Numerical and Experimental Investigation for Internal Cooling of Two Pass Gas Turbine Blades Channels Using Broken V Ribs

2014 ◽  
Author(s):  
Sourabh Kumar ◽  
R. S. Amano
Keyword(s):  
Gas Turbine ◽  
Thermal Stresses ◽  
Turbine Blades ◽  
Research Work ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Inlet Temperature ◽  
Internal Cooling ◽  
Cooling Channel ◽  
Square Duct

Improvements in the thermal efficiency of a gas turbine can be obtained by operating it at high inlet temperatures. This high inlet temperature develops high thermal stresses on the turbine blades in addition to improving the performance. Cooling methodologies are implemented inside the blades to withstand those high temperatures. Four different combinations of broken 60° V ribs in cooling channel are considered. The research work investigates and compares numerically and experimentally, internal cooling of channels with broken V ribs. Local heat transfer in a square duct roughened with 60° V broken ribs is investigated for three different Reynolds numbers. Aspect ratio of the channel is taken to be 1:1. The pitch of the rib is considered to be 10 times the width of the rib, which is 0.0635 m. The square cross section of the channel is 0.508 × 0.508 m2 with 0.6096 m length. This study provides information about the best configuration of a broken V rib in a cooling channel.

Numerical Simulation of Two Pass Gas Turbine Blade Internal Cooling Channels With 90 Degree Varying Height Ribs

2012 ◽  
Author(s):  
Sourabh Kumar ◽  
R. S. Amano
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Gas Turbine ◽  
Thermal Stresses ◽  
Turbine Blades ◽  
Simulation Software ◽  
Inlet Temperature ◽  
Internal Cooling ◽  
Ribbed Channel ◽  
Smooth Channel

Improvement in thermal efficiency of gas turbine can be obtained by operating it at high inlet temperatures. In addition to improving the performance, the cons of high inlet temperature is high thermal stresses on the turbine blades. To improve life and performance of the blade, improved cooling technologies are desired. The main objective of this paper is to perform computational analysis of the ribs with varying height and compare this with 90 degree ribbed channel and smooth channels. The numerical analysis is carried out using ANSYS-Fluent, a flow modeling simulation software. The flow is assumed to be steady state and flow turbulence is modeled using the k-ε with Standard Wall Functions. Local heat transfer and friction loss in a square duct roughened with 90 degree ribs with varying height is investigated for different Reynolds number. The pitch of the rib is considered to be 10 times the height of rib which is 0.0635 m. The square cross section of the channel is .0508x .0508 m2. The pitch of rib to rib height ratio varies from 10 to 20 at the center of the channel. There is a rib considered at the turn section as well. The numerical simulation produced higher heat transfer for the varying height ribs as compared to 90 degree ribbed channel and smooth channel.

scholarly journals Oscillator Fin as a Novel Heat Transfer Augmentation Device for Gas Turbine Cooling Applications

1998 ◽  
Author(s):  
Oguz Uzol ◽  
Cengiz Camci
Keyword(s):  
Heat Transfer ◽  
Kinetic Energy ◽  
Gas Turbine ◽  
Turbulent Kinetic Energy ◽  
Stokes Equations ◽  
Turbine Blades ◽  
Local Heat Transfer ◽  
Internal Cooling ◽  
Pin Fin ◽  
Heat Transfer Augmentation

A new concept for enhanced turbulent transport of heat in internal coolant passages of gas turbine blades is introduced. The new heat transfer augmentation component called “oscillator fin” is based on an unsteady flow system using the interaction of multiple unsteady jets and wakes generated downstream of a fluidic oscillator. Incompressible, unsteady and two dimensional solutions of Reynolds Averaged Navier-Stokes equations are obtained both for an oscillator fin and for an equivalent cylindrical pin fin and the results are compared. Preliminary results show that a significant increase in the turbulent kinetic energy level occur in the wake region of the oscillator fin with respect to the cylinder with similar level of aerodynamic penalty. The new concept does not require additional components or power to sustain its oscillations and its manufacturing is as easy as a conventional pin fin. The present study makes use of an unsteady numerical simulation of mass, momentum, turbulent kinetic energy and dissipation rate conservation equations for flow visualization downstream of the new oscillator fin and an equivalent cylinder. Relative enhancements of turbulent kinetic energy and comparisons of the total pressure field from transient simulations qualitatively suggest that the oscillator fin has excellent potential in enhancing local heat transfer in internal cooling passages without significant aerodynamic penalty.

