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.

scholarly journals Effect of Rotation on a Gas Turbine Blade Internal Cooling System: Experimental Investigation

2016 ◽  
Author(s):  
Daniele Massini ◽  
Emanuele Burberi ◽  
Carlo Carcasci ◽  
Lorenzo Cocchi ◽  
Bruno Facchini ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Flow Field ◽  
Transfer Coefficient ◽  
Cooling System ◽  
Cross Flow ◽  
Leading Edge ◽  
Impinging Jets ◽  
Internal Cooling ◽  
Transfer Pattern

A detailed aerothermal characterization of an advanced leading edge cooling system has been performed by means of experimental measurements. Heat transfer coefficient distribution has been evaluated exploiting a steady-state technique using Thermocromic Liquid Crystals (TLC), while flow field has been investigated by means of Particle Image Velocimetry (PIV). The geometry key features are the multiple impinging jets and the four rows of coolant extraction holes, which mass flow rate distribution is representative of real engine working conditions. Tests have been performed in both static and rotating conditions, replicating a typical range of jet Reynolds number (Rej), from 10000 to 40000, and Rotation number (Roj) up to 0.05. Different cross-flow conditions (CR) have been used to simulate the three main blade regions (i.e. tip, mid and hub). The aerothermal field turned out to be rather complex, but a good agreement between heat transfer coefficient and flow field measurement has been found. In particular, jet bending strongly depends on crossflow intensity, while rotation has a weak effect on both jet velocity core and area-averaged Nusselt number. Rotational effects increase for the lower cross-flow tests. Heat transfer pattern shape has been found to be substantially Reynolds-independent.

A Comparison of Full Surface Local Heat Transfer Coefficient and Flow Field Studies Beneath Sharp-Edged and Radiused Entry Impinging Jets

1996 ◽  
Author(s):  
D. R. H. Gillespie ◽  
S. M. Guo ◽  
Z. Wang ◽  
P. T. Ireland ◽  
S. T. Kohler
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Flow Field ◽  
Transfer Coefficient ◽  
Large Scale ◽  
Static Pressure ◽  
Local Heat Transfer ◽  
Target Surface ◽  
Impinging Jets ◽  
Velocity Variation

Full heat transfer coefficient and static pressure distributions have been measured on the target surface under impinging jets formed by sharp-edged and large entry radius holes. These geometries are representative of impingement holes in a gas turbine blade manufactured by laser cutting and by casting, respectively. Target surface heat transfer has been measured in a large scale perspex rig using both the transient liquid crystal technique and hot thin film gauges. A range of jet Reynolds numbers, representative of engine conditions, has been investigated. The velocity variation has been calculated from static pressure measurements on the impingement target surface. The heat transfer to the target surface is discussed in terms of the interpreted flow field.

scholarly journals Effect of Rotation on a Gas Turbine Blade Internal Cooling System: Experimental Investigation

2017 ◽  
Vol 139 (10) ◽  
Author(s):  
Daniele Massini ◽  
Emanuele Burberi ◽  
Carlo Carcasci ◽  
Lorenzo Cocchi ◽  
Bruno Facchini ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Flow Field ◽  
Transfer Coefficient ◽  
Cooling System ◽  
Leading Edge ◽  
Impinging Jets ◽  
Internal Cooling ◽  
Coefficient Distribution ◽  
Transfer Pattern

A detailed aerothermal characterization of an advanced leading edge (LE) cooling system has been performed by means of experimental measurements. Heat transfer coefficient distribution has been evaluated exploiting a steady-state technique using thermochromic liquid crystals (TLCs), while flow field has been investigated by means of particle image velocimetry (PIV). The geometry key features are the multiple impinging jets and the four rows of coolant extraction holes, and their mass flow rate distribution is representative of real engine working conditions. Tests have been performed in both static and rotating conditions, replicating a typical range of jet Reynolds number (Rej), from 10,000 to 40,000, and rotation number (Roj) up to 0.05. Different crossflow conditions (CR) have been used to simulate the three main blade regions (i.e., tip, mid, and hub). The aerothermal field turned out to be rather complex, but a good agreement between heat transfer coefficient and flow field measurement has been found. In particular, jet bending strongly depends on crossflow intensity, while rotation has a weak effect on both jet velocity core and area-averaged Nusselt number. Rotational effects increase for the lower crossflow tests. Heat transfer pattern shape has been found to be substantially Reynolds independent.

