Numerical Evaluation of Pin Fin Inclination by Conjugate Heat Transfer Simulation With URANS

2015 ◽  
Author(s):  
Takashi Yamane
Keyword(s):  
Heat Transfer ◽  
Thermal Conduction ◽  
Conjugate Heat Transfer ◽  
Turbine Blades ◽  
Flow Region ◽  
Cooling Performance ◽  
Pin Fin ◽  
Blade Cooling ◽  
Pin Fins ◽  
Heat Transfer Simulation

Short pin fins are often used as one of the blade cooling technologies inside the trailing edge of turbine blades. In our previous study we focused on the effects of pin inclination for overall cooling performance especially including heat conduction between the pins and endwall by both experiments and the conjugate heat transfer simulations, then the forwardly inclined pin-fins are found to effectively enhance the cooling, but we also found that the steady conjugate heat transfer simulation underestimates the cooling performance of the straight pin-fins due to highly unsteady flow structure. In this study the URANS is coupled with the steady thermal conduction by using the time smoothing method in the flow region, thus the underestimate of the heat transfer for the straight pin-fins was significantly improved.

Effect of Corrugated Orifice and Pin-Fin on Multiple Array Impingement Cooling With Low Nozzle to Target Distance

2014 ◽  
Author(s):  
Li Yang ◽  
Weihong Li ◽  
Zhongran Chi ◽  
Jing Ren ◽  
Hongde Jiang
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Conjugate Heat Transfer ◽  
High Heat ◽  
Inlet Temperature ◽  
Impingement Cooling ◽  
Pin Fin ◽  
High Heat Transfer ◽  
Pin Fins ◽  
Heat Transfer Simulation

Impingement cooling is widely used in turbine vanes and combustors. With the increase of turbine inlet temperature, high heat transfer coefficient and low pressure drop are required for cooling structures. A series of new impingement configurations combined with corrugated orifice and pin-fins were developed in the present work. Both transient liquid crystal (TLC) and pressure measurement were applied on the impingement cooling structures. A 3D numerical method was also used for conjugate heat transfer simulation. Corrugated orifice helps decrease the pressure drop by decreasing the speed of cross flow. Experimental data show that, corrugated orifice is helpful in reducing pin-fin induced pressure drop but contributes little to heat transfer. Pin-fins increases both the heat transfer and pressure drop lightly. Conjugate heat transfer simulation shows that pin-fins significantly reduce the metal temperature by conduction. Structures with pin-fins can make a good use of the large surface area of corrugated orifices.

Elliptical Pin Fins as an Alternative to Circular Pin Fins for Gas Turbine Blade Cooling Applications: Part 1 — Endwall Heat Transfer and Total Pressure Loss Characteristics

2001 ◽  
Author(s):  
Oğuz Uzol ◽  
Cengiz Camci
Keyword(s):  
Heat Transfer ◽  
Pressure Loss ◽  
Total Pressure ◽  
Major Axis ◽  
Total Pressure Loss ◽  
Turbine Blade Cooling ◽  
Pin Fin ◽  
Blade Cooling ◽  
Pin Fins ◽  
Pin Fin Arrays

Detailed experimental investigation of the wall heat transfer enhancement and total pressure loss characteristics for two alternative elliptical pin fin arrays is conducted and the results are compared to the conventional circular pin fin arrays. Two different elliptical pin fin geometries with different major axis lengths are tested, both having a minor axis length equal to the circular fin diameter and positioned at zero degrees angle of attack to the free stream flow. The major axis lengths for the two elliptical fins are 1.67 and 2.5 times the circular fin diameter, respectively. The pin fin arrays with H/D = 1.5 are positioned in a staggered 2 row configuration with 3 fins in the first row and 2 fins in the second row with S/D = X/D = 2. Endwall heat transfer and total pressure loss measurements are performed two diameter downstream of the pin fin arrays (X/D = 2) in a rectangular cross-section tunnel with an aspect ratio of 4.8 and for varying Reynolds numbers between 10000 and 47000 based on the inlet velocity and the fin diameter. Liquid Crystal Thermography is used for the measurement of convective heat transfer coefficient distributions on the endwall inside the wake. The results show that the wall heat transfer enhancement capability of the circular pin fin array is about 25–30% higher than the elliptical pin fin arrays in average. However in terms of total pressure loss, the circular pin fin arrays generate 100–200% more pressure loss than the elliptical pin fin arrays. This makes the elliptical fin arrays very promising cooling devices as an alternative to conventional circular pin fin arrays used in gas turbine blade cooling applications.

