drop was an order of magnitude higher than the increase in heat transfer. Streamline patterns and local heat transfer results are presented in addition to the overall results.

Inverse Calculation of Flame Impingement Heat Transfer

2006 ◽  
Author(s):  
Ikram Ahmed ◽  
Ildar Sabirov
Keyword(s):  
Heat Transfer ◽  
Radial Distance ◽  
Infrared Camera ◽  
Jet Impingement ◽  
Plasma Jet ◽  
Impingement Heat Transfer ◽  
Direct Measurements ◽  
Polynomial Series ◽  
Gas Flame ◽  
Volume Method

Inverse calculations are presented here for the estimation of heat transfer from an impinging flame on a flat surface. This work is a preliminary exercise for estimating heat transfer from an impinging plasma jet, where direct measurements can be very difficult and costly, and the correlations based on air or water jet impingement measurements may not be applicable because of the very high temperature (and property) gradients. As the gas flame impinges on an initially cold flat plate, the temperature evolution on the backside is recorded using an infrared camera. The time–temperature data thus obtained are then compared with those predicted by a finite volume method based code. The code uses a polynomial series for estimating the convection coefficient, which varies with radial distance. The coefficients of this polynomial are treated as a set of parameters to be estimated through the Levenberg-Marquardt approach. The results obtained so far indicate that it may be possible to use such an approach for estimating heat transfer from a plasma jet.

Effect of Film Extraction on Impingement Heat Transfer Characteristics of Jet Arrays on Spherical-Dimpled Surfaces

2015 ◽  
Author(s):  
Xing Yang ◽  
Zhao Liu ◽  
Zhenping Feng
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Film Cooling ◽  
Coupling Effect ◽  
Jet Impingement ◽  
Local Heat Transfer ◽  
Target Surface ◽  
Local Heat ◽  
Separation Distance ◽  
Plate Spacing

Detailed heat transfer distributions are numerically investigated on a multiple jet impingement target surface with staggered arrays of spherical dimples where coolant can be extracted through film holes for external film cooling. The three dimensional Reynolds-averaged Navier-Stokes analysis with SST k-ω turbulence model is conducted at jet Reynolds number from 15,000 to 35,000. The separation distance between the jet plate and the target surface varies from 3 to 5 jet diameters and two jet-induced crossflow schemes are included to be referred as large and small crossflow at one and two opposite exit openings correspondingly. Flow and heat transfer results for the dimpled target plate with three suction ratios of 2.5%, 5.0% and 12.0% are compared with those on dimpled surfaces without film holes. The results indicate the presence of film holes could alter the local heat transfer distributions, especially near the channel outlets where the crossflow level is the highest. The heat transfer enhancements by applying film holes to the dimpled surfaces is improved to different degrees at various suction ratios, and the enhancements depend on the coupling effect of impingement and channel flow, which is relevant to jet Reynolds number, jet-to-plate spacing and crossflow scheme.

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.

Sign in / Sign up

Export Citation Format

Share Document