Experimental and Theoretical Investigation of Thermal Effectiveness in Multi-Perforated Plates for Combustor Liner Effusion Cooling

2013 ◽  
Author(s):  
Antonio Andreini ◽  
Bruno Facchini ◽  
Alessio Picchi ◽  
Lorenzo Tarchi ◽  
Fabio Turrini
Keyword(s):  
Film Cooling ◽  
Cooling System ◽  
Fluid Dynamic ◽  
Heat Removal ◽  
Perforated Plates ◽  
Correlative Analysis ◽  
Pattern Shape ◽  
The Impact ◽  
Combustor Liner ◽  
Overall Effectiveness

State-of-the-art liner cooling technology for modern combustors is represented by effusion cooling (or full-coverage film cooling). Effusion is a very efficient cooling strategy based on the use of multi-perforated liners, where metal temperature is lowered by the combined protective effect of coolant film and heat removal through forced convection inside each hole. The aim of this experimental campaign is the evaluation of the thermal performance of multi-perforated liners with geometrical and fluid-dynamic parameters ranging among typical combustor engine values. Results were obtained as adiabatic film effectiveness following the mass transfer analogy by the use of Pressure Sensitive Paint, while local values of overall effectiveness were obtained by eight thermocouples housed in as many dead holes about 2 mm below the investigated surface. Concerning the tested geometries, different porosity levels were considered: such values were obtained both increasing the hole diameter and pattern spacing. Then the effect of hole inclination and aspect ratio pattern shape were tested to assess the impact of typical cooling system features. Seven multi perforated planar plates, reproducing the effusion arrays of real combustor liners, were tested imposing 6 blowing ratios in the range 0.5–5. Test samples were made of stainless steel (AISI304) in order to achieve Biot number similitude for overall effectiveness tests. To extend the validity of the survey a correlative analysis was performed to point out, in an indirect way, the augmentation of hot side heat transfer coefficient due to effusion jets. Finally, to address the thermal behaviour of the different geometries in presence of gas side radiation, additional simulations were performed considering different levels of radiative heat flux.

Experimental and Theoretical Investigation of Thermal Effectiveness in Multiperforated Plates for Combustor Liner Effusion Cooling

2014 ◽  
Vol 136 (9) ◽  
Author(s):  
Antonio Andreini ◽  
Bruno Facchini ◽  
Alessio Picchi ◽  
Lorenzo Tarchi ◽  
Fabio Turrini
Keyword(s):  
Film Cooling ◽  
Cooling System ◽  
Fluid Dynamic ◽  
Density Ratio ◽  
Heat Removal ◽  
Correlative Analysis ◽  
Pattern Shape ◽  
The Impact ◽  
Combustor Liner ◽  
Overall Effectiveness

State-of-the-art liner cooling technology for modern combustors is represented by effusion cooling (or full-coverage film cooling). Effusion is a very efficient cooling strategy based on the use of multiperforated liners, where the metal temperature is lowered by the combined protective effect of the coolant film and heat removal through forced convection inside each hole. The aim of this experimental campaign is the evaluation of the thermal performance of multiperforated liners with geometrical and fluid-dynamic parameters ranging among typical combustor engine values. Results were obtained as the adiabatic film effectiveness following the mass transfer analogy by the use of pressure sensitive paint, while the local values of the overall effectiveness were obtained by eight thermocouples housed in as many dead holes about 2 mm below the investigated surface. Concerning the tested geometries, different porosity levels were considered: such values were obtained by both increasing the hole diameter and pattern spacing. Then the effect of the hole inclination and aspect ratio pattern shape were tested to assess the impact of typical cooling system features. Seven multiperforated planar plates, reproducing the effusion arrays of real combustor liners, were tested, imposing six blowing ratios in the range 0.5–5. Additional experiments were performed in order to explore the effect of the density ratio (DR=1;1.5) on the film effectiveness. Test samples were made of stainless steel (AISI304) in order to achieve the Biot number similitude for the overall effectiveness tests. To extend the validity of the survey a correlative analysis was performed to point out, in an indirect way, the augmentation of the hot side heat transfer coefficient due to effusion jets. Finallyv,in order to address the thermal behavior of the different geometries in the presence of gas side radiation, additional simulations were performed considering different levels of radiative heat flux.

