Cooling System Optimization of Combustor Liners

2017 ◽  
Author(s):  
Egidio Pucci ◽  
Matteo Cerutti ◽  
Guido Peano ◽  
Bruno Facchini ◽  
Antonio Andreini
Keyword(s):  
Heat Transfer ◽  
Cooling System ◽  
Thermal Strain ◽  
Strain Analysis ◽  
System Optimization ◽  
Optimization Process ◽  
Transfer Coefficients ◽  
Pressure Losses ◽  
Heat Transfer Coefficients ◽  
Data Matching

The optimization process of liner cooling system of industrial annular combustor is performed, since the early phase of design, by means of an innovative in house code, performing a one-dimensional conjugate aero-thermal-strain analysis. The liner cold side heat transfer coefficients in a turbulated forced convection region are iteratively computed updating metal and air temperatures and the deformed geometry of coolant passages from results of a heat balance. Coolant passages, in between the deformed surfaces of liner and baffle, influence the local velocity, changing heat transfer coefficients and coolant pressure losses. The liner and baffle strain computation has been validated comparing the code results with the ones obtained by a detailed finite element model. The correlations embedded in the code are calibrated thanks to a thermal and pressure data matching performed with experimental measurements acquired in a full annular rig test campaign. The optimization process, maintaining the same coolant pressure losses, minimizes the axial metal temperature gradients distribution, reducing the thermal induced stresses: the resulting liners durability can be significantly enhanced, without penalizing engine performance.

Heat Transfer Measurements in an Internal Cooling System Using a Transient Technique With Infrared Thermography

2012 ◽  
Author(s):  
Christian Egger ◽  
Jens von Wolfersdorf ◽  
Martin Schnieder
Keyword(s):  
Heat Transfer ◽  
Data Analysis ◽  
Infrared Thermography ◽  
Outer Surface ◽  
Cooling System ◽  
Internal Cooling ◽  
Test Model ◽  
Cooling Channel ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients

In this paper a transient method for measuring heat transfer coefficients in internal cooling systems using infrared thermography is applied. The experiments are performed with a two-pass internal cooling channel connected by a 180° bend. The leading edge and the trailing edge consist of trapezoidal and nearly rectangular cross sections, respectively, to achieve an engine-similar configuration. Within the channels rib arrangements are considered for heat transfer enhancement. The test model is made of metallic material. During the experiment the cooling channels are heated by the internal flow. The surface temperature response of the cooling channel walls is measured on the outer surface by infrared thermography. Additionally, fluid temperatures as well as fluid and solid properties are determined for the data analysis. The method for determining the distribution of internal heat transfer coefficients is based on a lumped capacitance approach which considers lateral conduction in the cooling system walls as well as natural convection and radiation heat transfer on the outer surface. Because of time-dependent effects a sensitivity analysis is performed to identify optimal time periods for data analysis. Results are compared with available literature data.

Experimental Study of Non-Condensable Effect on Passive Condenser System

2007 ◽  
Author(s):  
Wenzhong Zhou ◽  
Shripad T. Revankar
Keyword(s):  
Heat Transfer ◽  
Cooling System ◽  
Heat Removal ◽  
Scaling Analysis ◽  
Steam Condensation ◽  
Transfer Coefficients ◽  
Specific Design ◽  
Heat Transfer Coefficients ◽  
Removal Capacity ◽  
Safety Systems

One of the engineered safety systems in the advanced boiling water reactor is a passive containment cooling system (PCCS) which is composed of a number of vertical heat exchanger. A set of steam condensation experiments is conducted to evaluate the heat removal capacity of a PCCS condenser. A condensing tube is submerged in a water pool where condensation heat is transferred by secondary boiling heat transfer. The specific design of condensing tube is based on scaling analysis from the PCCS design of ESBWR. The two condensing tubes have same height (0.9m) but different inside diameters, 26.6mm and 52.5mm, respectively. Condensation heat transfer coefficients (HTC) are obtained under various test conditions, such as different primary pressure (150 – 450 kPa), inlet steam flow rate (1 – 5 g/s), air mass fraction (0 – 20%) and tube size (26.6 mm and 52.5 mm ID). The effects of these parameters to condensation performance are evaluated.

