Three Dimensional Measurements of Instantaneous Flow Field in Corners With Smooth Surfaces Under a Zero Pressure Gradient

2004 ◽  
Author(s):  
Michael Phillips ◽  
Steve Deutsch ◽  
Arnie Fontaine ◽  
Savas Yavuzkurt
Keyword(s):  
Heat Transfer ◽  
Pressure Gradient ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Instantaneous Velocity ◽  
Stream Velocity ◽  
Internal Cooling ◽  
Mean Velocity ◽  
Data Set ◽  
Corner Flow

Three dimensional instantaneous velocity data were taken in a turbulent corner flow with smooth walls under a zero pressure gradient. Experiments were carried out in air with a free stream velocity of 13 m/s and an axial Reynolds number of about 10,000,000. The data were collected using a three-component LDV system that was configured in a nearly orthogonal setup. Measurements were made down to a y+ of approximately 5, and should provide a valuable data set in developing models and predictive codes. Data were collected at two axial locations, 0.93 and 1.26 m measured from the virtual origin. The boundary layer thickness was 20.90 mm and 24.91 mm respectively at these locations. At each position, instantaneous velocity profiles were measured at 6.35, 12.7, 20.6, 41.2, 82.3, 121.9, 164.5, 184.8, and 205.1 mm from the corner. The centerline profiles agree well with classical flat plate data. Three mean velocity and six Reynolds stress components have been calculated. The instantaneous velocity field data set is sufficient to compute higher order correlations. The data will be valuable for development of computer codes and models for heat transfer studies in the internal cooling channels of gas turbine blades and turbine end wall flow and heat transfer studies. An analysis of the data is presented. Future studies will concentrate on one smooth and one rough wall corner flow with favorable and adverse pressure gradients to provide a detailed database for corner flows in complex three dimensional flow fields.

Experimental and Fundamental Analysis of Flow in Corners: Favorable and Adverse Pressure Gradients

2004 ◽  
Author(s):  
Michael Phillips ◽  
Steve Deutsch ◽  
Arnie Fontaine ◽  
Savas Yavuzkurt
Keyword(s):  
Pressure Gradient ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Adverse Pressure Gradient ◽  
Instantaneous Velocity ◽  
Internal Cooling ◽  
Pressure Gradients ◽  
Mean Velocity ◽  
Data Set ◽  
Cooling Channels

Three dimensional instantaneous velocity data were taken in a turbulent corner flow with smooth walls under zero, a favorable, and an adverse pressure gradient. The favorable pressure gradient was −26.5 Pa/m (K = 0.15E−6) and the adverse gradient was 34.9 Pa/m (K = −0.20E−6). This paper will concentrate on effects of the favorable and adverse pressure gradients. Zero pressure gradient results were published in an earlier manuscript [1]. Experiments were carried out in air with a free stream inlet velocity of 13 m/s and an axial Reynolds number of about one million. The data were collected using a three-component LDV system that was configured in a nearly orthogonal setup. Measurements were made down to a y+ of approximately 5, and should provide a valuable data set in developing models and predictive codes. Data were collected at two axial locations, 0.93 and 1.26 m measured from the virtual origin. The boundary layer thickness was 20.90 mm and 24.91 mm respectively at these locations for the zero gradient case. The favorable gradient had thicknesses of 19.35 mm and 22.53 mm respectively, whereas the thicknesses of adverse pressure gradient were 28.89 mm and 36.81 mm. At each position, instantaneous velocity profiles were measured at 6.35, 12.7, 20.6, 41.2, 82.3, 121.9, 164.5, 184.8, and 205.1 mm from the corner. The centerline profiles agree well with classical flat plate data. Three mean velocity and six Reynolds stress components have been calculated. The instantaneous velocity field data set is sufficient to compute higher order correlations. The data will be very valuable for development of computer codes and models for corner flows of all kinds and for heat transfer studies in the internal cooling channels of gas turbine blades and turbine end wall flow. An analysis of the data is presented and will provide a detailed database for this complex three dimensional flow fields.

scholarly journals Internal Cooling Using Novel Swirl Enhancement Strategies in a Slot Shaped Single Pass Channel

2010 ◽  
Author(s):  
Del Segura ◽  
Sumanta Acharya
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Turbine Blades ◽  
Main Channel ◽  
Internal Cooling ◽  
Transfer Enhancement ◽  
Mean Velocity ◽  
Performance Factors ◽  
Air Temperatures ◽  
Rectangular Channels