Flow Field and Heat Transfer Characteristics in an Impingement/Effusion Cooling System for Combustor Liner

2005 ◽  
Author(s):  
Quanhong Xu ◽  
Chi Zhang ◽  
Yuzhen Lin ◽  
Gaoen Liu
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Flow Field ◽  
Transfer Coefficient ◽  
Cooling System ◽  
Impingement Jet ◽  
Impingement Heat Transfer ◽  
Double Skin ◽  
Combustor Liner ◽  
Effusion Hole

The present study is conducted to investigate the characteristics of the flow field and heat transfer in an impingement/effusion cooling scheme for gas turbine combustor liner. It is designed to provide an insight, through the study of the flow field, into the physical mechanisms responsible for the enhanced impingement heat transfer near the effusion hole entrance. In this impingement/effusion cooling scheme, the angle between the impingement hole and effusion hole and the wall surface are 90 deg and 30 deg respectively. The square arrays of impingement/effusion holes are used with equal numbers of holes offset half a pitch relative to each plate so that an impingement jet is located on the center of each four effusion holes and vice versa. The flow field of the double skin wall space is described by the way of Particle Image Velocimetry (PIV). Two kinds of target plates, with and without effusion holes, are used in the impingement heat transfer study. Through changing the impingement Reynolds and the impingement gap, the change of the impingement heat transfer coefficient on the target plates is investigated. The impingement heat transfer test results show that the impingement heat transfer is enhanced near the entrance of the effusion holes, which could fully explain the feature of the impingement heat transfer coefficient on the target plate.

Experimental Study of Advanced Convective Cooling Techniques for Combustor Liners

2008 ◽  
Author(s):  
Michael Maurer ◽  
Uwe Ruedel ◽  
Michael Gritsch ◽  
Jens von Wolfersdorf
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Reynolds Number ◽  
Heat Transfer Coefficient ◽  
Flow Field ◽  
Transfer Coefficient ◽  
Heat Transfer Enhancement ◽  
Transfer Enhancement ◽  
Number Range ◽  
Convective Cooling

An experimental study was conducted to determine the heat transfer performance of advanced convective cooling techniques at the typical conditions found in a backside cooled combustion chamber. For these internal cooling channels, the Reynolds number is usually found to be above the Reynolds number range covered by available databases in the open literature. As possible candidates for an improved convective cooling configuration in terms of heat transfer augmentation and acceptable pressure drops, W-shaped and WW-shaped ribs were considered for channels with a rectangular cross section. Additionally, uniformly distributed hemispheres were investigated. Here, four different roughness spacings were studied to identify the influence on friction factors and the heat transfer enhancement. The ribs and the hemispheres were placed on one channel wall only. Pressure losses and heat transfer enhancement data for all test cases are reported. To resolve the heat transfer coefficient, a transient thermocromic liquid crystal technique was applied. Additionally, the area-averaged heat transfer coefficient on the W-shaped rib itself was observed using the so-called lumped-heat capacitance method. To gain insight into the flow field and to reveal the important flow field structures, numerical computations were conducted with the commercial code FLUENT™.

Effect of Rotation on a Gas Turbine Blade Internal Cooling System: Numerical Investigation

2016 ◽  
Author(s):  
E. Burberi ◽  
D. Massini ◽  
L. Cocchi ◽  
L. Mazzei ◽  
A. Andreini ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Flow Field ◽  
Transfer Coefficient ◽  
Numerical Investigation ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Cooling System ◽  
Leading Edge ◽  
Internal Cooling

