Heat Transfer of Rotating Rectangular Channel With Diamond Shaped Pin-Fin Array at High Rotation Numbers

2012 ◽  
Author(s):  
S. W. Chang ◽  
T.-M. Liou ◽  
T.-H. Lee
Keyword(s):  
Heat Transfer ◽  
Rectangular Channel ◽  
Turbine Rotor ◽  
Full Field ◽  
Turbine Rotor Blade ◽  
Pin Fin ◽  
Nusselt Numbers ◽  
Static Channel ◽  
Pin Fin Array ◽  
Transfer Properties

This experimental study measured the detailed Nusselt numbers (Nu) distributions over two opposite leading and trailing walls of a rotating rectangular channel fitted with diamond shaped pin-fin array with radially outward flow for gas turbine rotor blade cooling applications. The combined and isolated effects of Reynolds (Re), rotation (Ro) and buoyancy (Bu) numbers on local and area-averaged Nusselt numbers (Nu and Nu) were examined at the test conditions of 5000≤Re≤15000, 0≤Ro≤0.6 and 0.0007≤Bu≤0.31. The present infrared thermography method enables the generation of full-field Nu scans over the rotating endwalls at the realistic engine Ro conditions as the first attempt to reveal the combined rotating buoyancy and Coriolis force effects on heat transfer properties. The selected heat transfer results demonstrate the Coriolis and rotating-buoyancy effects on the heat transfer performances of this rotating channel. Acting by the combined Coriolis and rotating buoyancy effects on the area-averaged heat transfer properties, the rotating leading and trailing area-averaged Nusselt numbers are modified respectively to 0.82–1.52 and 1–1.89 times of the static channel references. A set of physically consistent empirical Nu correlations was generated to permit the assessments of individual and interdependent Re, Ro and Bu effects on the area-averaged heat transfer properties over leading and trailing endwalls.

Heat Transfer of a Rotating Rectangular Channel With a Diamond-Shaped Pin-Fin Array at High Rotation Numbers

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
S. W. Chang ◽  
T.-M. Liou ◽  
T.-H. Lee
Keyword(s):  
Heat Transfer ◽  
Rectangular Channel ◽  
Turbine Rotor ◽  
Full Field ◽  
Turbine Rotor Blade ◽  
Pin Fin ◽  
Nusselt Numbers ◽  
Static Channel ◽  
Pin Fin Array ◽  
Transfer Properties

This experimental study measured the detailed Nusselt numbers (Nu) distributions over two opposite leading and trailing walls of a rotating rectangular channel fitted with a diamond-shaped pin-fin array with radially outward flow for gas turbine rotor blade cooling applications. The combined and isolated effects of Reynolds (Re), rotation (Ro), and buoyancy (Bu) numbers on local and area-averaged Nusselt numbers (Nu and Nu¯) were examined at the test conditions of 5000 ≤ Re ≤ 15,000, 0 ≤ Ro ≤ 0.6, and 0.0007 ≤ Bu ≤ 0.31. The present infrared thermography method enables the generation of full-field Nu scans over the rotating end walls at the realistic engine Ro conditions as the first attempt to reveal the combined rotating buoyancy and Coriolis force effects on heat transfer properties. The selected heat transfer results demonstrate the Coriolis and rotating-buoyancy effects on the heat transfer performances of this rotating channel. Acting by the combined Coriolis and rotating buoyancy effects on the area-averaged heat transfer properties, the rotating leading and trailing area-averaged Nusselt numbers are modified, respectively, to 0.82–1.52 and 1–1.89 times the static channel references. A set of physically consistent empirical Nu¯ correlations was generated to permit the assessments of individual and interdependent Re, Ro, and Bu effects on the area-averaged heat transfer properties over leading and trailing end walls.