Microjet Impingement Cooling With Phase Change

2004 ◽  
Author(s):  
Evelyn N. Wang ◽  
Juan G. Santiago ◽  
Kenneth E. Goodson ◽  
Thomas W. Kenny
Keyword(s):  
Heat Transfer ◽  
Cooling System ◽  
Heated Surface ◽  
Heat Removal ◽  
Transfer Coefficients ◽  
Two Phase ◽  
Impingement Cooling ◽  
Heat Transfer Coefficients ◽  
High Heat Transfer ◽  
Wall Superheat

The large heat generation rates in contemporary microprocessors require new thermal management solutions. Two-phase microjet impingement cooling promises high heat transfer coefficients and effective cooling of hotspots. We have fabricated integrated microjet structures with heaters and temperature sensors to study local heat transfer at the impingement surface of a confined microjet. Circular jets with diameters less than 100 μm are machined in glass. Preliminary temperature measurements (for Rej = 100–500) suggest that heat transfer coefficients of 1000 W/m2C close to the jet stagnation zone can be achieved. As the flowrate of the jet is increased, a tradeoff in heat removal capability and wall superheat is observed. To aid in understanding the mechanism for wall superheat during boiling at the heated surface, the devices allow for optical access through the top of the device. However, the formation of vapor from the top reservoir makes visualization difficult. This study aids in the design of microjet heat sinks used for integration into a closed-loop cooling system.

Numerical Analysis of Heat Conduction in Cooling of Aluminum Extrusion

2002 ◽  
Author(s):  
Nicola Bianco ◽  
Oronzio Manca
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Cooling System ◽  
Heat Conduction Problem ◽  
Aluminum Extrusion ◽  
Transfer Coefficients ◽  
Lower Velocity ◽  
Heat Transfer Coefficients ◽  
Water Sprays ◽  
Volume Method

A thermal analysis of the cooling of an extruded aluminum alloy by means of water sprays is carried out. The heat conduction problem has been solved numerically by means of a finite volume method. The heat transfer coefficients used in the boundary conditions has been evaluated by means of spray heat transfer correlations, which relate these coefficients to the spray hydrodynamic parameters. The influence of the number of sprays and of the solid velocity has been investigated. Results show that the efficiency of the cooling system decreases as the number of jets increases. The efficiency of each spray increases with the velocity for the same number of sprays. As the workpiece velocity increases it needs to increase the number of sprays to obtain the same temperature difference between the entry and the exit of the cooling system. The greater the number of sprays related to the case with lower velocity, the smaller the increase of the number of sprays.

Impact of Ceramic Matrix Composite Topology on Friction Factor and Heat Transfer

2021 ◽  
Author(s):  
Trevor M. Cory ◽  
Ryan D. Edelson ◽  
Karen A. Thole ◽  
Tyler Vincent ◽  
San Quach ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Friction Factor ◽  
Convective Heat ◽  
Pressure Loss ◽  
Surface Topology ◽  
Transfer Coefficients ◽  
Pressure Losses ◽  
Heat Transfer Coefficients ◽  
Convective Heat Transfer Coefficients

Abstract Ceramic matrix composites (CMCs) are of interest for hot section components of gas turbine engines due to their low weight and favorable thermal properties. To implement this advanced composite in a gas turbine engine, characterizing the influence of CMC’s surface topology on heat transfer and cooling performance is critical. However, very few published studies have reported the flow and heat transfer effects caused by this unique surface topology. This study is an experimental and computational investigation to evaluate the effect of weave orientations, relevant to CMC surfaces, on the resulting pressure loss and convective heat transfer within an internal channel. The weave pattern was additively manufactured as the walls of a scaled-up coupon containing a single channel. For each of the three weave orientations, bulk pressure losses and convective heat transfer coefficients were measured over a range of Reynolds numbers. Scaling the pressure losses in terms of a friction factor and convective heat transfer coefficients in terms of a Nusselt number showed the importance of choosing the appropriate definition of the hydraulic diameter, which was particularly important for the friction factor. A coupon having one wall with the weave surface increased pressure loss and heat transfer compared to a smooth wall with the largest increases occurring when the CMC weave strands were perpendicular to the flow. Friction factor augmentations were much higher than heat transfer augmentations. When adding the weave to a second channel wall, pressure loss and heat transfer were further increased. Orienting the CMC strands perpendicular to the flow consistently showed the largest augmentations in heat transfer over a smooth channel, but at a much higher pressure loss penalty than that seen with the CMC strands parallel to the flow.