Increasing turbine inlet temperature is one of the main strategies used to accomplish the demands of increased performance of modern gas turbines. As a consequence, optimization of the cooling system is of paramount importance in gas turbine development. Leading edge represents a critical part of cooled nozzles and blades, given the presence of the hot gases stagnation point and the unfavourable geometry for cooling. This paper reports the results of a numerical investigation aimed at assessing the rotation effects on the heat transfer distribution in a realistic leading edge internal cooling system of a high pressure gas turbine blade. The numerical investigation was carried out in order to support and to allow an in-depth understanding of the results obtained in a parallel experimental campaign. The model is composed of a trapezoidal feeding channel which provides air to the cold bridge system by means of three large racetrack-shaped holes, generating coolant impingement on the internal concave leading edge surface, whereas four big fins assure the jets confinement. Air is then extracted through 4 rows of 6 holes reproducing the external cooling system composed of shower-head and film cooling holes. Experiments were performed in static and rotating conditions replicating the typical range of jet Reynolds number (Rej) from 10000 to 40000 and Rotation number (Roj) up to 0.05, for three crossflow cases representative of the working condition that can be found at blade tip, midspan and hub, respectively. Experimental results in terms of flow field measurements on several internal planes and heat transfer coefficient on the LE internal surface have been performed on two analogous experimental campaigns at University of Udine and University of Florence respectively. Hybrid RANS-LES models were used for the simulations, such as Scale Adaptive Simulation (SAS) and Detached Eddy Simulation (DES), given their ability to resolve the complex flow field associated with jet impingement. Numerical flow field results are reported in terms of both jet velocity profiles and 2D vector plots on symmetry and transversal internal planes, while the heat transfer coefficient distributions are presented as detailed 2D maps together with radial and tangential averaged Nusselt number profiles. A fairly good agreement with experimental measurements is observed, which represent a validation of the adopted computational model. As a consequence, the computed aerodynamic and thermal fields also allow an in-depth interpretation of the experimental results.

Detailed Heat Transfer Coefficient Distributions on a Large-Scale Gas Turbine Blade Tip

2000 ◽  
Vol 123 (4) ◽  
pp. 803-809 ◽  
Author(s):  
Shuye Teng ◽  
Je-Chin Han ◽  
G. M. S. Azad
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Wind Tunnel ◽  
Transfer Coefficient ◽  
Turbine Blade ◽  
Large Scale ◽  
Tip Clearance ◽  
Low Speed ◽  
Blade Tip ◽  
Low Speed Wind Tunnel

Measurements of detailed heat transfer coefficient distributions on a turbine blade tip were performed in a large-scale, low-speed wind tunnel facility. Tests were made on a five-blade linear cascade. The low-speed wind tunnel is designed to accommodate the 107.49 deg turn of the blade cascade. The mainstream Reynolds number based on cascade exit velocity was 5.3×105. Upstream unsteady wakes were simulated using a spoke-wheel type wake generator. The wake Strouhal number was kept at 0 or 0.1. The central blade had a variable tip gap clearance. Measurements were made at three different tip gap clearances of about 1.1 percent, 2.1 percent, and 3 percent of the blade span. Static pressure distributions were measured in the blade mid-span and on the shroud surface. Detailed heat transfer coefficient distributions were measured on the blade tip surface using a transient liquid crystal technique. Results show that reduced tip clearance leads to reduced heat transfer coefficient over the blade tip surface. Results also show that reduced tip clearance tends to weaken the unsteady wake effect on blade tip heat transfer.

Unsteady Analysis of Heat Transfer Coefficient Distribution in a Static Ribbed Channel for an Established Flow

2020 ◽  
Author(s):  
Aurélien Perrot ◽  
Laurent Gicquel ◽  
Florent Duchaine ◽  
Nicolas Odier ◽  
Jérôme Dombard ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Flow Field ◽  
Transfer Coefficient ◽  
Large Scale ◽  
Weak Link ◽  
Turbine Blades ◽  
Main Flow ◽  
Dynamic Mode Decomposition ◽  
Dynamic Mode