Account of Film Turbulence for Predicting Film Cooling Effectiveness in Gas Turbine Combustors

1979 ◽  
Author(s):  
G. J. Sturgess
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Cooling Effectiveness ◽  
Turbine Engine ◽  
Film Cooling Effectiveness ◽  
Wide Range ◽  
Engine Combustion ◽  
Turbulence Effects ◽  
The Impact ◽  
Combustor Liner

The paper deals with a small but important part of the overall gas turbine engine combustion system and continues earlier published work on turbulence effects in film cooling to cover the case of film turbulence. Film cooling of the gas turbine combustor liner imposes certain geometric limitations on the coolant injection device. The impact of practical film injection geometry on the cooling is one of increased rates of film decay when compared to the performance from idealized injection geometries at similar injection conditions. It is important to combustor durability and life estimation to be able to predict accurately the performance obtainable from a given practical slot. The coolant film is modeled as three distinct regions, and the effects of injection slot geometry on the development of each region are described in terms of film turbulence intensity and initial circumferential non-uniformity of the injected coolant. The concept of the well-designed slot is introduced and film effectiveness is shown to be dependent on it. Only slots which can be described as well-designed are of interest in practical equipment design. A prediction procedure is provided for well-designed slots which describes growth of the film downstream of the first of the three film regions. Comparisons of predictions with measured data are made for several very different well-designed slots over a relatively wide range of injection conditions, and good agreement is shown.

Experimental Analysis of Different Coolants Used in Plasma Cutting Operation for the Improved Electrode Life

2015 ◽  
Vol 719-720 ◽  
pp. 46-49 ◽  
Author(s):  
Ginka Ranga Janardhana ◽  
Mani Senthil Kumar ◽  
B. Dhanasekar
Keyword(s):  
Temperature Rise ◽  
Metal Cutting ◽  
Cooling System ◽  
Heat Removal ◽  
Plasma Cutting ◽  
Life Test ◽  
Flow Rates ◽  
Optimal Flow ◽  
Cutting Operation ◽  
The Impact

The plasma cutting technology has been emerged as a developing technology which finds tremendous potential in fabrication and metal cutting industries. Thus for the cutting operation, the electrode inside the plasma torch plays a vital role for the plasma arc generation. The temperature of the arc is very high and at the electrode is around 3500°C. The cutting torch requires proper cooling system in order to prevent the electrode from quick wear due to the existence of high thermal gradient. The presented work aimed to study the impact of three coolants propylene glycol, ethylene glycol and de-ionized water flow over the electrode life. The experimental setups were arranged to study the heat transfer capabilities of the three coolants for different flow values and aimed to achieve the optimal flow rates for the efficient heat removal. The electrode life test trials were conducted to measure the electrode life for the flow values of three coolants in the temperature rise test. The optimal flow rates arrived from temperature rise test and the electrode life measured from life test are compared for the three coolant cases considered.

Overall Effectiveness of a Blade Endwall With Jet Impingement and Film Cooling

2013 ◽  
Vol 136 (3) ◽  
Author(s):  
Amy Mensch ◽  
Karen A. Thole
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Jet Impingement ◽  
Heat Transfer Analysis ◽  
Transfer Model ◽  
Convective Cooling ◽  
Impingement Cooling ◽  
Internal Impingement ◽  
The Impact ◽  
Overall Effectiveness

Ever-increasing thermal loads on gas turbine components require improved cooling schemes to extend component life. Engine designers often rely on multiple thermal protection techniques, including internal cooling and external film cooling. A conjugate heat transfer model for the endwall of a seven-blade cascade was developed to examine the impact of both convective cooling and solid conduction through the endwall. Appropriate parameters were scaled to ensure engine-relevant temperatures were reported. External film cooling and internal jet impingement cooling were tested separately and together for their combined effects. Experiments with only film cooling showed high effectiveness around film-cooling holes due to convective cooling within the holes. Internal impingement cooling provided more uniform effectiveness than film cooling, and impingement effectiveness improved markedly with increasing blowing ratio. Combining internal impingement and external film cooling produced overall effectiveness values as high as 0.4. A simplified, one-dimensional heat transfer analysis was used to develop a prediction of the combined overall effectiveness using results from impingement only and film cooling only cases. The analysis resulted in relatively good predictions, which served to reinforce the consistency of the experimental data.

scholarly journals Partial Redesign of an Accelerator Driven System Target for Optimizing the Heat Removal and Minimizing the Pressure Drops

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2090 ◽  
Author(s):  
Guglielmo Lomonaco ◽  
Giacomo Alessandroni ◽  
Walter Borreani
Keyword(s):  
Cooling System ◽  
Fluid Dynamic ◽  
Heat Removal ◽  
Dynamic Features ◽  
Pressure Drops ◽  
Driven System ◽  
Reference Design ◽  
Accelerator Driven Systems ◽  
Definition Of ◽  
Target Design

Accelerator Driven Systems (ADS) seem to be a good solution for safe nuclear waste transmutation. One of the most important challenges for this kind of machine is the target design, particularly for what concerning the target cooling system. In order to optimize this component a CFD-based approach has been chosen. After the definition of a reference design (Be target cooled by He), some parameters have been varied in order to optimize the thermal-fluid-dynamic features. The final optimized target design has an increased security margin for what regarding Be melting and reduces the maximum coolant velocity (and consequently even more the pressure drops).

