Impingement Heat Transfer Coefficients Research Articles

Development of Experimental and Numerical Methods for the Analysis of Active Clearance Control Systems1

Abstract The ever increasing performance requirements of modern aeroengines necessitate the development of effective ways to improve efficiency and reduce losses. Casing temperature control is particularly critical from this point of view, since thermal expansion directly affects the blade tip clearance and thus the associated leakages. To limit the turbine tip flows, active clearance control (ACC) systems have been implemented over the last decades. These systems are usually based upon impingement cooling, generated by a series of perforated manifolds enclosing the turbine casing. When dealing with aeroengine low pressure turbines, the current trend in increasing the engine bypass ratio, so as to enhance the system propulsive efficiency, pushes the limits of ACC traditional design performance. The reduction of the pressure head at the ACC system inlet requires lower nozzle-to-target distances as well as denser impingement arrays to compensate the reduction of the jets' Reynolds number. Literature correlations for the impingement heat transfer coefficient estimation are then out of their confidence range and also RANS numerical approaches appear not suitable for future ACC designs. In this work, methodologies for the development of accurate and reliable tools to determine the heat transfer characteristics of low pressure ACC systems are presented. More precisely, this paper describes a custom designed finite difference procedure capable of solving the inverse conduction problem on the target plate of a test sample. The methodology was successfully applied to an experimental setup for the measurement of the thermal loads on a target plate of a representative low pressure ACC impinging system. The experimental outcomes are then used to validate a suitable numerical approach. Results show that RANS model is not able to mimic the experimental trends, while scale-resolving turbulence models provide a good reconstruction of the experimental evidences, thus allowing to obtain a correct interpretation of flow and thermal phenomena for ACC systems.

Detailed Flow and Heat Transfer Analyses in a Rib-Roughened Trailing-Edge Cooling Cavity With Impingement

A rig, simulating two adjacent cooling cavities on the trailing side of an airfoil, made up of two trapezoidal channels is tested. Eleven crossover holes on the partition wall between the two channels create the jets. Two exit flow arrangements are investigated—(a) jets, after interaction with the target surface, are turned toward the target channel exit axially and (b) jets exit from a row of racetrack-shaped slots along the target channel. Flow measurements are reported for individual holes and heat transfer coefficients on the eleven target walls downstream the jets are measured using liquid crystals under steady-state conditions. Smooth as well as ribbed target surfaces with four rib angles are tested. Correlations are developed for mass flow rate through each crossover hole, varying the number of crossover holes. Heat transfer coefficient variations along the target channel are reported for a range of 5000–50,000 local jet Reynolds numbers. Major conclusions are: (1) Correlations are developed to successfully predict the air flow rate through each crossover hole for partition walls with six to eleven crossover holes, based on the pressure drop across the holes, (2) impingement heat transfer coefficient correlates well with local jet Reynolds number for both exit flow arrangements, and (3) case of target channel flow exiting from the channel end, at higher jet Reynolds numbers, produce higher heat transfer coefficients than those in the case of flow exiting through a row of slots along the target channel opposite to the crossover holes.

The influence of microjet array area ratio on heat transfer in the compact heat exchanger

The paper describes the comprehensive study on the effect of microjet array geometrical parameters on the heat transfer enhancement in the modular heat exchanger. The conducted experimental study provides an experimental database on single phase submerged microjet heat transfer. The Wilson plot method was applied to determine the heat transfer coefficients in the laminar and transition flow regimes of a liquid-to-liquid heat exchanger. The heat exchanger was capable of exchanging 296 W of thermal energy at LMTD of 44 K. The obtained heat transfer coefficient reaches over 24,000 W/m2 K.Average Nusselt number predictions of the Wen and Jang (2003) correlation were in best agreement with the experimentally determined average Nusselt numbers. In the whole tested flow range, Nusselt numbers were not well correlated by any of the correlations from the literature. The experimentally determined Nusselt numbers were significantly lower than expected, due to limited applicability of given literature correlations.The author also proposed own experimental correlation for jet impingement heat transfer coefficient, predicting the experimental results within 30%.