Conjugate Heat Transfer Enhancement of an Internal Blade Pin-Finned Tip-Wall

2009 ◽  
Author(s):  
Gongnan Xie ◽  
Bengt Sunde´n
Keyword(s):  
Heat Transfer ◽  
Turbine Blade ◽  
Conjugate Heat Transfer ◽  
Gas Flow ◽  
Turbine Blades ◽  
Thermal Design ◽  
Inlet Temperature ◽  
Computational Domain ◽  
Pin Fins ◽  
Blade Tip

To improve gas turbine performance, the operating temperature has been increased continuously. However, the heat transferred to the turbine blade is substantially increased as the turbine inlet temperature is increased. Cooling methods are therefore needed for the turbine blades to ensure a long durability and safe operation. The blade tip region is exposed to the hot gas flow and is difficult to cool. A common way to cool the tip is to use serpentine passages with 180-deg turn under the blade tip-cap taking advantage of the three-dimensional turning effect and impingement. Increasing internal convective cooling is therefore required to increase the blade tip life. In this paper, augmented heat transfer of a blade tip with internal pin-fins has been investigated numerically using a conjugate heat transfer approach. The computational model consists of a two-pass channel with 180-deg turn and an array of pin-fins mounted on the tip-cap. The computational domain includes the fluid region and the solid pins as well as the solid tip regions. Turbulent convective heat transfer between the fluid and pins, and heat conduction within pins and tip are simultaneously computed. The inlet Reynolds numbers are ranging from 100,000 to 600,000. Details of the 3D fluid flow and heat transfer over the tip surface are presented. A comparison of the overall performance of the two models is presented. It is found that due to the combination of turning impingement and pin-fin cross flow, the heat transfer coefficient of the pin-finned tip is a factor of about 3.0 higher than that of a smooth tip. This augmentation is achieved at the cost of a pressure drop penalty of about 7%. With the conjugate heat transfer method, not only the simulated model is close to the experimental model, but also the distribution of the external tip heat transfer can be relevant for thermal design of turbine blade tips.

Impingement Jet Cooling With Ribs and Pin Fin Obstacles in Co-Flow Configurations: Conjugate Heat Transfer Computational Fluid Dynamic Predictions

2016 ◽  
Author(s):  
Abubakar M. El-Jummah ◽  
Gordon E. Andrews ◽  
John E. J. Staggs
Keyword(s):  
Heat Transfer ◽  
Pressure Loss ◽  
Conjugate Heat Transfer ◽  
Coolant Flow ◽  
Experimental Results ◽  
Hole Density ◽  
Flow Rates ◽  
Pin Fin ◽  
Impingement Jet ◽  
Pin Fins

Conjugate heat transfer (CHT) computational fluid dynamics (CFD) predictions were carried out for impingement heat transfer with obstacle (fins) walls on the target surface midway between the impingement jets and aligned in the direction of the crossflow (direction of outflow of the impingement cooling air) to minimise the pressure loss increase due to the fins. A single sided flow exit was used in a geometry that was applicable to reverse flow cooling of low NOx combustors, but was also relevant to turbine blade and nozzle cooling. A 10 × 10 row of impingement jet holes (hole density n of 4306 m−2) was used, which had ten rows of holes in the cross-flow direction. One heat transfer enhancement obstacle per impingement jet was investigated and compared with previously published experimental results, for Nimonic 75 metal walls, for flow pressure loss and surface averaged heat transfer coefficients. Two different shaped obstacles were investigated with an impingement gap, Z, of 10mm: a continuous rectangular rib 4.5mm high (H) and 3.0 mm thick and a rectangular pin-fin rib with ten 8mm high (H) pins that were 8.6mm wide and 3.0 mm thick. The obstacles were equally spaced on the centreline between each row of impingement jets aligned with the crossflow. The impingement jet pitch to diameter X/D and gap to diameter Z/D ratios were kept constant at 4.66 and 3.06 for X, Z and D of 15.24, 10.00 and 3.27 mm, respectively. The two obstacles investigated had obstacle height to diameter ratio H/D of 1.38 and 2.45. The computations were carried out for three different air coolant mass fluxes G of 1.08, 1.48 and 1.94 kg/sm2bar. The pressure loss ΔP/P and surface average heat transfer coefficient (HTC) h predictions for all three G showed good agreement with the experimental results. The predicted results were also compared with the impingement jet single exit flow, for a smooth target wall of the same impingement hole configuration. A significant increase in the overall surface averaged heat transfer was predicted and measured for the co-flow configuration with rectangular pin-fins. This was a 20% improvement at low coolant flow rates for the rectangular pin fin obstacles and 15% for the ribs. At high coolant flow rates the improvement was smaller at 5% for the rectangular pin fins and 1% for the rectangular ribs.

scholarly journals Simulation of Impinging Cooling Performance with Pin Fins and Mist Cooling Adopted in a Simplified Gas Turbine Transition Piece

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Tao Xu ◽  
Hang Xiu ◽  
Junlou Li ◽  
Haichao Ge ◽  
Qing Shao ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Weighted Average ◽  
Two Phase ◽  
Cooling Performance ◽  
Pin Fin ◽  
Pin Fins ◽  
Mist Cooling ◽  
Transition Piece ◽  
Impinging Cooling