Thermal Performance of a Radially Rotating Twin-Pass Smooth-Walled Parallelogram Channel

2014 ◽  
Vol 136 (12) ◽  
Author(s):  
Tong-Miin Liou ◽  
Shyy Woei Chang ◽  
Chun-Chang Yang ◽  
Yi-An Lan
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Turbine Rotor ◽  
Full Field ◽  
Turbine Rotor Blade ◽  
Performance Factors ◽  
Square Channel ◽  
Nusselt Numbers ◽  
The Individual ◽  
Rotating Channel

An experimental study was performed to measure the detailed heat transfer distributions, Fanning friction factors (f), and thermal performance factors (TPF) of a radially rotating twin-pass parallelogram channel. Laboratory scale full field Nusselt number (Nu) distributions over leading endwall (Leading-E), and trailing endwall (Trailing-E) of the rotating channel are measured at the test conditions of 5000 < Re < 20,000, 0 < Ro < 0.3 and 0.028 < Δρ/ρ < 0.12. A selection of Nu data illustrates the individual and interactive impacts of Re, Ro, and buoyancy (Bu) numbers on local and area-averaged heat transfer properties. Without the additional flow complexities induced by the turbulators, the degrees of Bu impacts are significantly amplified from those developed in an enhanced rotating ribbed channel. Relative to the similar rotating square twin-pass channel, the heat transfer recovery over the stable wall proceeds at the lower Ro for present rotating parallelogram channel. Accompanying with the improved heat transfer performances from the square-channel counterparts, the f values are raised. With a set of f correlations generated using the f data collected from the Leading-S and Trailing-S at isothermal conditions; the TPF values at various rotating conditions were evaluated. The heat transfer correlations that determine the area-averaged Nusselt numbers over the inlet and outlet legs and over the turning region are generated. The area-averaged Nu, f factors, and TPF determined from the present rotating parallelogram channel are compared with those reported for the rotating twin-pass channels to determine the comparatively thermal performances of the parallelogram rotating channel for turbine rotor blade cooling.

Thermal Performance of a Radially Rotating Twin-Pass Smooth-Walled Parallelogram Channel

2014 ◽  
Author(s):  
Tong-Miin Liou ◽  
Shyy Woei Chang ◽  
Chun-Chang Yang ◽  
Yi-An Lan
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Turbine Rotor ◽  
Full Field ◽  
Turbine Rotor Blade ◽  
Performance Factors ◽  
Square Channel ◽  
Nusselt Numbers ◽  
The Individual ◽  
Rotating Channel

An experimental study was performed to measure the detailed heat transfer distributions, Fanning friction factors (f) and thermal performance factors (TPF) of a radially rotating twin-pass parallelogram channel. Laboratory scale full field Nusselt number (Nu) distributions over Leading Endwall (Leading-E) and Trailing Endwall (Trailing-E) of the rotating channel are measured at the test conditions of 5000 < Re < 20000, 0 < Ro < 0.3 and 0.028 < Δρ/ρ < 0.12. A selection of Nu data illustrates the individual and interactive impacts of Re, Ro and buoyancy (Bu) numbers on local and area-averaged heat transfer properties. Without the additional flow complexities induced by the turbulators, the degrees of Bu impacts are significantly amplified from those developed in an enhanced rotating ribbed channel. Relative to the similar rotating square twin-pass channel, the heat transfer recovery over the stable wall proceeds at the lower Ro for present rotating parallelogram channel. Accompanying with the improved heat transfer performances from the square-channel counterparts, the f values are raised. With a set of f correlations generated using the f data collected from the Leading Sidewall (Leading-S) and Trailing Sidewall (Trailing-S) at isothermal conditions; the TPF values at various rotating conditions were evaluated. The heat transfer correlations that determine the area-averaged Nusselt numbers over the inlet and outlet legs and over the turning region are generated. The area-averaged Nu, f factors and TPF determined from the present rotating parallelogram channel are compared with those reported for the rotating twin-pass channels to determine the comparatively thermal performances of the parallelogram rotating channel for turbine rotor blade cooling.