Turbine Blade Leading Edge Cooling With One Row of Normal or Tangential Impinging Jets

Jet impingement cooling has been extensively used in the leading edge region of a gas turbine blade. This study focuses on the effect of jet impinging position on leading edge heat transfer. The test model is composed of a semicylindrical target plate, side exit slots, and an impingement jet plate. A row of cylindrical injection holes is located along the axis (normal jet) or the edge (tangential jet) of the semicylinder, on the jet plate. The jet-to-target-plate distance to jet diameter ratio (z/d) is 5 and the ratio of jet-to-jet spacing to jet diameter (s/d) is 4. The jet Reynolds number is varied from 10,000 to 30,000. Detailed impingement heat transfer coefficient distributions were experimentally measured by using the transient liquid crystal (TLC) technique. To understand the thermal flow physics, numerical simulations were performed using Reynolds-averaged Navier–Stokes (RANS) with two turbulence models: realizable k–ε (RKE) and shear stress transport k–ω model (SST). Comparisons between the experimental and the numerical results are presented. The results indicate that the local Nusselt numbers on the test surface increase with the increasing jet Reynolds number. The tangential jets provide more uniform heat transfer distributions as compared with the normal jets. For the normal jet impingement and the tangential jet impingement, the RKE model provides better prediction than the SST model. The results can be useful for selecting a jet impinging position in order to provide the proper cooling distribution inside a turbine blade leading edge region.

Crossover Jet Impingement in a Rib-Roughened Trailing-Edge Cooling Channel

Airfoil trailing-edge cooling is the main focus of this study. The test section was made up of two adjacent trapezoidal channels, simulating the trailing-edge cooling cavity of a gas turbine airfoil and its neighboring cavity. Eleven racetrack-shaped holes were drilled on the partition wall between the two channels to produce 11 cross-over jets that impinged on the rib-roughened wall of the trailing-edge channel. The jets, after impinging on their respective target surface, turned toward the trailing-edge channel exit. Smooth target wall, as a baseline case, as well as four rib angles with the flow of 0 deg, 45 deg, 90 deg, and 135 deg are investigated. Cross-over holes axes were on the trailing-edge channel center plane, i.e., no tilting of the cross-over jets. Steady-state liquid crystal thermography technique was used in this study for a range of jet Reynolds number of 10,000–35,000. The test results are compared with the numerical results obtained from the Reynolds-averaged Navier–Stokes and energy equation. Closure was attained by k–ω with shear stress transport (SST) turbulence model. The entire test rig (supply and trailing-edge channels) was meshed with variable density hexagonal meshes. The numerical work was performed for boundary conditions identical to those of the tests. In addition to the impingement heat transfer coefficients, the numerical results provided the mass flow rates through individual cross-over holes. This study concluded that: (a) the local Nusselt numbers correlate well with the local jet Reynolds numbers, (b) 90 deg rib arrangement, that is, when the cross-over jet axis was parallel to the rib longitudinal axis, produced higher heat transfer coefficients, compared to other rib angles, and (c) numerical heat transfer results were generally in good agreement with the test results. The overall difference between the computational fluid dynamics (CFD) and test results was about 10%.

Effect of jet length and ambient temperature on the performance of a two-phase jet impingement heat sink refrigeration system

The jet impingement heat sink integrated with a compact oil-free R-134a vapor compression refrigeration system introduced in a previous work (Oliveira and Barbosa, 2017) is now further evaluated in terms of the influence of the compressor piston stroke, applied thermal load, orifice-to-heater distance (jet length) and ambient (hot end) temperature. The proposed heat sink is a compact active thermal solution for concentrated heat loads because it integrates the evaporator and the expansion device into a single unit, making use of a single two-phase impinging jet as the cooling mechanism. The present analysis is based on the coefficient of performance and other steady-state heat transfer parameters associated with the impinging jet (heat transfer coefficient and heater surface temperature). A reduction of the jet length promoted a more vigorous splattering of the jet on the heated surface, enhancing the droplet breakup, which in turn reduced significantly the critical heat flux. An increase of the hot reservoir temperature increased the jet impingement heat transfer coefficient.