The gas turbine transition piece was simplified to a one-four cylinder double chamber model with a single row of impinging holes in the outer wall. Heat transfer augmentation in the coolant chamber was achieved through the use of pin fin structure and mist cooling, which could increase the turbulence and heat transfer efficiency. The present research is focused on heat transfer and pressure characteristics of the impinging cooling in the coolant chamber using FLUENT software. With the given diameter of impinging hole, pin fin diameter ratiosD/dhave been numerically studied in ranges from 1 to 2. Three different detachedLwere simulated. The impinging cooling performance in all cases was compared between single-phase and two-phase (imported appropriate mist) flow in the coolant chamber. All the simulation results reveal that the factors ofLandD/dhave significant effects on the convective heat transfer. After the pin fin structure was taken, the resulting temperature decrease of 38.77 K at most compared with the result of structure without pin fins. And with the mist injecting into the cooling chamber, the area weighted average temperature got a lower value without excess pressure loss, which could satisfy the more stringent requirements in engineering.

Flow Field Around Dimpled Pin-Fins in a Staggered Array

2011 ◽  
Author(s):  
R. K. Nagar ◽  
J. P. Meyer ◽  
Md. MahbubAlam ◽  
G. Spedding
Keyword(s):  
Heat Transfer ◽  
Cross Section ◽  
Turbine Blades ◽  
Circular Cross Section ◽  
Enhanced Heat Transfer ◽  
Enhance Heat Transfer ◽  
Transfer Rates ◽  
Pin Fin ◽  
Low Aspect Ratio ◽  
Pin Fins

Pin fins are low aspect ratio rods of circular cross section that are used to enhance heat transfer inside turbine blades. Although modifying the basic circular geometry with numerous shallow depressions (dimples) has been linked with enhanced heat transfer rates, the fluid mechanical mechanisms have remained speculative. Here we investigate numerically the effects of dimples onthe mean and turbulence velocities that lead to increased heat transfer. It has been found that dimples result in an increased turbulence intensity which may possess a greater potential to extract and transport more heat from the pin-fin.

Numerical Study on Heat Transfer and Fluid Flow in Pin Fin-Dimple Channels With Fillet on Dimple Edge

2014 ◽  
Author(s):  
Muralikrishnan Gopalakrishnan Meena ◽  
Abhijith Anandakrishnan ◽  
Madhu Anandarajan Kavumcheril
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Turbine Blades ◽  
Constant Heat Flux ◽  
Original Structure ◽  
Frictional Loss ◽  
Modified Model ◽  
Pin Fin ◽  
Pin Fins ◽  
Work Done

Pin fins and dimples are used for enhancing heat transfer from surfaces and here we take into account their use in cooling the trailing edge of gas turbine blades. The main problem is the increase in pressure drop with increase in dimple depths. This is a vital factor for the total work done by the turbine. The models for which study has been conducted are the ones with dimple depths of 1mm, 2mm and 3mm. Also, as a modification, fillets are added to the edges of the dimples with 3mm depth. Turbulent flow with Re of about 55,000 is employed through the surface, which is heated with constant heat flux of 50,000 W/m2. The results showed that the modified model reduces the frictional loss to a large extent without creating much disturbance to the heat transfer capability of the original structure. The modified model gave the lowest amount of friction factor at the same time providing reasonable amount of heat transfer compared to the other three models.

Augmented Heat Transfer of Internal Blade Tip Wall With Pin-Fins

2009 ◽  
Author(s):  
G. N. Xie ◽  
B. Sunde´n ◽  
L. Wang ◽  
E. Utriainen
Keyword(s):  
Heat Transfer ◽  
Computational Models ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Inlet Temperature ◽  
Gas Flows ◽  
Pin Fin ◽  
Pin Fins ◽  
Blade Tip

The heat transferred to the turbine blade is substantially increased as the turbine inlet temperature is increased. Cooling methods are therefore much needed for the turbine blades to ensure a long durability and safe operation. The blade tip region is exposed to the hot gas flows. A common way to cool the tip is to use serpentine passages with 180-deg turn under the blade tip cap taking advantage of the three-dimensional turning effect and impingement. Improving internal convective cooling is therefore required to increase the blade tip life. In this paper, augmented heat transfer of a blade tip has been investigated numerically. The computational models consist of a two-pass channel with 180-deg turn and an array of pin-fins mounted on the tip-cap, and a smooth two-pass channel. Inlet Reynolds numbers are ranging from 100,000 to 600,000. The computations are 3D, steady, incompressible and stationary. The detailed 3D fluid flow and heat transfer over the tip surfaces are presented. The overall performance of the two models is evaluated. It is found that the pin-fins make the counter-rotating vortices towards pin-fin surfaces, resulting in continuous turbulent mixing near the pin-finned tip. Due to the combination of turning, impingement and pin-fin crossflow, the heat transfer coefficient of the pin-finned tip is a factor of as much as 1.84 higher than that of a smooth tip. This augmentation is achieved at the expense of a penalty of pressure drop around 35%. It is suggested that the pin-fins could be used to enhance blade tip heat transfer and cooling.

Sign in / Sign up

Export Citation Format

Share Document