Spray Cooling of an Inverted Heated Surface

2006 ◽  
Author(s):  
Frank Pyrtle ◽  
Alberto D. Sato
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Cooling System ◽  
Heated Surface ◽  
Spray Cooling ◽  
Open Loop ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Water Sprays ◽  
Compressed Gas

Experiments were performed to determine heat transfer characteristics of water sprays impacting a flat, inverted surface. Using a compressed gas tank to provide motive force in an open loop spray cooling system, droplet sprays were produced without the assistance of an atomizing gas stream. A range of droplet volumetric fluxes was produced for cooling the inverted heated surface using a full-cone spray nozzle. Heat transfer curves were plotted in the form of heat flux as a function of wall temperature difference, for volumetric flow rates up to 627 mL/min, dissipating up to 451 W/cm2. Heat transfer coefficients were also determined as functions of heat flux. The results were compared to prior data for standard, downward spraying onto heated surfaces.

scholarly journals Comparison of Blade Cooling Performance Using Alternative Fluids

2002 ◽  
Author(s):  
Carlo Carcasci ◽  
Stefano Zecchi ◽  
Gianpaolo Oteri
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Gas Turbine ◽  
Film Cooling ◽  
Cooling System ◽  
Internal Heat ◽  
Transfer Coefficients ◽  
Cooling Systems ◽  
Heat Transfer Coefficients ◽  
Blade Cooling

CO2 emissions reduction has become an important topic, especially after Kyoto protocol. There are several ways to reduce the overall amount of CO2 discharged into the atmosphere, for example using alternative fluids such as steam or CO2. It is therefore interesting to analyze the consequences of their usage on overall performances of gas turbine and blade cooling systems. The presence of steam can be associated with combined or STIG cycle, whereas pure carbon dioxide or air-carbon dioxide mixtures are present in innovative cycles, where the exhaust gas is recirculated partially or even totally. In this paper we will analyze a commercial gas turbine, comparing different fluids used as working and cooling fluids. The different nature of the fluids involved determines different external heat transfer coefficients (external blade surface), different internal heat transfer coefficients (cooling cavities) and affects film cooling effectiveness, resulting in a change of the blade temperature distribution. Results show that the presence of steam and CO2 could determine a non negligible effect on blade temperature. This means that cooling systems need a deep investigation. A redesign of the cooling system could be required. In particular, results show that steam is well suited for internal cooling, whereas CO2 is better used in film cooling systems.

Validation of CFD and Coupled Fluid-Solid Modelling for a Direct Transfer Pre-Swirl System

2012 ◽  
Author(s):  
Umesh Javiya ◽  
John Chew ◽  
Nick Hills ◽  
Klaus Dullenkopf ◽  
Timothy Scanlon
Keyword(s):  
Heat Transfer ◽  
Heat Conduction ◽  
Thermal Stresses ◽  
Cooling System ◽  
Life Assessment ◽  
Direct Transfer ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Thermocouple Temperature ◽  
Cooling Air

The prediction of the pre-swirl cooling air delivery and disc metal temperature are important for the cooling system performance and the rotor disc thermal stresses and life assessment. In this paper, standalone 3D steady and unsteady CFD, and coupled FE-CFD calculations are presented for prediction of these temperatures. CFD results are compared with previous measurements from a direct transfer pre-swirl test rig. The predicted cooling air temperatures agree well with the measurement, but the nozzle discharge coefficients are under predicted. Results from the coupled FE-CFD analyses are compared directly with thermocouple temperature measurements and with heat transfer coefficients on the rotor disc previously obtained from a rotor disc heat conduction solution. Considering the modelling limitations, the coupled approach predicted the solid metal temperatures well. Heat transfer coefficients on the rotor disc from CFD show some effect of the temperature variations on the heat transfer coefficients. Reasonable agreement is obtained with values deduced from the previous heat conduction solution.

