Experimental and numerical investigations of internal heat transfer in an innovative trailing edge blade cooling system: stationary and rotation effects, part 1—experimental results

2016 ◽  
Vol 53 (2) ◽  
pp. 475-490 ◽  
Author(s):  
Ahmed Beniaiche ◽  
Adel Ghenaiet ◽  
Bruno Facchini
Keyword(s):  
Heat Transfer ◽  
Cooling System ◽  
Internal Heat ◽  
Experimental Results ◽  
Trailing Edge ◽  
Numerical Investigations ◽  
Blade Cooling ◽  
Internal Heat Transfer

Heat Transfer in a Vane Trailing Edge Passage With Conical Pins and Pin-Turbulator Integrated Configurations

2014 ◽  
Author(s):  
J. Kruekels ◽  
S. Naik ◽  
A. Lerch ◽  
A. Sedlov
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Gas Turbine ◽  
Internal Heat ◽  
Transfer Coefficients ◽  
Trailing Edge ◽  
Heat Transfer Coefficients ◽  
Trailing Edges ◽  
Converging Channel ◽  
Internal Heat Transfer

The trailing edge sections of gas turbine vanes and blades are generally subjected to extremely high heat loads due to the combined effects of high external accelerating Mach numbers and gas temperatures. In order to maintain the metal temperatures of these trailing edges to a level, which fulfills the mechanical integrity of the parts, highly efficient cooling of the trailing edges is required without increasing the coolant consumption, as the latter has a detrimental effect on the overall gas turbine performance. In this paper the characteristics of the heat transfer and pressure drop of two novel integrated pin bank configurations were investigated. These include a pin bank with conical pins and a pin bank consisting of cylindrical pins and intersecting broken turbulators. As baseline case, a pin bank with cylindrical pins was studied as well. All investigations were done in a converging channel in order to be consistent with the real part. The heat transfer and pressure drop of all the pin banks were investigated initially with the use of numerical predictions and subsequently in a scaled experimental wind tunnel. The experimental study was conducted for a range of operational Reynolds numbers. The TLC (thermochromic liquid crystal) method was used to measure the detailed heat transfer coefficients in scaled Perspex models representing the various pin bank configurations. Pressure taps were located at several positions within the test sections. Both local and average heat transfer coefficients and pressure loss coefficients were determined. The measured and predicted results showed that the local internal heat transfer coefficient increases in the flow direction. This was due to the flow acceleration in the converging channel. Furthermore, both the broken ribs and the conical pin banks resulted in higher heat transfer coefficients compared with the baseline cylindrical pins. The conical pins produced the highest average internal heat transfer coefficients in contrast to the pins with the broken ribs, though this was also associated with a higher pressure drop.

Blade Trailing Edge Heat Transfer

1980 ◽  
Author(s):  
A. Brown ◽  
B. Mandjikas ◽  
J. M. Mudyiwa
Keyword(s):  
Heat Transfer ◽  
Turbine Blades ◽  
Internal Heat ◽  
Maximum Velocity ◽  
Reynolds Numbers ◽  
Trailing Edge ◽  
Pillar Diameter ◽  
Trailing Edges ◽  
Pillar Arrays ◽  
Internal Heat Transfer

In this article measurements of heat transfer, pressure loss, and friction factor inside simulated trailing edges of turbine blades are presented. The trailing edges considered are vented and the internal heat transfer surfaces are extended by means of staggered arrays of pillars interconnecting the blade pressure and suction surfaces. A number of pillar arrays and trailing edge configurations are considered, namely pillar pitch to diameter ratios nominally of 2, 3, and 4 and trailing edge included angles of 0, 10, 15, and 20 deg. The range of Reynolds numbers covered based on pillar diameter and maximum velocity through a row of pillars is from 104 to 2 × 105.

Full Thermal Experimental Assessment of a Dendritic Turbine Vane Cooling Scheme

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
S. Luque ◽  
J. Batstone ◽  
D. R. H. Gillespie ◽  
T. Povey ◽  
E. Romero
Keyword(s):  
Heat Transfer ◽  
Cooling System ◽  
Pressure Ratio ◽  
Internal Heat ◽  
Flux Ratio ◽  
Internal Cooling ◽  
Cooling Effectiveness ◽  
Experimental Assessment ◽  
Film Cooling Effectiveness ◽  
Internal Heat Transfer

A full thermal experimental assessment of a novel dendritic cooling scheme for high-pressure turbine vanes has been conducted and is presented in this paper, including a comparison to the current state-of-the-art cooling arrangement for these components. The dendritic cooling system consists of cooling holes with multiple internal branches that enhance internal heat transfer and reduce the blowing ratio at hole exit. Three sets of measurements are presented, which describe, first, the local internal heat transfer coefficient of these structures and, secondly, the cooling flow capacity requirements and overall cooling effectiveness of a highly engine-representative dendritic geometry. Full-coverage surface maps of overall cooling effectiveness were acquired for both dendritic and baseline vanes in the Annular Sector Heat Transfer Facility, where scaled near-engine conditions of Mach number, Reynolds number, inlet turbulence intensity, and coolant-to-mainstream pressure ratio (or momentum flux ratio) are achieved. Engine hardware was used, with laser-sintered metal counterparts for the novel cooling geometry (their detailed configuration, design, and manufacture are discussed). The dendritic system will be shown to offer improved overall cooling effectiveness at a reduced cooling mass flow rate due to a more uniform film cooling effectiveness, a decreased tendency for films to lift off in regions of low external cross flow, improved through-wall heat transfer and internal cooling efficiency, increased internal wetted surface area of the cooling holes, and the enhanced turbulence induced in them.