Novel two-phase jet impingement heat sink for active cooling of electronic devices

This work presents a compact vapor compression cooling system equipped with a small-scale oil-free R-134a compressor and a jet-impingement-based heat sink that integrates the evaporator and the expansion device into a single unit. At the present stage of the development, a single orifice was used to generate the high-speed two-phase impinging jet on the heated surface. The effects of the compressor piston stroke, applied thermal load and orifice diameter on the system performance were quantified. The thermodynamic performance of the system was evaluated in terms of the temperature of the heated surface, impinging jet heat transfer coefficient, several system thermal resistances, coefficient of performance, second-law efficiency and second-law ratio. The coefficient of performance of the new refrigeration system increased with the cooling capacity, justifying its application in the removal of large thermal loads. The maximum system cooling capacity with a single jet was approximately 160W, which was achieved with an orifice diameter of 500μm and operation at a full compressor piston stroke. This condition corresponded to a COP of 2.3, a second-law efficiency of 8.0%, a jet impingement heat transfer coefficient above 15kWm−2K−1 and a heater surface temperature of approximately 30°C.

Experimental Investigation of Local and Average Heat Transfer Coefficients Under an Inline Impinging Jet Array, Including Jets With Low Impingement Distance and Inclined Angle

Comprehensive impingement heat transfer coefficients data are presented with varied Reynolds number, hole spacing, jet-to-target distance, and hole inclination utilizing transient liquid crystal. The impingement configurations include: streamwise and spanwise jet-to-jet spacing (X/D, Y/D) are 4∼8 and jet-to-target plate distance (Z/D) is 0.75∼3, which composed a test matrix of 36 different geometries. The Reynolds numbers vary between 5,000 and 25,000. Additionally, hole inclination pointing to the upstream direction (θ: 0 deg∼40 deg) is also investigated to compare with normal impingement jets. Local and averaged heat transfer coefficients data are presented to illustrate that (1) surface Nusselt numbers increase with streamwise development for low impingement distance, while decrease for large impingement distance. The increase or decrease variations are also influenced by Reynolds number, streamwise and spanwise spacings. (2) Nusselt numbers of impingement jets with inclined angle are similar to those of normal impingement jets. Due to the increase or decrease variations corresponding to small or large impingement distance, a two-regime-based correlation, based on that of Florschuetz et al., is developed to predict row-averaged Nusselt number. The new correlation is capable to cover low Z/D∼0.75 and presents better prediction of row-averaged Nusselt number, which proves to be an effective impingement design tool.

Applicability of arrays of microjet heat transfer correlations to design compact heat exchangers

The article presents experimental studies on a compact heat exchanger with heat transfer intensification by means of impinging microjets. The pursuit to provide high performance of heat exchangers is a response to the demand both in economics and in the universal tendency to miniaturization of industrial equipment. This paper presents the design and tests of a prototype, microjet heat exchanger. The modular design of the heat exchanger allows to change its geometrical dimensions, as well as changing the heat exchange membrane material. The study of heat transfer in water–water flow allows to determine the heat transfer efficiency, the characteristics of heat transfer, and the heat transfer coefficient values. Data were collected for the pressure drops in heat exchanger not exceeding 15 kPa, i.e. such as in conventional heat exchangers. Hydraulic characteristics of a model heat exchanger were obtained. Experimental values of heat transfer for jet impingement were calculated by means of Wilson's plot method. Obtained values of heat transfer coefficient were compared with literature correlations. Authors also proposed their own empirical correlation for jet impingement heat transfer coefficient.

Conjugate heat transfer analysis of the effects of impingement channel height for a turbine blade endwall

Advancements in cooling for applications such as gas turbines components require improved understanding of the complex heat transfer mechanisms and the interactions between those mechanisms. Critical cooling applications often rely on multiple thermal protection techniques, including internal cooling and external film cooling in gas turbine airfoils, to efficiently cool components and limit the use of coolant. Most research to quantify the effectiveness of such cooling technologies for gas turbine applications has isolated internal and external cooling in separate experiments. The research presented in this paper uses a conjugate heat transfer approach to account for the combined effects of both internal and external cooling. The geometry used for this study is a turbine blade endwall that includes impingement and film cooling as well as the relevant conduction through the endwall. Appropriate geometric and flow parameters were scaled to ensure engine relevant dimensionless temperatures were obtained. Using the conjugate heat transfer approach, the effect of varying the height of the impingement channel was examined using spatially resolved external wall temperatures obtained from both experiments and simulations. A one-dimensional heat transfer analysis was used to derive the average internal heat transfer coefficients from the experimental results. Both experiments and simulations showed good agreement between area averaged cooling effectiveness and impingement heat transfer coefficients. The cooling effectiveness and heat transfer coefficients peaked for an impingement channel height of around three impingement hole diameters. However, the heat transfer coefficients were more sensitive than the overall effectiveness to the changes in height of the impingement channel.