Heat transfer results for a given slot shaped channel with a 3:1 aspect ratio are presented using various methods to enhance swirl in the channel including helical shaped-trip-strips and swirl-jets issuing from the side walls. Four different configurations of the swirl jets and one configuration of the helical trip strips were studied. The Reynolds numbers investigated range from 10,000 to 50,000 and are based on the mean velocity of the fluid at the channel inlet, or when swirl-jets are used, the equivalent mass flow rates at the exit of the main channel. Independently these heat transfer enhancement strategies have proven to be effective in either round channels, in the case of swirl jets and helical protrusions, or rectangular channels, in the case of trip strips. A transient technique combined with Duhamel’s superposition theorem was used to obtain the heat transfer coefficient distributions. Narrow-band liquid crystals were used to map the transient surface temperatures and were combined with thermocouples that measured the bulk-air temperatures along the flow path in the main channel. The results for the tests reported in this paper show mean heat transfer enhancement values (Nu/Nuo) greater than 4.5 and low normalized friction factors. Thermal performance factors ranged from 1.1–3.3 for the various configurations studied. These results show significant improvements over other types of heat transfer enhancement methods currently used in the mid-span section of turbine blades.

scholarly journals Development of a Thermal and Structural Analysis Procedure for Cooled Radial Turbines

1988 ◽  
Author(s):  
Ganesh N. Kumar ◽  
Russell G. Deanna
Keyword(s):  
Heat Transfer ◽  
Boundary Conditions ◽  
Three Dimensional ◽  
Internal Flow ◽  
Stream Velocity ◽  
Internal Cooling ◽  
Nasa Lewis Research ◽  
Transfer Coefficients ◽  
Cooling Flow ◽  
Radial Turbine

A procedure for computing the rotor temperature and stress distributions in a cooled radial turbine is considered. Existing codes for modeling the external mainstream flow and the internal cooling flow are used to compute boundary conditions for the heat transfer and stress analyses. An inviscid, quasi three-dimensional code computes the external free stream velocity. The external velocity is then used in a boundary layer analysis to compute the external heat transfer coefficients. Coolant temperatures are computed by a viscous one-dimensional internal flow code for the momentum and energy equation. These boundary conditions are input to a three-dimensional heat conduction code for calculation of rotor temperatures. The rotor stress distribution may be determined for the given thermal, pressure and centrifugal loading. The procedure is applied to a cooled radial turbine which will be tested at the NASA Lewis Research Center. Representative results from this case are included.

Analysis and Multi-Disciplinary Optimization of Internal Coolant Networks in Turbine Blades

2001 ◽  
Author(s):  
Thomas J. Martin ◽  
George S. Dulikravich
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Computer Program ◽  
Turbine Blade ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Coolant Fluid ◽  
Internal Cooling ◽  
Local Flow ◽  
Design And Optimization

Abstract This paper presents the theoretical methodology, conceptual demonstration, and validation of a fully automated computer program for the inverse design and optimization of internal convectively cooled three-dimensional axial gas turbine blades. A parametric computer model of the three-dimensional internal cooling network was developed, including the automatic generation of computational grids. A boundary element computer program was written to solve the steady-state non-linear heat conduction equation inside the internally cooled and thermal barrier-coated turbine blade. A finite element algorithm was written to model an arbitrary network of internal coolant passages for the calculation of the internal heat transfer coefficients, pressure losses, local flow rates, the effects of centrifugal pumping, heating of the coolant fluid, and forced convection from the thermal model of the solid to the coolant fluid. The heat conduction and internal flow analyses were iteratively coupled to account for the heat balance between the blade and the coolant fluid. The computer-automated design and optimization system was demonstrated on the second high-pressure turbine blade row of the Pratt & Whitney F100 engine. The internal cooling configuration and local heat transfer enhancements (boundary layer trip strips and pin fins) inside the three-dimensional blade were optimized for maximum cooling effectiveness and durability against corrosion and thermo-mechanical fatigue.

Effect of Coriolis and Centrifugal Forces on Turbulence and Heat Transfer at High Rotation and Buoyancy Numbers in a Rib-Roughened Internal Cooling Channel

2004 ◽  
Author(s):  
A. K. Sleiti ◽  
J. S. Kapat
Keyword(s):  
Heat Transfer ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Internal Cooling ◽  
Cooling Channel ◽  
Centrifugal Forces ◽  
Reynolds Stresses ◽  
Rsm Model ◽  
Density Ratios ◽  
Rib Roughened

Prediction of three-dimensional flow field and heat transfer in a two pass rib-roughened square internal cooling channel of turbine blades with rounded staggered ribs rotating at high rotation and density ratios is the main focus of this study. Rotation, buoyancy, ribs, and geometry affect the flow within these channels. The full two-pass channel with bend and with rounded staggered ribs with fillets (e/Dh = 0.1 and P/e = 10) as tested by Wagner et. al [1992] is investigated. RSM is used in this study and enhanced wall treatment approach to resolve the near wall viscosity-affected region. RSM model was validated against available experimental data (which are primarily at low rotation and buoyancy numbers). The model was then used for cases with high rotational numbers (0.24, 0.475, 0.74 and 1) and high-density ratios (0.13, 0.23, and 0.3). Particular attention is given to how secondary flow, Reynolds stresses, turbulence intensity, and heat transfer are affected by coriolis and buoyancy/centrifugal forces caused by high levels of rotation and density ratios. A linear correlation for 4-side-average Nusselt number as a function of rotation number is derived.