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.

Development and Application of an Internal Heat-Transfer Measurement Technique for Cooled Real Engine Components

2020 ◽  
Author(s):  
Asif Ali ◽  
Lorenzo Cocchi ◽  
Alessio Picchi ◽  
Bruno Facchini ◽  
Simone Cubeda
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Measurement Technique ◽  
Cooling System ◽  
Convective Heat Transfer Coefficient ◽  
Internal Heat ◽  
Test Duration ◽  
External Temperature ◽  
Ir Camera ◽  
Internal Heat Transfer

Abstract The aim of this work is to present the development and application of a measurement technique that allows to record internal heat transfer features of real components. In order to apply this method, based on similar approaches proposed in previous literature works, the component is initially heated up to a steady temperature, then a thermal transient is induced by injecting cool air in the internal cooling system. During this process, the external temperature evolution is recorded by means of an IR camera. Experimental data are then exploited to run a numerical procedure, based on a series of transient finite-element analyses of the component. In particular, the test duration is divided into an appropriate number of steps and, for each of them, the heat flux on internal surfaces is iteratively updated as to target the measured external temperature distribution. Heat flux and internal temperature data for all the time steps are eventually employed in order to evaluate the convective heat transfer coefficient via linear regression. This technique has been successfully tested on a cooled high-pressure vane of a Baker Hughes heavy-duty gas turbine, which was realised thanks to the development of a dedicated test rig at the University of Florence, Italy. The obtained results provide sufficiently detailed heat transfer distributions in addition to allowing to appreciate the effect of different coolant mass flow rates. The methodology is also capable of identifying defects, which is demonstrated by inducing controlled faults in the component.

Full Thermal Experimental Assessment of a Dendritic Turbine Vane Cooling Scheme

2012 ◽  
Author(s):  
S. Luque ◽  
J. Batstone ◽  
D. R. H. Gillespie ◽  
T. Povey ◽  
E. Romero
Keyword(s):  
Heat Transfer ◽  
Cooling System ◽  
Pressure Ratio ◽  
Internal Heat ◽  
Flux Ratio ◽  
Internal Cooling ◽  
Cooling Effectiveness ◽  
Experimental Assessment ◽  
Film Cooling Effectiveness ◽  
Internal Heat Transfer

A full thermal experimental assessment of a novel dendritic cooling scheme for high-pressure turbine vanes has been conducted and is presented in this paper, including comparisons to the conventional cooling arrangement for these components. The dendritic cooling system consists of cooling holes with multiple internal branches which enhance internal heat transfer and reduce the blowing ratio at hole exit. Three sets of measurements are presented, which describe, first, the local internal heat transfer coefficient of these structures, and, secondly, the cooling flow capacity requirements and overall cooling effectiveness of a highly engine-representative dendritic geometry. Full-coverage surface maps of overall cooling effectiveness were acquired for both dendritic and baseline vanes in the Annular Sector Heat Transfer Facility, where scaled near-engine conditions of Mach number, Reynolds number, inlet turbulence intensity and coolant-to-mainstream pressure ratio (or momentum flux ratio) are achieved. Engine hardware was used, with laser-sintered metal counterparts for the novel cooling geometry (their detailed configuration, design, and manufacture are discussed). The dendritic system will be shown to offer improved overall cooling effectiveness at a reduced cooling mass flow rate due to a more uniform film cooling effectiveness, a decreased tendency for films to lift off in regions of low external cross flow, improved through-wall heat transfer and internal cooling efficiency, increased internal wetted surface area of the cooling holes, and the enhanced turbulence induced in them.

TLC Measurements of Heat Transfer Under Rotating Conditions at High Reynolds Number in an Innovative Trailing Edge Cooling System

2012 ◽  
Author(s):  
Ahmed Beniaiche ◽  
Leonardo Bonanni ◽  
Carlo Carcasci
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Cooling System ◽  
Internal Cooling ◽  
Flow Conditions ◽  
High Pressure Turbine ◽  
Trailing Edge ◽  
Blade Cooling ◽  
Typical Shape ◽  
High Reynolds

TLC experimental measurements were conducted, to study the effect of an aerothermal performances of a 30:1 PMMA scaled trailing edge (TE) model reproducing an internal cooling system under stationary and rotating conditions. The studied geometry, selected capitalizing the experience about industrial collaboration, reproduces the typical shape of ribbed surface (with an angular orientation of 60 [deg] with respect to the radial direction) of a high pressure turbine blade TE, with one row of enlarged pedestals. The airflow pattern inside the device simulates a highly loaded rotor blade cooling scheme with a 90[deg] turning flow from the radial hub inlet to the tangential TE outlet. Detailed heat transfer coefficient 2D maps describing the experimental results of the effect of different rotating number [in the range from 0 to 0.3 for a fixed Reynolds number of 10000, and in the range from 0 to 0.15 corresponding to diverse Reynolds number varying from 20000 to 40000] are presented. The effect of the rotation on the heat transfer variation at different Reynolds number is highlighted by a comparison with static settings at the same flow conditions.

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