Abstract Turbulent ribbed channels are extensively used in turbomachinery to enhance convective heat transfer in internally-cooled components like turbine blades. One of the key aspect of such a problem is the distribution of the Heat Transfer Coefficient (HTC) in fully developed flows and many studies have addressed this problem by use of Computational Fluid Dynamics (CFD). In the present document, Large Eddy Simulation (LES) is performed for a configuration from a test-rig at the Von Karman Institute representing a square channel with periodic square ribs. The whole channel is computed in an attempt to better understand HTC maps in this specific configuration. Resulting mean and unsteady flow features are captured and predictions are used to further explain the obtained HTC distribution. More specifically turbulent structures are seen to bring cold gas from the main flow to the wall. A statistical analysis of these events using the joint velocity-temperature PDF and quadrant method allows to define 4 types of events happening at every location of the channel and which can then be linked to the HTC distribution. First the HTC is very high where the flow impacts the wall with cold temperature whereas it is lower where the hot gas is ejected to the main flow. In an attempt to link the HTC trace on the channel wall with structures in the flow field far-off the wall, the main modes are identified performing Power Spectral Density (PSD) analysis of the velocity along the channel. Dynamic Mode Decomposition (DMD) of the flow field data is then used to present the spatio-temporal characteristics of two of the identified most dominant modes: a vortex-street mode linked to the first rib and a rib-to-rib mode appearing because of the quasi-periodicity of the configuration. However DMD analysis of the HTC trace on the wall does not emphasize any dominant mode. This indicates a weak link between the main flow large scale features and the instantaneous and more local HTC distribution.

Heat Transfer and Pressure Drop Characteristics for a Turbine Casing Impingement Cooling System

2010 ◽  
Author(s):  
F. Ben Ahmed ◽  
B. Weigand ◽  
K. Meier
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Coefficient ◽  
Mach Number ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Cooling System ◽  
Impinging Jets ◽  
Turbine Casing ◽  
The Heat Transfer Coefficient

Flow mechanisms, heat transfer and discharge coefficient characteristics for a representative part of a turbine casing cooling system, consisting of an array of 20 impinging jets, were numerically investigated. The study focused on the influence of the jet Mach number while maintaining the Reynolds number constant at Re = 7,500. Therefore, the orifice bore diameter or the fluid density had to be varied. The objectives of the current CFD simulations have not been adressed before in literature, not only because heat transfer characteristics and pressure drop are given for impingement jet Mach numbers up to 0.72 at a constant relatively low Reynolds number, but also because fundamental understanding of physical phenomena of the flow in the cylindrical plenum and in the small sharp-edged orifices at the bottom side of the tube is provided. Increasing the Mach number by simultaneously reducing the orifice diameters led to slightly decreasing Nusselt numbers, with average deviations of the order of 14%. However, the heat transfer coefficient increased considerably with increasing Mach number. On the contrary, the variation of the Mach number by varying the density showed only a slight influence on the heat transfer coefficient. The predicted discharge coefficients increased significantly by augmenting the Mach number.

Measurement of Heat Transfer Coefficient Distributions and Flow Field in a Model of a Turbine Blade Cooling Passage With Tangential Injection

2006 ◽  
Author(s):  
John P. C. W. Ling ◽  
Peter T. Ireland ◽  
Neil W. Harvey
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Flow Field ◽  
Transfer Coefficient ◽  
Cooling System ◽  
High Heat ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
High Heat Transfer ◽  
Cooling Passage

In certain regions of turbine aerofoils, cooling system designers need to cool the blades with convection systems that provide high heat transfer coefficients. The present research has investigated a circular cooling passage with tangential injection suitable for a blade leading edge. The heat transfer coefficients are measured using the conventional transient heat transfer, liquid crystal technique. The results are compared to the data from steady state experiments performed by Hedlund et al. [1]. The cooling system performance is compared in detail to average data from earlier tangential injection experiments and to local heat transfer coefficient expected from a normal impingement system. The vortex flow field was also studied by numerical prediction and near-wall velocity measurements. The investigation of the flow structure has led to understanding of flow mechanisms responsible for the high heat transfer coefficient. The vortex flow field was also investigated using computational fluid dynamics and with hot wire anemometry. The latter near wall measurements were combined with the law of the wall and Colburn analogy to validate the flow and heat transfer measurements.

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