Swirl-Enhanced Internal Cooling of Turbine Blades: Part 1—Radial Flow Entry

2011 ◽  
Author(s):  
Del Segura ◽  
Sumanta Acharya
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Turbine Blades ◽  
Main Channel ◽  
Internal Cooling ◽  
Transfer Enhancement ◽  
Mean Velocity ◽  
Performance Factors ◽  
Air Temperatures ◽  
The Mean

Heat transfer results for a given slot shaped channel with a 3:1 aspect ratio and jets issuing from side walls are presented. Two different jet configurations are used as a means to enhance turbulence in the main flow stream. The Reynolds numbers investigated range from 10,000 to 50,000 and are based on the mean velocity of the fluid at the channel inlet for the slot shaped channel without enhancement, or when swirl-jets are used, the equivalent mass flow rates at the exit of the main channel. Blowing Ratios, defined as the mean side jet velocity verses the mean main channel velocity, ranged from 8.6 to 30.2. This heat transfer enhancement strategy has proven to be effective in round channels. A transient technique combined with Duhamel’s superposition theorem was used to obtain the heat transfer coefficient distributions. Narrow-band liquid crystals were used to map the transient surface temperatures and were combined with thermocouples that measured the center-line air temperatures along the flow path in the main channel. The results of the passage with jet enhancements were compared to the smooth slot channel, without any type of heat transfer enhancements. The tests results reported in this paper show mean heat transfer enhancement values (Nu/Nuo smooth) greater than 4.2 and low normalized friction factors. Thermal performance factors (OTP) ranged from 1.55–3.69 for the various configurations studied. These results show significant improvements over other types of heat transfer enhancement methods currently used in the mid-span section of turbine blades.

Heat Transfer Performance of Internal Cooling Turbine Blades Using Cutted-Root Rib Design

2020 ◽  
Author(s):  
Cong-Truong Dinh ◽  
Tai-Duy Vu ◽  
Tan-Hung Dinh ◽  
Phi-Minh Nguyen
Keyword(s):  
Heat Transfer ◽  
Gas Turbines ◽  
Heat Transfer Performance ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Navier Stokes ◽  
Internal Cooling ◽  
Transfer Performance ◽  
External Cooling

Abstract In gas turbines, the turbine blades are always working in the highly temperature overhead the permissible metal temperatures. To safe operation, the turbine blades are needed to cool. Many researchs in turbine cooling technology can be categorized as internal and external cooling. This paper presents an investigation of cutted-root rib design, where a part of rib was truncated below to create an extra-passage in the root rib applied in the internal cooling turbine blades of jet engine using three-dimensional Reynolds-averaged Navier-Stokes with the SST model. The object of this investigation is to reduce the vortex occurring near the rib for improving the performance of heat transfer, such as the Nusselt number and thermal performance factor. To investigate the heat transfer performance and fluid flow characteristics of internal cooling turbine blades, a parametric study of the cutted-root rib was performed using various geometric parameters related to the height and shapes of the extra-passage. The cutted-root rib geometry is designed in ANSYS DesignModeler, and then meshed by using ICEM-CFD, analysed and post-processed using Ansys-CFX. The numerical results showed that all heat transfer parameter with the cutted-root rib design was greater than the original case without cutted-root rib.

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.

Evaluation of the SST-SAS Model for Prediction of Separated Flow Inside Turbine Internal Cooling Passages

2016 ◽  
Author(s):  
Piotr Zacharzewski ◽  
Kathy Simmons ◽  
Richard Jefferson-Loveday ◽  
Luigi Capone
Keyword(s):  
Heat Transfer ◽  
Separation Bubble ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Separated Flow ◽  
Streamwise Velocity ◽  
Stream Velocity ◽  
Internal Cooling ◽  
Sas Model ◽  
The Hill

The flow and heat transfer over a three-dimensional axisymmetric hill and rectangular ribbed duct is computed in order to evaluate the Shear Stress Transport - Scale Adaptive Simulation (SST-SAS) turbulence model. The study presented here is relevant to turbine blade internal cooling passages and the aim is to establish whether SAS-SST is a viable alternative to other turbulence models for computations of such flows. The model investigated is based on Menter’s modification to Rotta’s k-kL model and comparison is made against experimental data as well as other models including some with scale resolving capability, such as LES, DES & hybrid LES-RANS. For the hill case the SAS model dramatically overpredicts the size of the separation bubble. The LES on the other hand proved to be more accurate even though the mesh is courser by LES standards. There is little improvement of SST-SAS compared with RANS. Broadly speaking all models predict streamwise velocity profiles for the ribbed channel with reasonable accuracy. The cross-stream velocity is underpredicted by all models. Heat transfer prediction is more accurately predicted by LES than RANS, DES & SST-SAS on a mesh that is slightly coarser than required by LES standard, however it still exhibits significant error. It is concluded that more investigation of the SST-SAS model is required to more broadly assess its viability for industrial computation.

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