Influences of the Non-Uniform Pin-Fin Array on Heat Transfer Distribution in a Rotating Rectangular Channel

2018 ◽  
Author(s):  
Shuo-Cheng Hung ◽  
Szu-Chi Huang ◽  
Yao-Hsien Liu
Keyword(s):  
Heat Transfer ◽  
Rectangular Channel ◽  
Reynolds Numbers ◽  
Stationary Case ◽  
Pin Fin ◽  
Liquid Crystal Thermography ◽  
Staggered Arrangement ◽  
Channel Orientation ◽  
Pin Fin Array ◽  
Pin Fin Arrays

The liquid crystal thermography was used to investigate the heat transfer of non-uniform pin-fin arrays in a rotating rectangular channel (AR = 4:1) at a channel orientation of 135°. The pin-fin array consisted of four and three pins in a staggered arrangement. The different sized pins were inserted at the rows exhibiting four pins, which produced a non-uniform distribution of the pin-fin array. The experiments were operated at Reynolds numbers of 10,000 and 20,000 for both stationary and rotating conditions. The rotation number varied from 0 to 0.33 and the buoyancy parameter ranged from 0 to 0.27. Results indicated that various heat transfer contours were observed as a result of flow separation and vortices caused by non-uniform pins. Compared to the stationary case, rotation increased heat transfer on both trailing and leading surfaces. The pin-fin array consisted of 6 and 9 mm pins produced the highest heat transfer and frictional losses under rotation condition.

scholarly journals Pressure Drop Distribution in a Rotating Rectangular Channel With One Ribbed Surface

1997 ◽  
Author(s):  
S. V. Prabhu ◽  
R. P. Vedula
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Friction Factor ◽  
Flow Direction ◽  
Rectangular Channel ◽  
Turbine Rotor ◽  
Internal Cooling ◽  
Transfer Coefficients ◽  
Turbine Rotor Blade ◽  
Blade Thickness

A modified geometry for the internal cooling passages of a gas turbine rotor blade is suggested here. In this modified geometry, the Coriolis force induced enhanced heat transfer coefficients are experienced by both the coolant channel walls adjacent to the blade pressure and blade suction surfaces. This is made possible by permitting the flow to have a radially outward and a radially inward direction at different locations along the blade thickness at a given chordwise location. However, the flow geometry is complex and the corresponding pressure losses are also likely to be larger. The present investigation is a preliminary study of the pressure drop characteristics for the modified channel suggested above and the simplest case of a straight channel with ribs on only one surface is reported here. The pressure drop in a rectangular cross-sectioned duct with an aspect ratio of 2.0 rotating about an axis normal to the free-stream direction in the presence of rib turbulators glued on one of the surfaces of the test section with ribs normal to the flow direction is measured. The study has been conducted for Reynolds number varying from 10000–17000 and the rotation number varying from 0–0.21. Experiments were carried out for various pitch-to-rib height ratios (P/e) of 3, 5, 7.5 & 10 with a constant rib height-to-hydraulic diameter ratio (e/D) of 0.15. A significant increase of the friction factor is observed when the ribbed surface is the coolant channel trailing (pressure) surface in the presence of rotation. The highest friction factor is observed in a channel with a P/e ratio of 5 which would imply that there could be a significant increase in the heat transfer coefficient for this configuration. A pitch-to-height ratio of about 10, which is the most preferred choice for a stationary configuration, no longer appears to be the optimum in the presence of rotation.

The Effects of Different Pin-Fin Arrays on Heat Transfer and Pressure Loss in a Narrow Channel

2015 ◽  
Author(s):  
Sin Chien Siw ◽  
Austen D. Fradeneck ◽  
Minking K. Chyu ◽  
Mary Anne Alvin
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Pressure Loss ◽  
Rectangular Channel ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Hybrid Technique ◽  
Pin Fin ◽  
Smooth Channel ◽  
Pin Fin Array

