Heat Transfer and Flow Characteristics of an Engine Representative Impingement Cooling System

2000 ◽  
Author(s):  
Changmin Son ◽  
David Gillespie ◽  
Peter Ireland ◽  
Geoffrey M. Dailey
Keyword(s):  
Heat Transfer ◽  
Liquid Crystal ◽  
Large Scale ◽  
Cooling System ◽  
Scale Model ◽  
Flow Visualisation ◽  
Surface Shear Stress ◽  
Surface Shear ◽  
Impingement Cooling ◽  
Energy Balance Approach

A study of a large-scale model of an engine representative impingement cooling system has been performed. A series of tests have been carried out to fully characterise the behaviour of the system. These include cold flow diagnostic tests to determine the pressure loss and the static pressure distribution, and flow visualisation to assess surface shear. The surface shear stress pattern provided by multiple stripes of coloured paint applied to the target surface yielded important information on the near wall flow features far from the jet axis. The row solved flow and pressure distributions are compared to industry standard predictions. Heat transfer tests using the transient liquid crystal technique were also conducted using coatings comprised of a mixture of three thermochromic liquid crystals. Analysis of the thermochromic liquid crystal data was enhanced by recent developments in image processing. In addition, an energy balance approach to analysing signals from fast response thermocouples for air temperature measurement was applied to verify the levels of heat transfer coefficients on surfaces not coated with the temperature sensitive liquid crystal.

Heat Transfer and Flow Characteristics of an Engine Representative Impingement Cooling System

2000 ◽  
Vol 123 (1) ◽  
pp. 154-160 ◽  
Author(s):  
Changmin Son ◽  
David Gillespie ◽  
Peter Ireland ◽  
Geoffrey M. Dailey
Keyword(s):  
Heat Transfer ◽  
Liquid Crystal ◽  
Large Scale ◽  
Cooling System ◽  
Scale Model ◽  
Temperature Sensitive ◽  
Surface Shear Stress ◽  
Transfer Coefficients ◽  
Surface Shear ◽  
Impingement Cooling

A study of a large-scale model of an engine representative impingement cooling system has been performed. A series of tests were carried out to characterize the behavior of the system fully. These included cold flow diagnostic tests to determine the pressure loss and the static pressure distribution, and flow visualization to assess surface shear. The surface shear stress pattern provided by multiple stripes of colored paint applied to the target surface yielded important information on the near-wall flow features far from the jet axis. The row solved flow and pressure distributions are compared to industry standard predictions. Heat transfer tests using the transient liquid crystal technique were also conducted using coatings comprised of a mixture of three thermochromic liquid crystals. Analysis of the thermochromic liquid crystal data was enhanced by recent developments in image processing. In addition, an energy balance analysis of signals from fast-response thermocouples for air temperature measurement was applied to verify the levels of heat transfer coefficients on surfaces not coated with the temperature-sensitive liquid crystal.

The Effect of Initial Cross Flow on the Cooling Performance of a Narrow Impingement Channel

2005 ◽  
Vol 127 (4) ◽  
pp. 358-365 ◽  
Author(s):  
Andrew C. Chambers ◽  
David R. H. Gillespie ◽  
Peter T. Ireland ◽  
Geoffrey M. Dailey
Keyword(s):  
Heat Transfer ◽  
Large Scale ◽  
Heat Transfer Performance ◽  
Cooling System ◽  
Cross Flow ◽  
Scale Model ◽  
Transfer Performance ◽  
Test Technique ◽  
Turbine Blade Cooling ◽  
Turbine Cooling

Impingement channels are often used in turbine blade cooling configurations. This paper examines the heat transfer performance of a typical integrally cast impingement channel. Detailed heat transfer coefficient distributions on all heat transfer surfaces were obtained in a series of low temperature experiments carried out in a large-scale model of a turbine cooling system using liquid crystal techniques. All experiments were performed on a model of a 19-hole, low aspect ratio impingement channel. The effect of flow introduced at the inlet to the channel on the impingement heat transfer within the channel was investigated. A novel test technique has been applied to determine the effect of the initial cross flow on jet penetration. The experiments were performed at an engine representative Reynolds number of 20,000 and examined the effect of additional initial cross flow up to 10 percent of the total mass flow. It was shown that initial cross flow strongly influenced the heat transfer performance with just 10 percent initial cross flow able to reduce the mean target plate jet effectiveness by 57 percent.