scholarly journals Effect of Discrete Ribs on Heat Transfer and Friction Inside Narrow Rectangular Cross Section Cooling Passage of Gas Turbine Blade

2021 ◽  
Vol 10 (6) ◽  
pp. 192-209
Author(s):  
Karthik Krishnaswamy ◽  
◽  
Srikanth Salyan ◽  
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Turbine Blades ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Hydraulic Diameter ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Cooling Passage

The performance of a gas turbine during the service life can be enhanced by cooling the turbine blades efficiently. The objective of this study is to achieve high thermohydraulic performance (THP) inside a cooling passage of a turbine blade having aspect ratio (AR) 1:5 by using discrete W and V-shaped ribs. Hydraulic diameter (Dh) of the cooling passage is 50 mm. Ribs are positioned facing downstream with angle-of-attack (α) of 30° and 45° for discrete W-ribs and discerte V-ribs respectively. The rib profiles with rib height to hydraulic diameter ratio (e/Dh) or blockage ratio 0.06 and pitch (P) 36 mm are tested for Reynolds number (Re) range 30000-75000. Analysis reveals that, area averaged Nusselt numbers of the rib profiles are comparable, with maximum difference of 6% at Re 30000, which is within the limits of uncertainty. Variation of local heat transfer coefficients along the stream exhibited a saw tooth profile, with discrete W-ribs exhibiting higher variations. Along spanwise direction, discrete V-ribs showed larger variations. Maximum variation in local heat transfer coefficients is estimated to be 25%. For experimented Re range, friction loss for discrete W-ribs is higher than discrete-V ribs. Rib profiles exhibited superior heat transfer capabilities. The best Nu/Nuo achieved for discrete Vribs is 3.4 and discrete W-ribs is 3.6. In view of superior heat transfer capabilities, ribs can be deployed in cooling passages near the leading edge, where the temperatures are very high. The best THPo achieved is 3.2 for discrete V-ribs and 3 for discrete W-ribs at Re 30000. The ribs can also enhance the power-toweight ratio as they can produce high thermohydraulic performances for low blockage ratios.

Topology Optimization of Serpentine Channels for Minimization of Pressure Loss and Maximization of Heat Transfer Performance As Applied for Additive Manufacturing

2019 ◽  
Author(s):  
Shinjan Ghosh ◽  
Jayanta S. Kapat
Keyword(s):  
Heat Transfer ◽  
Topology Optimization ◽  
Additive Manufacturing ◽  
Pressure Drop ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Inlet Temperature ◽  
Internal Cooling ◽  
Cooling Channels ◽  
Blade Cooling

Abstract Gas Turbine blade cooling is an important topic of research, as a high turbine inlet temperature (TIT) essentially means an increase in efficiency of gas turbine cycles. Internal cooling channels in gas turbine blades are key to the cooling and prevention of thermal failure of the material. Serpentine channels are a common feature in internal blade cooling. Optimization methods are often employed in the design of blade internal cooling channels to improve heat-transfer and reduce pressure drop. Topology optimization uses a variable porosity approach to manipulate flow geometries by adding or removing material. Such a method has been employed in the current work to modify the geometric configuration of a serpentine channel to improve total heat transferred and reduce the pressure drop. An in-house OpenFOAM solver has been used to create non-traditional geometries from two generic designs. Geometry-1 is a 2-D serpentine passage with an inlet and 4 bleeding holes as outlets for ejection into the trailing edge. Geometry-2 is a 3-D serpentine passage with an aspect ratio of 3:1 and consists of two 180-degree bends. The inlet velocity for both the geometries was used as 20 m/s. The governing equations employ a “Brinkman porosity parameter” to account for the porous cells in the flow domain. Results have shown a change in shape of the channel walls to enhance heat-transfer in the passage. Additive manufacturing can be employed to make such unconventional shapes.