Heat transfer performance of Cu–water nanofluids in the jet arrays impingement cooling system

In this study, nanofluids were introduced into jet arrays impingement as the working fluid. The heat transfer features of the nanofluids were experimentally investigated. Four different Cu-nanoparticle volume fractions ranged from 0.17 Vol.% to 0.64 Vol.% and two dispersant sodium dodecyl benzoic sulfate (SDBS) mass concentrations varied from 0.05 wt% to 0.1 wt% were involved. The influences of the nanoparticle volume fraction and the dispersant SDBS on the heat transfer of nanofluids were discussed. The experimental results show that the suspended nanoparticles increase the heat transfer performances of the jet arrays impingement cooling system. It had also been found that compared with the case of using nanofluids without any addition of dispersant, the nanofluid with dispersant led to a great deterioration on impingement heat transfer coefficient and even the heat transfer coefficients were smaller than that of the base liquid.

Experimental and Numerical Crossover Jet Impingement in a Rib-Roughened Airfoil Trailing-Edge Cooling Channel

Local and average heat transfer coefficients were measured in a test section simulating a rib-roughened trailing edge cooling cavity of a turbine airfoil. The test rig was made up of two adjacent channels, each with a trapezoidal cross sectional area. The first channel, simulating the cooling cavity adjacent to the trailing-edge cavity, supplied the cooling air to the trailing-edge channel through a row of racetrack-shaped slots on the partition wall between the two channels. Eleven crossover jets, issued from these slots entered the trailing-edge channel, impinged on eleven radial ribs and exited from a second row of race-track shaped slots on the opposite wall in staggered or inline arrangement. Two jet angles of 0 deg and 5 deg and a range of jet Reynolds number from 10,000 to 35,000 were tested and compared. The numerical models contained the entire trailing-edge and supply channels with all slots and ribs to simulate exactly the tested geometries. They were meshed with all-hexa structured mesh of high near-wall concentration. A pressure-correction based, multiblock, multigrid, unstructured/adaptive commercial software was used in this investigation. The realizable k-ε turbulence model was employed in combination with an enhanced wall treatment approach for the near wall regions. Boundary conditions identical to those of the experiments were applied and several turbulence model results were compared. The numerical analyses also provided the share of each crossover and each exit hole from the total flow for different geometries. The major conclusions of this study were: (a) except for the first and last cross-flow jets, which had different flow structures, other jets produced the same heat transfer results on their target surfaces; (b) tilted crossover jets produced higher heat transfer coefficients on the target surface towards which they were tilted and lower values on the opposite surface, and (c) the numerical predictions of impingement heat transfer coefficients were in good agreement with the measured values for most cases thus CFD could be considered a viable tool in airfoil cooling circuit designs.

Thermocouple thermal inertia effects on impingement heat transfer experiments using the transient liquid crystal technique

The transient liquid crystal technique is widely used for impingement heat transfer experiments. Additionally, due to the difficulty of producing pure temperature steps in the flow, many authors assumed the fluid temperature evolution as a series of step changes using Duhamel's superposition theorem. However, for small impingement configurations where the jets are fed from the same plenum chamber, and hence flow velocities are relatively small, thermal inertia of commercial thermocouples causes a delay, lagging from the real plenum temperature history. This paper investigates thermal inertia characteristics of thermocouples and their effect on the calculation of impingement heat transfer coefficient. Several thermocouples with exposed junction and different wire diameter were considered over a range of plenum flow conditions typically found in impingement heat transfer experiments. The effect of thermocouple time constant on the evaluation of the heat transfer rate was investigated in a narrow channel consisting of five inline impingement jets. The results indicated a significant effect of thermocouple response on the stagnation point region heat transfer, while lower local heat transfer rates are negligibly affected as liquid crystal signals appear later in time and the driving gas temperature history has a smaller influence on the evaluated data.