Account of Film Turbulence for Predicting Film Cooling Effectiveness in Gas Turbine Combustors

1980 ◽  
Vol 102 (3) ◽  
pp. 524-534 ◽  
Author(s):  
G. J. Sturgess
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Cooling Effectiveness ◽  
Turbine Engine ◽  
Film Cooling Effectiveness ◽  
Wide Range ◽  
Engine Combustion ◽  
Turbulence Effects ◽  
The Impact ◽  
Combustor Liner

The paper deals with a small but important part of the overall gas turbine engine combustion system and continues earlier published work on turbulence effects in film cooling to cover the case of film turbulence. Film cooling of the gas turbine combustor liner imposes certain geometric limitations on the coolant injection device. The impact of practical film injection geometry on the cooling is one of increased rates of film decay when compared to the performance from idealized injection geometries at similar injection conditions. It is important to combustor durability and life estimation to be able to predict accurately the performance obtainable from a given practical slot. The coolant film is modeled as three distinct regions, and the effects of injection slot geometry on the development of each region are described in terms of film turbulence intensity and initial circumferential non-uniformity of the injected coolant. The concept of the well-designed slot is introduced and film effectiveness is shown to be dependent on it. Only slots which can be described as well-designed are of interest in practical equipment design. A prediction procedure is provided for well-designed slots which describes growth of the film downstream of the first of the three film regions. Comparisons of predictions with measured data are made for several very different well-designed slots over a relatively wide range of injection conditions, and good agreement is shown.

Numerical Analysis of Dilution Holes Deterioration Impacting the Performance of a V2500 Combustor

2020 ◽  
Author(s):  
Marco Konle ◽  
Ludovic de Guillebon ◽  
Lukas Schäflein
Keyword(s):  
Film Cooling ◽  
Operation Time ◽  
Test Cases ◽  
Air Jets ◽  
Individual Variations ◽  
Wide Range ◽  
Aero Engine ◽  
High Level ◽  
The Impact ◽  
Combustor Liner

Abstract In aero engine combustors, dilution air jets are used to additionally tailor the temperature field, the emissions, and the turbine inlet profile. These jets are entering the combustion chamber at different axial and circumferential locations through dedicated holes in the combustor liners. By deterioration, the diameters of these holes can significantly change over operation time. To evaluate the impact of such deterioration in the MRO context, the authors created a numerical model of a V2500 aero engine combustor and analyzed the impact. The data of dilution holes deterioration is based on the nominal design according the engine manual and the deviation measured for three engine combustors during maintenance inspection. The processes inside an aero engine combustor are very complex. To achieve most reliable information, a multi-physics approach was chosen for this evaluation. Validated in the past with a wide range of different academic test cases as well as industrial combustor test rigs, the evaluation allows conclusive analyses of the described deterioration. Back-to-back comparisons of individual variations reveals the most significant dilution holes row and give information about potential local shifts in combustor liner heat loads as well as in the exit profiles. Especially the distortion of the film cooling by the local interaction with the dilution jets could be observed. Since the deterioration of the dilution holes measured for the three combustors inspected is very small compared to the nominal design, the authors payed a lot of attention also on analyzing the model sensitivity. Increasing the spatial resolution, the plausibility of the numerical results were checked by analyzing the flow splits and the dilution jets penetration. The final step was the variation of the dilution holes individually and combined and the evaluation of resulting temperature distribution at the combustor liners and changes in the exit profile. Due to the fact that a multi-physics solver developed in the framework of OpenFOAM could be used, the authors could do these quite intensive CFD studies highly parallelized and, thus, in an acceptable time. The scalability of the solver reported already in former publications could be shown also in this application to the real engine combustor with a high level of complexity.

Analysis of Swirl number effects on effusion flow behaviour using time resolved PIV

2022 ◽  
pp. 1-33
Author(s):  
Tommaso Lenzi ◽  
Alessio Picchi ◽  
Antonio Andreini ◽  
Bruno Facchini
Keyword(s):  
Film Cooling ◽  
Cooling System ◽  
Tangential Velocity ◽  
Particle Image Velocimetry System ◽  
Swirl Number ◽  
Time Resolved ◽  
Experimental Apparatus ◽  
Turbulence Length ◽  
The Impact ◽  
Near Wall