The Effects of an Excited Impinging Jet on the Local Heat Transfer Coefficient of Aircraft Turbine Blades

1988 ◽  
Author(s):  
P. J. Disimile ◽  
D. M. Paule
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Turbine Blade ◽  
Turbine Blades ◽  
Leading Edge ◽  
Local Heat Transfer ◽  
Impinging Jet ◽  
Local Heat ◽  
Primary Objective ◽  
Inlet Temperature

The primary objective of this paper is to present the results of research into the effects of periodic excitation upon the local heat transfer characteristics of a turbine blade cooled by an impinging jet of air. A curved plate (used to simulate the inner leading edge of a turbine blade) was subjected to a two-dimensional jet flow field (Re = 10,000) with a superimposed periodic acoustic disturbance. When compared to the naturally disturbed flow, the excited flow field was found to reduce the local Nusselt number and cool the blade less efficiently (by as much as ten percent in the extreme cases). The results of the study appear to indicate that harmonic disturbances present a serious controlling factor in the quest for optimization of turbine blade cooling techniques. By isolating dominant frequencies in gas turbine engines and working to suppress them, the authors believe it possible to make significant contributions towards the desired increase in turbine inlet temperature.

Numerical Study on Local Heat Transfer in a Rotating Cooling Channel

2018 ◽  
Author(s):  
Min Ren ◽  
Xueying Li ◽  
Jing Ren ◽  
Hongde Jiang
Keyword(s):  
Heat Transfer ◽  
Rotation Number ◽  
Numerical Study ◽  
Density Ratio ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Hydraulic Diameter ◽  
Internal Cooling ◽  
Cooling Channel ◽  
Channel Diameter

Effect of rotation on turbine blade internal cooling is an important factor in gas turbine cooling systems. To obtain the distribution of the heat transfer and the flow field in a rotating cooling channel, a series of computational simulations using the realizable k-ε model are utilized. The channel Reynolds number based on the channel diameter is 25000. The rotation number ranges from 0 to 0.20. The investigated density ratio Δρ/ρ ranges from 0.05 to 0.33 and the range of radius-to-passage hydraulic diameter r/D is from 10 to 40. The results show that the heat transfer on the trailing side shows an overall augmentation while that on the leading side decreases in the cooling channel. When the channel is stationary, the density ratio has little effect on the thermal performance. And for the rotating channel, the heat transfer on the trailing side and leading side both increases when the density ratio increases. The heat transfer both on the trailing side and leading side decreases when the radius-to-passage hydraulic diameter (r/D) increase. And the radius has a greater effect when the rotation number is higher.

scholarly journals Heat Transfer Predictions for Rotating U-Shaped Coolant Channels With Skewed Ribs and With Smooth Walls

1997 ◽  
Author(s):  
Bernhard Bonhoff ◽  
Uwe Tomm ◽  
Bruce V. Johnson ◽  
Ian Jennions
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Computational Study ◽  
Flow Direction ◽  
Turbine Blades ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Secondary Flows ◽  
Internal Cooling ◽  
Flow Conditions

A computational study was performed for the flow and heat transfer in rotating coolant passages with two legs connected with a U-bend. The dimensionless flow conditions and the rotational speed were typical of those in the internal cooling passages of turbine blades. The calculations were performed for two geometries and flow conditions for which experimental heat transfer data were obtained under the NASA HOST project. The first model had smooth surfaces on all walls. The second model had opposing ribs staggered and angled at 45 deg. to the main flow direction on two walls of the legs, corresponding to the coolant passage surfaces adjacent to the pressure and suction surfaces of a turbine airfoil. Results from these calculations were compared with the previous measurements as well as with previous calculations for the nonrotating models at a Reynolds number of 25,000 and a rotation number of 0.24. At these conditions, the predicted heat transfer is known to be strongly influenced by the turbulence and wall models. The differential Reynolds-stress model (RSM) was used for the calculation. Local heat transfer results are presented as well as results averaged over wall segments. The averaged heat transfer predictions were close to the experimental results in the first leg of the channel, while the heat transfer in the second leg was overestimated by RSM. The flow field results showed a large amount of secondary flow in the channels with rotational velocities as large as 90 percent of the mean value. These secondary flows were attributed to the buoyancy effects, the Coriolis forces, the curvature of the bend and the orientation of the skewed ribs. Details of the flow field are discussed. Both the magnitude and the change of the heat transfer were captured well with the calculations for the rotating cases.