Cooling Performance of a Narrow Impingement Channel Including the Introduction of Cross Flow Upstream of the First Hole

2003 ◽  
Author(s):  
Andrew C. Chambers ◽  
David R. H. Gillespie ◽  
Peter T. Ireland ◽  
Geoffrey M. Dailey
Keyword(s):  
Heat Transfer ◽  
Large Scale ◽  
Cooling System ◽  
Cross Flow ◽  
Scale Model ◽  
Test Technique ◽  
Turbine Blade Cooling ◽  
Turbine Cooling ◽  
Impingement Heat Transfer ◽  
Large Scale Model

Impingement channels are often used in turbine blade cooling configurations. This paper examines the heat transfer performance of a typical integrally cast impingement channel. Detailed heat transfer coefficient distributions on all heat transfer surfaces were obtained in a series of low temperature experiments carried out in a large-scale model of a turbine cooling system using liquid crystal techniques. All experiments were performed on a model of a 19-hole, low aspect ratio impingement channel. The effect of flow introduced at the inlet to the channel on the impingement heat transfer within the channel was investigated. A novel test technique has been applied to determine the effect of the initial cross flow on jet penetration. The experiments were performed at an engine representative Reynolds number of 20,000 and examined the effect of additional initial cross flow up to 10% of the total mass flow.

scholarly journals Heat Transfer Enhancement Within a Turbine Blade Cooling Passage Using Ribs and Combinations of Ribs With Film Cooling Holes

1994 ◽  
Author(s):  
J. R. Shen ◽  
Z. Wang ◽  
P. T. Ireland ◽  
T. V. Jones ◽  
A. R. Byerley
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Liquid Crystals ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Scale Model ◽  
Surface Shear Stress ◽  
Surface Shear ◽  
Cooling Passage ◽  
Film Cooling Holes

A transient heat transfer method which uses liquid crystals has been applied to a scale model of a turbine rotor blade passage. Detailed contours of local heat transfer coefficient are presented for the passage in which the heat transfer to one wall was enhanced firstly by ribs and then with ribs combined with holes. The hole geometry and experimental dimensionless flow rates were representative of those occurring at the entrance to engine film cooling holes. The results for the ribbed passage are compared to established correlations for developed flow. Qualitative surface shear stress distributions were determined with liquid crystals. The complex distributions of heat transfer coefficient are discussed in the light of the interpreted flow field.

Heat Transfer Enhancement Within a Turbine Blade Cooling Passage Using Ribs and Combinations of Ribs With Film Cooling Holes

1996 ◽  
Vol 118 (3) ◽  
pp. 428-434 ◽  
Author(s):  
J. R. Shen ◽  
Z. Wang ◽  
P. T. Ireland ◽  
T. V. Jones ◽  
A. R. Byerley
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Liquid Crystals ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Scale Model ◽  
Surface Shear Stress ◽  
Surface Shear ◽  
Cooling Passage ◽  
Film Cooling Holes

A transient heat transfer method using liquid crystals has been applied to a scale model of a turbine rotor blade passage. Detailed contours of local heat transfer coefficient are presented for the passage in which the heat transfer to one wall was enhanced first by ribs and then with ribs combined with holes. The hole geometry and experimental dimensionless flow rates were representative of those occurring at the entrance to engine film cooling holes. The results for the ribbed passage are compared to established correlations for developed flow. Qualitative surface shear stress distributions were determined with liquid crystals. The complex distributions of heat transfer coefficient are discussed in light of the interpreted flow field.

Experimental Investigation on the Heat Transfer of a Leading Edge Impingement Cooling System for Low Pressure Turbine Vanes

2010 ◽  
Vol 132 (12) ◽  
Author(s):  
Pedro de la Calzada ◽  
Jose Javier Alvarez
Keyword(s):  
Heat Transfer ◽  
Liquid Crystal ◽  
Cooling System ◽  
Leading Edge ◽  
Good Resolution ◽  
Stagnation Line ◽  
Impingement Cooling ◽  
Area Of Interest ◽  
Turbine Vanes ◽  
Flow Features