Abstract The analysis of the interaction between the swirling and liner film-cooling flows is a fundamental task for the design of turbine combustion chambers since it influences different aspects such as emissions and cooling capability. Particularly, high turbulence values, flow instabilities, and tangential velocity components induced by the swirlers deeply affect the behavior of effusion cooling jets, demanding for dedicated time-resolved near-wall analysis. The experimental setup of this work consists of a non-reactive single-sector linear combustor test rig scaled up with respect to engine dimensions; the test section was equipped with an effusion plate with standard inclined cylindrical holes to simulate the liner cooling system. The rig was instrumented with a 2D Time-Resolved Particle Image Velocimetry system, focused on different field of views. The degree of swirl is usually characterized by the swirl number, Sn, defined as the ratio of the tangential momentum to axial momentum flux. To assess the impact of such parameter on the near-wall effusion behavior, a set of three axial swirlers with swirl number equal to Sn = 0.6 − 0.8 − 1.0 were designed and tested in the experimental apparatus. An analysis of the main flow by varying the Sn was first performed in terms of average velocity, RMS, and Tu values, providing kinetic energy spectra and turbulence length scale information. Following, the analysis was focused on the near-wall regions: the effects of Sn on the coolant jets was quantified in terms of vorticity analysis and jet oscillation.

Unsteady Effects on the Experimental Determination of Overall Effectiveness

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
James L. Rutledge ◽  
William P. Baker
Keyword(s):  
Biot Number ◽  
Film Cooling ◽  
Temperature Response ◽  
Engine Component ◽  
Turbine Component ◽  
Type Boundary ◽  
Unsteady Effects ◽  
The Impact ◽  
Overall Effectiveness

An increasingly common experimental method allows determination of the overall effectiveness of a film cooled turbine component. This method requires the Biot number of the experimental model to match that of the engine component such that the nondimensional surface temperature, ϕ, is matched to that of the engine component. The matched Biot number requirement effectively places a requirement on the thermal conductivity of the model and the traditional implementation places no requirement on the model's density or specific heat. However, such is not the case if such a model is exposed to unsteadiness in the flow such as with film cooling unsteadiness. In this paper, we develop an additional nondimensional parameter that must also be theoretically matched to conduct overall effectiveness experiments with unsteady film cooling. Since finding suitable materials with an acceptable combination of thermodynamic properties for a typical low temperature experiment can be difficult, simulations were conducted to determine the impact of imperfectly matched parameters achievable with common materials. Because the disparity between the diffusion and the unsteadiness time scales can hinder numerical simulation, a novel analytical solution to the heat equation with relevant unsteady Robin type boundary conditions is developed. Particular solutions are examined to determine the sensitivity of the temperature response of a turbine blade (or a model of one) to its material properties and the form of the unsteady variation in the convection parameters. It is shown that it is possible to obtain useful experimental results even with imperfectly matched parameters.

Experimental Investigation of the Flow Field and the Heat Transfer on a Scaled Cooled Combustor Liner With Realistic Swirling Flow Generated by a Lean-Burn Injection System

2014 ◽  
Author(s):  
Antonio Andreini ◽  
Gianluca Caciolli ◽  
Bruno Facchini ◽  
Alessio Picchi ◽  
Fabio Turrini
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Film Cooling ◽  
Swirling Flow ◽  
Injection System ◽  
Lean Burn ◽  
Real Geometry ◽  
Slot Film Cooling ◽  
The Impact ◽  
Combustor Liner

Lean burn swirl stabilized combustors represent the key technology to reduce NOx emissions in modern aircraft engines. The high amount of air admitted through a lean-burn injection system is characterized by very complex flow structures such as recirculations, vortex breakdown and processing vortex core, that may deeply interact in the near wall region of the combustor liner. This interaction and its effects on the local cooling performance make the design of the cooling systems very challenging, accounting for the design and commission of new test rigs for detailed analysis. The main purpose of the present work is the characterization of the flow field and the wall heat transfer due to the interaction of a swirling flow coming out from real geometry injectors and a slot cooling system which generates film cooling in the first part of the combustor liner. The experimental setup consists of a non-reactive three sector planar rig in an open loop wind tunnel; the rig, developed within the EU project LEMCOTEC, includes three swirlers, whose scaled geometry reproduces the real geometry of an Avio Aero PERM (Partially Evaporated and Rapid Mixing) injector technology, and a simple cooling scheme made up of a slot injection, reproducing the exhaust dome cooling mass flow. Test were carried out imposing realistic combustor operating conditions, especially in terms of reduced mass flow rate and pressure drop across the swirlers. The flow field is investigated by means of PIV, while the measurement of the heat transfer coefficient is performed through Thermochromic Liquid Crystals steady state technique. PIV results show the behavior of flow field generated by the injectors, their mutual interaction and the impact of the swirled main flow on the stability of the slot film cooling. TLC measurements, reported in terms of detailed 2D heat transfer coefficient maps, highlight the impact of the swirled flow and slot film cooling on wall heat transfer.

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