This paper describes a detailed experimental investigation of a narrow rectangular channel based on the double-wall cooling concept that can be applicable to a gas turbine airfoil. The channel has dimensions of 63.5 mm by 12.7 mm, corresponding to an aspect ratio of 5:1. The pin diameter, D, is 12.7 mm, and the ratio of pin-height-to-diameter, H/D is 1. The inter-pin spacing is varies in both spanwise and streamwise directions to form two inline, and two staggered pin-fin configurations. The Reynolds number, based on the hydraulic diameter of the pin fin and the mean bulk velocity, ranges from 6,000 to 15,000. The experiments employ a hybrid technique based on transient liquid crystal imaging to obtain the distributions of the local heat transfer coefficient over all of the participating surfaces, including the endwalls and all the pin elements. The heat transfer on both the endwall and pin-fin surfaces revealed similar pattern compared to the typical circular pin-fin array, which were conducted at higher Reynolds number. The total heat transfer enhancement of current pin-fin array is approximately four times higher than that of fully developed smooth channel with low pressure loss, which resulted in much higher thermal performance compared to other pin-fin array as reported in the literature.

Heat Transfer and Pressure Loss Characteristics of a Narrow Internal Cooling Passage at Low Reynolds Number

2014 ◽  
Author(s):  
Sin Chien Siw ◽  
Nicholas Miller ◽  
Minking K. Chyu ◽  
Mary Anne Alvin
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Pressure Loss ◽  
Rectangular Channel ◽  
Internal Cooling ◽  
Hybrid Technique ◽  
Pin Fin ◽  
Smooth Channel ◽  
Cooling Passage ◽  
Pin Fin Array

This paper describes a detailed experimental investigation of a narrow rectangular channel based on the double-wall cooling concept that can be applicable to a gas turbine airfoil. The channel has dimensions of 63.5 mm by 12.7 mm, corresponding to an aspect ratio of 5:1. A single pin-fin element, arranged in 9 rows is fitted into the channel. The pin diameter, D, is 12.7 mm, and the ratio of pin-height-to-diameter, H/D is 1. The pins are arranged based on the typical inter-pin spacing of 2.5D in both spanwise and streamwise directions. The Reynolds number, based on the hydraulic diameter of the pin fin and the mean bulk velocity, ranges from 6,000 to 15,000. The experiments employ a hybrid technique based on transient liquid crystal imaging to obtain the distributions of the local heat transfer coefficient over all of the participating surfaces, including the endwalls and all the pin elements. Commercially available CFD software, ANSYS CFX, is used to qualitatively correlate the experimental results and to provide detailed insights of the flow field created by the array.The heat transfer on both the endwall and pin-fin surfaces revealed similar pattern compared to the typical circular pin-fin array, which were conducted at higher Reynolds number. The total heat transfer enhancement of current pin-fin array is approximately five times higher than that of fully developed smooth channel with low pressure loss, which resulted in much higher thermal performance compared to other pin-fin array as reported in the literature.

Experimental Investigation Into the Influence of Varying Stagger on the Performance of a Pin-Fin Array

2008 ◽  
Author(s):  
W. D. Allan ◽  
S. A. Andrews ◽  
M. LaViolette
Keyword(s):  
Heat Transfer ◽  
Friction Factor ◽  
Pressure Loss ◽  
Reynolds Numbers ◽  
Design Criterion ◽  
Transfer Enhancement ◽  
Pin Fin ◽  
Line Array ◽  
Array Performance ◽  
Pin Fin Array

A six row pin-fin array was constructed with a spanwise spacing of 2.5 diameters, streamwise spacing of 1.5 diameters and a height to diameter ratio of 1. The streamwise stagger of alternate rows was continuously varied from fully in-line to fully staggered. Tests were carried out at Reynolds numbers of 2.7 × 104 and 2.3 × 104, corresponding to maximum velocities, in the low subsonic range, of 21 m/s and 18 m/s respectively. These results showed that the array averaged heat transfer was greatest from a fully staggered array and had a minimum at a stagger slightly greater than fully in-line. However, with increasing stagger, the array-averaged friction factor grew at a greater rate than the heat transfer. The ensuing analysis of the total array performance, considering both the magnitude of heat transfer and the losses within the array, showed that the fully in-line array had the highest ratio of heat transfer enhancement to friction factor enhancement. Therefore, if pressure loss was a design criterion, the fully in-line array was preferable. However, if pressure loss was not a constraint, then the staggered array was preferable.

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