Impingement cooling through jet holes is a very attractive cooling system for heat rejection at high heat loaded areas as the leading edge of turbine vanes. Although some correlations and tools are available to dimension such systems, the variety and complexity of the flow features present in those systems still require experimental validation of real engine designs. Among the experimental techniques possible to be used, transient liquid crystal method offers good resolution as well as sufficient accuracy. Under this investigation, an impingement cooling system for the leading edge of a contrarotating power turbine (PT) representative of a small turboshaft engine was investigated experimentally. The PT vane features a very thin leading edge with high curvature and side channels rapidly turning backward. Constraints on cooling flow consumption and distribution led to a leading edge configuration with two rows of staggered jets. This particular configuration was experimentally investigated for three different Reynolds numbers around the design point by using a transient liquid crystal technique, which allows the measurement of surface distribution of heat transfer coefficient at the area of interest. Heat transfer results are presented in terms of surface distributions, impingement rows stagnation line local distributions, streamwise distributions along planes over the impingement stagnation points, span averaged streamwise local distributions, and surface averaged values. These results are then compared with available correlations from existing literature showing good matching for both maximum and averaged values. The results are also used as baseline data to discuss some of the flow features that can have effect on the heat transfer on this particular configuration.

The Effect of Impingement Jet Heat Transfer on Casing Contraction in a Turbine Case Cooling System

2014 ◽  
Author(s):  
Orpheas Tapanlis ◽  
Myeonggeun Choi ◽  
David R. H. Gillespie ◽  
Leo V. Lewis ◽  
Carlo Ciccomascolo
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Flow Field ◽  
Transfer Coefficient ◽  
Large Scale ◽  
Cooling System ◽  
Impinging Jets ◽  
Tip Clearance ◽  
Scale Model ◽  
Number Range

This paper reports full local Nusselt number distributions under an array of impinging jets typical of those used for thermal tip clearance control through casing contraction. Characteristic features of this type of application are sparse arrays of short cooling holes flowing at low jet Reynolds numbers (700–11,000) and large stand-off distances from the surface into a semi-confined passage with multiple exits. These features are captured in a large scale model, approximately ten times engine scale. Heat transfer measurements are made using the transient thermochromic liquid crystal technique. The measurement domain was extended far downstream of the impingement array. This allowed the entire heat transfer coefficient distribution contributing to the contraction of the liner around the rotor blades to be captured. CFD studies were conducted to characterize the flow field obtained, which in turn is helpful in understanding the drivers of heat transfer. The results are compared to existing industry standard correlations, which are generally outside the geometric and Reynolds number range of interest. It was shown that, for the tested geometries, the heat transfer was sensibly unaffected by whether the flow was exhausted through one side of the exit passage or equally in both directions, and the bulk flow field could be predicted using a modified distributed injection model. The heat transfer coefficient distributions are linked to a thermal-mechanical finite element model to provide thermal boundary conditions on an idealized representation of the casing for casing contraction in the presence of cooling scheme. For one of the geometries tested, data from an engine casing thermocouple survey have been compared to predictions of casing temperature determined using the measured heat transfer coefficient distributions and these show reasonable agreement.

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.

Effect of an Oscillating Flow Direction on Leading Edge Heat Transfer

1984 ◽  
Vol 106 (1) ◽  
pp. 222-228 ◽  
Author(s):  
M. L. Marziale ◽  
R. E. Mayle
Keyword(s):  
Heat Transfer ◽  
Strouhal Number ◽  
Large Scale ◽  
Flow Direction ◽  
Leading Edge ◽  
Periodic Variation ◽  
Scale Model ◽  
Transfer Rates ◽  
Large Scale Model ◽  
Turbulence Length

An experimental investigation was conducted to examine the effect of a periodic variation in the angle of attack on heat transfer at the leading edge of a gas turbine blade. A circular cylinder was used as a large-scale model of the leading edge region. The cylinder was placed in a wind tunnel and was oscillated rotationally about its axis. The incident flow Reynolds number and the Strouhal number of oscillation were chosen to model an actual turbine condition. Incident turbulence levels up to 4.9 percent were produced by grids placed upstream of the cylinder. The transfer rate was measured using a mass transfer technique and heat transfer rates inferred from the results. A direct comparison of the unsteady and steady results indicate that the effect is dependent on the Strouhal number, turbulence level, and the turbulence length scale, but that the largest observed effect was only a 10 percent augmentation at the nominal stagnation position.

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