scholarly journals Heat Transfer Characteristics of an Integrated Cooling Configuration for Ultra-High Temperature Turbine Blades: Experimental and Numerical Investigations

2001 ◽  
Author(s):  
K. Funazaki ◽  
Y. Tarukawa ◽  
T. Kudo ◽  
S. Matsuno ◽  
R. Imai ◽  
...  
Keyword(s):  
Heat Transfer ◽  
High Temperature ◽  
Cooling System ◽  
Test Model ◽  
Heat Transfer Characteristics ◽  
Target Plate ◽  
Impingement Cooling ◽  
Numerical Investigations ◽  
Transfer Characteristics ◽  
Ultra High Temperature

This paper deals with fundamental research on heat transfer characteristics inside a cooling configuration designed for an ultra-high temperature turbine nozzle. The cooling configuration adopted in this study integrates impingement cooling and pin cooling devices into one body, aiming at the enhancement of the effective area for the impingement cooling. A large-scaled test model of this cooling system is constructed to measure its internal heat transfer distribution, where a number of pins are sandwiched between an impingement plate and a target plate. The target plate are provided with several air discharging holes. A focus of this study is on how the heat transfer characteristics depend on the effect of stand-off distance: a distance between these two plates. Ratios of the stand-off distance to the impingement hole diameter varies from 0.75 to 2.00. A transient measurement technique using narrow-banded thermochromatic liquid crystal (TLC) is employed to determine the heat transfer characteristics of the model. Numerical investigations using a commercial CFD code are also executed and those results are compared with the experimental data. It is accordingly found that the numerical results almost match the measurements. It is also shown that the addition of pins to the conventional impingement cooling system can produce about 50% increase in the effective cooling area.

Heat Transfer Characteristics of Downward Facing Hot Horizontal Surfaces Using Mist Jet Impingement

2017 ◽  
Author(s):  
Ashutosh Kumar Yadav ◽  
Parantak Sharma ◽  
Avadhesh Kumar Sharma ◽  
Mayank Modak ◽  
Vishal Nirgude ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Surface Heat Flux ◽  
Cooling System ◽  
Water Pressure ◽  
Jet Impingement ◽  
Surface Heat ◽  
Heat Transfer Characteristics ◽  
Impingement Cooling ◽  
Transfer Characteristics

Impinging jet cooling technique has been widely used extensively in various industrial processes, namely, cooling and drying of films and papers, processing of metals and glasses, cooling of gas turbine blades and most recently cooling of various components of electronic devices. Due to high heat removal rate the jet impingement cooling of the hot surfaces is being used in nuclear industries. During the loss of coolant accidents (LOCA) in nuclear power plant, an emergency core cooling system (ECCS) cool the cluster of clad tubes using consisting of fuel rods. Controlled cooling, as an important procedure of thermal-mechanical control processing technology, is helpful to improve the microstructure and mechanical properties of steel. In industries for heat transfer efficiency and homogeneous cooling performance which usually requires a jet impingement with improved heat transfer capacity and controllability. It provides better cooling in comparison to air. Rapid quenching by water jet, sometimes, may lead to formation of cracks and poor ductility to the quenched surface. Spray and mist jet impingement offers an alternative method to uncontrolled rapid cooling, particularly in steel and electronics industries. Mist jet impingement cooling of downward facing hot surface has not been extensively studied in the literature. The present experimental study analyzes the heat transfer characteristics a 0.15mm thick hot horizontal stainless steel (SS-304) foil using Internal mixing full cone (spray angle 20 deg) mist nozzle from the bottom side. Experiments have been performed for the varied range of water pressure (0.7–4.0 bar) and air pressure (0.4–5.8 bar). The effect of water and air inlet pressures, on the surface heat flux has been examined in this study. The maximum surface heat flux is achieved at stagnation point and is not affected by the change in nozzle to plate distance, Air and Water flow rates.

Extensive Studies on Internal and External Heat Transfer Characteristics of Integrated Impingement Cooling Structures for HP Turbines

2008 ◽  
Author(s):  
Ken-Ichi Funazaki ◽  
Hamidon Bin Salleh
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Cooling System ◽  
External Heat ◽  
Heat Transfer Characteristics ◽  
Impingement Cooling ◽  
External Heat Transfer ◽  
Transfer Characteristics ◽  
Test Models ◽  
Film Cooling Holes

This paper deals with experimental and computational studies on internal and external heat transfer characteristics of advanced impingement cooling units combined with pin-fin cooling as well as film cooling, which is called integrated impingement cooling structure. This integrated cooling structure can be employed in the not too distant future as a simple model of quasi-transpiration cooling system for ultra high TIT (Turbine Inlet Temperature) aeroengines or gas turbines. The present study is motivated by the study of Nakamata et al. (2005) who carried out a series of studies on the integrated impingement cooling system. They found that several arrangements of impingement holes and film cooling holes mutually staggered with respect to pins yielded better cooling performance than other non-staggered configurations, although there was no evidence-based explanations shown in their study on the flow physics happening in the cooling models. Therefore, two large-scaled acrylic-resin test models with different arrangements of the impingement and film cooling holes around the pins are made in the present study, emulating the specimens used by Nakamata et al., to evaluate internal and external heat transfer coefficients as well as film effectiveness of the test models. This study accordingly aims at clarification of the reason for the clear distinction in cooling efficiency observed by Nakamata et al. between those two different cooling configurations. The measurement technique employed is a transient method using thermochromic liquid crystal to determine not only heat transfer coefficient but also film effectiveness at the same time. Steady RANS simulation is also executed using ANSYS CFX-10 to acquire detailed information on the flow behaviors and heat transfer characteristics inside and outside the cooling systems. The experimental data, along with the numerical information, reveal that the observed difference in cooling efficiency is can be explained mainly by the difference in internal heat transfer coefficient over the target plate, indicating that the pin arrangement around the impingement jet is an important factor in order to attain higher cooling performance of the proposed integrated impingement cooling system.

scholarly journals Investigations of Flow and Heat Transfer Characteristics in a Channel Impingement Cooling Configuration with a Single Row of Water Jets

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4327
Author(s):  
Min-Seob Shin ◽  
Santhosh Senguttuvan ◽  
Sung-Min Kim
Keyword(s):  
Heat Transfer ◽  
Local Heat Transfer ◽  
Target Surface ◽  
Channel Height ◽  
Heat Transfer Characteristics ◽  
Transfer Coefficients ◽  
Impingement Cooling ◽  
Average Heat ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer

The present study experimentally and numerically investigates the effect of channel height on the flow and heat transfer characteristics of a channel impingement cooling configuration for various jet Reynolds numbers in the range of 2000–8600. A single array consisting of eleven jets with 0.8 mm diameter injects water into the channel with 2 mm width at four different channel heights (3, 4, 5, and 6 mm). The average heat transfer coefficients at the target surface are measured by maintaining a temperature difference between the jet exit and the target surface in the range of 15–17 °C for each channel height. The experimental results show the average heat transfer coefficient at the target surface increases with the jet Reynolds number and decreases with the channel height. An average Nusselt number correlation is developed based on 85 experimentally measured data points with a mean absolute error of less than 4.31%. The numerical simulation accurately predicts the overall heat transfer rate within 10% error. The numerical results are analyzed to investigate the flow structure and its effect on the local heat transfer characteristics. The present study advances the primary understanding of the flow and heat transfer characteristics of the channel impingement cooling configuration with liquid jets.

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