Experimental and Numerical Cross-Over Jet Impingement in an Airfoil Trailing-Edge Cooling Channel

Trailing edge cooling cavities in modern gas turbine airfoils play an important role in maintaining the trailing-edge temperature at levels consistent with airfoil design life. In this study, local and average heat transfer coefficients were measured in a test section, simulating the trailing-edge cooling cavity of a turbine airfoil using the steady-state liquid crystal technique. The test rig was made up of two adjacent channels, each with a trapezoidal cross-sectional area. The first channel, simulating the cooling cavity adjacent to the trailing-edge cavity, supplied the cooling air to the trailing-edge channel through a row of racetrack-shaped slots on the partition wall between the two channels. Eleven crossover jets issued from these slots entered the trailing-edge channel and exited from a second row of race-track shaped slots on the opposite wall in staggered or inline arrangement. Two jet angles were examined. The baseline tests were for zero angle between the jet axis and the trailing-edge channel centerline. The jets were then tilted toward one wall (pressure or suction side) of the trailing-edge channel by 5 deg. Results of the two set of tests for a range of local jet Reynolds number from 10,000 to 35,000 were compared. The numerical models contained the entire trailing-edge and supply channels with all slots to simulate exactly the tested geometries. They were meshed with all-hexa structured mesh of high near-wall concentration. A pressure-correction based, multiblock, multigrid, unstructured/adaptive commercial software was used in this investigation. Standard high Reynolds number k−ε turbulence model in conjunction with the generalized wall function for most parts was used for turbulence closure. Boundary conditions identical to those of the experiments were applied and several turbulence model results were compared. The numerical analyses also provided the share of each cross-over and each exit hole from the total flow for different geometries. The major conclusions of this study were (a) except for the first and last cross-flow jets which had different flow structures, other jets produced the same heat transfer results on their target surfaces, (b) jets tilted at an angle of 5 deg produced higher heat transfer coefficients on the target surface. The tilted jets also produced the same level of heat transfer coefficients on the wall opposite the target wall, and (c) the numerical predictions of impingement heat transfer coefficients were in good agreement with the measured values for most cases; thus, computational fluid dynamics could be considered a viable tool in airfoil cooling circuit designs.

An Experimental and Numerical Investigation of Impingement Heat Transfer in Airfoils Leading-Edge Cooling Channel

To enhance the heat transfer coefficient along the leading edge of an airfoil, the cooling flow enters the leading edge cavity from the adjacent cavity through a series of crossover holes, cast on the partition wall between the two cavities. The crossover jets impinge on the leading-edge wall, then form a crossflow that moves towards the airfoil tip. In this experimental setup, there were nine crossover holes with racetrack-shaped cross sections on the partition wall. To investigate the effects of crossflow created by the upstream jets on the flow through each hole and on the impingement heat transfer coefficients, five crossover flow arrangements were studied. These flow arrangements were for 0, 1, 2, 3, and 4 jets upstream of the crossover hole # 5 for which the impingement heat transfer coefficients were measured. Jet to target wall distance ratio, Z/Dh, of 2.81 and local jet Reynolds numbers ranging from 7000 to 32,000 were tested. All tested geometries were meshed with all-hexa structured mesh of high near-wall concentration. Boundary conditions identical to those of experiments were applied and several turbulence model results were compared. The major conclusions of this study were: a) the crossflow produced by the upstream jets caused a slight reduction in impingemen heat transfer coefficients, b) there could be a significant variation in mass flow rate through the crossover holes, and c) the numerical predictions using the standard high Reynolds number k−ε turbulence model along with the generalized wall function, were in good agreement with the measured values for most cases, thus CFD could be considered a viable tool in airfoil cooling circuit designs.

Experimental and Numerical Study of Impingement on an Airfoil Leading Edge With and Without Showerhead and Gill Film Holes

This experimental investigation deals with impingement on the leading edge of an airfoil with and without showerhead film holes and its effects on heat transfer coefficients on the airfoil nose area as well as the pressure and suction side areas. a comparison between the experimental and numerical results are also made. the tests were run for a range of flow conditions pertinent to common practice and at an elevated range of jet Reynolds numbers (8000–48,000). The major conclusions of this study were: (a) The presence of showerhead film holes along the leading edge enhances the internal impingement heat transfer coefficients significantly, and (b) while the numerical predictions of impingement heat transfer coefficients for the no-showerhead case were in good agreement with the measured values, the case with showerhead flow was under-predicted by as much as 30% indicating a need for a more elaborate turbulence modeling.