Heat Transfer Study in Oil Channels of a Power Transformer Winding ONAN Cooling System with and without Insulating Paper Based on Numerical Modeling

2012 ◽  
Vol 232 ◽  
pp. 757-764 ◽  
Author(s):  
Sina Salari ◽  
Amir Yousefi ◽  
M. Reza Nasrollahzadeh ◽  
Mostafa Khalilikhah
Keyword(s):  
Heat Transfer ◽  
Cooling System ◽  
Power Transformer ◽  
Transfer Coefficients ◽  
Boussinesq Model ◽  
Heat Transfer Coefficients ◽  
Insulating Paper ◽  
Transformer Winding ◽  
The One ◽  
Transfer Study

In this study 3 geometry for ONAN cooling system of power transformers are numerically simulated with (Perforated nomex) and without insulating papers (Netting tape). Geometries are A, RA, and R type. The A type has just axial channels. The RA type has radial and axial channels but there are no baffles to drive the flow into radial channels. The R type is like the RA type but with baffles. Insulating paper used in this study has some holes to cause some vortex in flow to increase heat transfer. The CFD code used is Fluent 6.3. To simulate flow in natural convection mode, Boussinesq model and pressure inlet and outlet boundary conditions are used. Results show that the most effective geometry is the one with baffles that drive flow in radial channels in addition to axial channels. Streamlines near the holes in papers show that that height of holes is too small to affect heat transfer and, so, the comparison between geometries with and without paper shows the types without paper have higher heat transfer coefficients.

Impact of Ceramic Matrix Composite Topology on Friction Factor and Heat Transfer

2021 ◽  
Vol 144 (3) ◽  
Author(s):  
Trevor M. Cory ◽  
Ryan D. Edelson ◽  
Karen A. Thole ◽  
Tyler Vincent ◽  
San Quach ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Friction Factor ◽  
Convective Heat ◽  
Pressure Loss ◽  
Surface Topology ◽  
Transfer Coefficients ◽  
Pressure Losses ◽  
Heat Transfer Coefficients ◽  
Convective Heat Transfer Coefficients

Abstract Ceramic matrix composites (CMCs) are of interest for hot section components of gas turbine engines due to their low weight and favorable thermal properties. To implement this advanced composite in a gas turbine engine, characterizing the influence of CMC’s surface topology on heat transfer and cooling performance is critical. However, very few published studies have reported the flow and heat transfer effects caused by this unique surface topology. This study is an experimental and computational investigation to evaluate the effect of weave orientations, relevant to CMC surfaces, on the resulting pressure loss and convective heat transfer within an internal channel. The weave pattern was additively manufactured as the walls of a scaled-up coupon containing a single channel. For each of the three weave orientations, bulk pressure losses and convective heat transfer coefficients were measured over a range of Reynolds numbers. Scaling the pressure losses in terms of a friction factor and convective heat transfer coefficients in terms of a Nusselt number showed the importance of choosing the appropriate definition of the hydraulic diameter, which was particularly important for the friction factor. A coupon having one wall with the weave surface increased pressure loss and heat transfer compared to a smooth wall with the largest increases occurring when the CMC weave strands were perpendicular to the flow. Friction factor augmentations were much higher than heat transfer augmentations. When adding the weave to a second channel wall, pressure loss and heat transfer were further increased. Orienting the CMC strands perpendicular to the flow consistently showed the largest augmentations in heat transfer over a smooth channel, but at a much higher pressure loss penalty than that seen with the CMC strands parallel to the flow.

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