Effects of Boot-Shaped Rib On Heat Transfer Characteristics of Internal Cooling Turbine Blades

2020 ◽  
Author(s):  
Ky-Quang Pham ◽  
Quang-Hai Nguyen ◽  
Tai-Duy Vu ◽  
Cong-Truong Dinh
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Cooling System ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Wall Friction ◽  
Inlet Temperature ◽  
Internal Cooling ◽  
Toe Angle

Abstract Gas turbine engine has been widely applied to many heavy industries, such as marine propulsion and aerospace fields. Increasing turbine inlet temperature is one of the major ways to improve the thermal efficiency of gas turbines. Internal cooling for gas turbine cooling system is one of the most commonly used approaches to reduce the temperature of blades by casting various kinds of ribs in serpentine passages to enhance the heat transfer between the coolant and hot surface of gas turbine blades. This paper presents an investigation of boot-shaped rib design to increase the heat transfer performances in the internal cooling turbine blades for gas turbine engines. By varying the design parameter configuration, the airflow is taken with higher momentum, and the minor vortex being at the front rib is relatively removed. The object of this investigation is increasing the reattachment airflow to wall and reducing the vortex occurring near the rib for improving the performances of heat transfer using three-dimensional Reynolds-averaged Navier-Stokes with the SST model. A parametric study of the boot-shaped rib design was performed using various geometric parameters related to the heel-angle, toe-angle, slope-height and rib-width to find their effect on the Nusselt number, temperature on the ribbed wall, friction factor ratio of the channel and thermal performance factor. The numerical results showed that the heat transfer performances are significantly increased with the heel-angle, toe-angle, slope-height, while that remained relatively constant with the rib-width.

CFD Analysis and Experimental Validation of the Flow Field in a Rib Roughed Turbine Internal Cooling Channel

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Yasin Sohret ◽  
T. Hikmet Karakoc
Keyword(s):  
Flow Field ◽  
Gas Turbine ◽  
Turbine Engines ◽  
Inlet Temperature ◽  
Internal Cooling ◽  
Gas Turbine Engines ◽  
Cooling Channel ◽  
Turbine Inlet Temperature ◽  
Computational Fluid Dynamics Analysis

Abstract Advances in thermal science force us to develop more efficient systems. The efficiency of widely-used gas turbine engines, is highly dependent on turbine inlet temperature. However, a high turbine inlet temperature yields material deterioration and long term degradation of turbines. To prevent material deterioration, cooling the hot zones of gas turbine engines, particularly turbine components and blades, is a priority. In this way, long term degradation of the turbine is prevented, while the thermal efficiency of the gas turbine engine is boosted. In the current paper, a flow field within a rib roughed blade internal cooling channel is discussed. Within this scope, a computational fluid dynamics analysis is conducted using a Standard k-ω turbulence model. After this, the same case is experimentally investigated. Experimental results obtained from particle image velocimetry measurements are used to validate the results of the computational fluid dynamics analysis. At the end of the study, the flow field is fully mapped with the recirculation and separation zones being clearly pinpointed.

scholarly journals Conjugated heat transfer analysis of gas turbine vanes using MacCormack's technique

2008 ◽  
Vol 12 (3) ◽  
pp. 65-73 ◽  
Author(s):  
Micha Kumar ◽  
N. Alagumurthi ◽  
K. Palaniradja
Keyword(s):  
Gas Turbine ◽  
High Performance ◽  
Turbine Blades ◽  
Heat Transfer Analysis ◽  
Inlet Temperature ◽  
Internal Cooling ◽  
Gas Temperature ◽  
Turbine Engine ◽  
Material Development ◽  
Turbine Vanes

It is well known that turbine engine efficiency can be improved by increasing the turbine inlet gas temperature. This causes an increase of heat load to the turbine components. Current inlet temperature level in advanced gas turbine is far above the melting point of the vane material. Therefore, along with high temperature material development, sophisticated cooling scheme must be developed for continuous safe operation of gas turbine with high performance. Gas turbine blades are cooled internally and externally. Internal cooling is achieved by passing the coolant through passages inside the blade and extracting the heat from outside of the blade. This paper focuses on turbine vanes internal cooling. The effect of arrangement of rib and parabolic fin turbulator in the internal cooling channel and numerical investigation of temperature distribution along the vane material has been presented. The formulations for the internal cooling for the turbine vane have been done and these formulated equations are solved by MacCormack's technique.

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