Condensing-convective boundary conditions in moist air impingement ovens

Previously developed equations for impingement heat transfer coefficients experienced by a flat plate under an array of slot nozzles were compared to values measured for discrete model food products in a commercial moist air impingement oven. The best correlation predicted the convective heat transfer coefficients to an average absolute error of 1.9%, with a standard error of prediction (SEP) of 1.9 W/m 2 K, when accounting for edge effects. Condensation heat transfer was successfully modeled as a convective mass transfer phenomenon. The analogous nature between heat and mass transfer was used to predict the mass transfer coefficients from correlations for convective heat transfer. The same correlation found to most accurately predict the convective heat transfer coefficient also most accurately predicted the mass transfer coefficient for impingement flow. When accounting for edge effects, the model predicted the mass transfer coefficient to an average absolute error of 12.7%, with an SEP of 16.4 mm/s.

Influence of Impingement Temperature and Nozzle Geometry on Heat Transfer—Experimental and Theoretical Analysis

Based on the earlier studies the most common empirical correlations in the literature predict the impingement heat transfer coefficients rather well at low (close to 100°C) temperatures, but get inaccurate at higher temperatures. Impingement temperatures used in paper drying applications are typically 300 to 700°C, and there has been a need to improve the existing heat transfer correlations at high temperature area. This study presents experimental results of impingement heat transfer measurements with a laboratory-scale heat transfer test rig. Five nozzle configurations were measured. The parameters varied in the investigation were nozzle-to-plate distance, nozzle open area, nozzle diameter, impingement velocity and impingement air temperature. Regression model of heat transfer was developed based on the measurement data. A correction factor including the impingement and heat receiving surface temperatures is proposed. The correction factor can be used to improve the existing correlations at large jet to heat receiving surface temperature differences.

Experimental and Numerical Investigation of Impingement on a Rib-Roughened Leading-Edge Wall

Effective cooling of the airfoil leading edge is imperative in gas turbine designs. Among several methods of cooling the leading edge, impingement cooling has been utilized in many modern designs. In this method, the cooling air enters the leading edge cavity from the adjacent cavity through a series of crossover holes on the partition wall between the two cavities. The crossover jets impinge on a smooth leading-edge wall and exit through the film holes, and, in some cases, form a cross flow in the leading-edge cavity and move toward the end of the cavity. It was the main objective of this investigation to measure the heat transfer coefficient on a smooth as well as rib-roughened leading-edge wall. Experimental data for impingement on a leading-edge surface roughened with different conical bumps and radial ribs have been reported by the same authors previously. This investigation, however, deals with impingement on different horseshoe ribs and makes a comparison between the experimental and numerical results. Three geometries representing the leading-edge cooling cavity of a modern gas turbine airfoil with crossover jets impinging on (1) a smooth wall, (2) a wall roughened with horseshoe ribs, and (3) a wall roughened with notched-horseshoe ribs were investigated. The tests were run for a range of flow arrangements and jet Reynolds numbers. The major conclusions of this study were: (a) Impingement on the smooth target surface produced the highest overall heat transfer coefficients followed by the notched-horseshoe and horseshoe geometries. (b) There is, however, a heat transfer enhancement benefit in roughening the target surface. Among the three target surface geometries, the notched-horseshoe ribs produced the highest heat removal from the target surface, which was attributed entirely to the area increase of the target surface. (c) CFD could be considered as a viable tool for the prediction of impingement heat transfer coefficients on an airfoil leading-edge wall.

INVESTIGATION OF IMPINGEMENT HEAT TRANSFER COEFFICIENT AT HIGH TEMPERATURES

ABSTRACT Very little information exists for the impingement heat transfer coefficient at high temperatures. All available empirical correlations are mainly based on experiments conducted at relatively low impingement temperatures, and thus cannot describe the heat transfer characteristics of the impingement air at high temperatures with sufficient accuracy. A comprehensive study of the impingement heat transfer coefficient at high temperatures is carried out and presented in this paper. The aim of the study is to give a summary of the experimental results of the impingement heat transfer covering a large impingement air temperature range from 100 to 700°C. Heat transfer measurements were carried out on a laboratory-scale test rig. The main parts of the rig were a fan, a gas burner for air heating, a heavily insulated nozzle array with 300 × 500 mm impingement surface, a 40 mm thick and 300 × 500 mm sized aluminium plate for determination of heat transfer, and a data acquisition system. The heat transfer rate was determined from the heat-up rate of the aluminium plate due to the high temperature jet impingement.