On the Heat Transfer and Flow Structures’ Characteristics of the Turbine Blade Tip Underside With Dirt Purge Holes at Different Locations by Using Topological Analysis

2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Lei Luo ◽  
Zhiqi Zhao ◽  
Xiaoxu Kan ◽  
Dandan Qiu ◽  
Songtao Wang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Topological Analysis ◽  
Internal Heat ◽  
Gas Turbine Blade ◽  
Transfer Enhancement ◽  
Cooling Passage ◽  
The Impact

This paper numerically investigated the impact of the holes and their location on the flow and tip internal heat transfer in a U-bend channel (aspect ratio = 1:2), which is applicable to the cooling passage with dirt purge holes in the mid-chord region of a typical gas turbine blade. Six different tip ejection configurations are calculated at Reynolds numbers from 25,000 to 200,000. The detailed three-dimensional flow and heat transfer over the tip wall are presented, and the overall thermal performances are evaluated. The topological methodology, which is first applied to the flow analysis in an internal cooling passage of the blade, is used to explore the mechanisms of heat transfer enhancement on the tip wall. This study concludes that the production of the counter-rotating vortex pair in the bend region provides a strong shear force and then increases the local heat transfer. The side-mounted single hole and center-mounted double holes can further enhance tip heat transfer, which is attributed to the enhanced shear effect and disturbed low-energy fluid. The overall thermal performance of the optimum hole location is a factor of 1.13 higher than that of the smooth tip. However, if double holes are placed on the upstream of a tip wall, the tip surface cannot be well protected. The results of this study are useful for understanding the mechanism of heat transfer enhancement in a realistic gas turbine blade and for efficient designing of blade tips for engine service.

Experimental Study on Flow Behavior and Heat Transfer Enhancement with Distinct Dimpled Gas Turbine Blade Internal Cooling Channel

2021 ◽  
pp. 1-28
Author(s):  
Farah Nazifa Nourin ◽  
Ryoichi S. Amano
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Transfer Enhancement ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Thermal Performance ◽  
Diameter Ratio ◽  
Internal Cooling ◽  
Cooling Channel ◽  
Transfer Enhancement

Abstract The study presents the investigation on heat transfer distribution along a gas turbine blade internal cooling channel. Six different cases were considered in this study, using the smooth surface channel as a baseline. Three different dimples depth-to-diameter ratios with 0.1, 0.25, and 0.50 were considered. Different combinations of partial spherical and leaf dimples were also studied with the Reynolds numbers of 6,000, 20,000, 30,000, 40,000, and 50,000. In addition to the experimental investigation, the numerical study was conducted using Large Eddy Simulation (LES) to validate the data. It was found that the highest depth-to-diameter ratio showed the highest heat transfer rate. However, there is a penalty for increased pressure drop. The highest pressure drop affects the overall thermal performance of the cooling channel. The results showed that the leaf dimpled surface is the best cooling channel based on the highest Reynolds number's heat transfer enhancement and friction factor. However, at the lowest Reynolds number, partial spherical dimples with a 0.25 depth to diameter ratio showed the highest thermal performance.

The Application of Convective Cooling Enhancement of Span-Wise Cooling Holes in a Typical First Stage Turbine Blade

1991 ◽  
Author(s):  
D. J. Stankiewicz ◽  
T. R. Kirkham
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Reynolds Numbers ◽  
Transfer Enhancement ◽  
Test Rig ◽  
Heated Oil ◽  
Cooling Enhancement ◽  
Mach And Reynolds Numbers

A technique of heat transfer enhancement is investigated whereby the internal span-wise cooling passages of a typical first stage gas turbine blade are modified by the introduction of circumferential ribs. The technique is verified by the use of a test rig incorporating a heated internally ribbed tube operating at the same range of Mach and Reynolds numbers as the turbine blade as well as by a test rig incorporating actual production blades immersed in a heated oil bath.

Detailed Local Heat Transfer Measurements in a Model of a Dendritic Gas Turbine Blade Cooling Design

2011 ◽  
Author(s):  
James Batstone ◽  
David Gillespie ◽  
Eduardo Romero
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Large Scale ◽  
Surface Film ◽  
Internal Heat ◽  
Internal Cooling ◽  
Gas Turbine Blade ◽  
Lift Off ◽  
Number Of Branches

A novel form of gas turbine blade or vane cooling in which passages repeatedly branch within the wall of the cooled component is introduced in this paper. These so called dendritic cooling geometries offer particular performance improvements compared to traditional cooling holes where the external cross flow is low, and conventional films have a tendency to lift off the surface. In these regions improved internal cooling efficiency is achieved, while the coolant film is ejected at a low momentum ratio resulting in reduced aerodynamic losses between the film and hot gases, and a more effective surface film. By varying the number of branches of the systems at a particular location it is possible to tune the flow and heat transfer to the requirements at that location whilst maintaining the pressure margin. The additional loss introduced using the internal branching structure allows a full film-coverage arrangement of holes at the external blade surface. In this paper the results of transient heat transfer experiments characterising the internal heat transfer coefficient distribution in large scale models of dendritic passages are reported. Experiments were conducted with 1, 2 and 3 internal flow branches at a range of engine representative Reynolds numbers and exit momentum ratios. CFD models are used to help explain the flow field in the cooling passages. Furthermore the sensitivity of the pressure loss to the blowing ratio at the exit of the cooling holes is characterised and found to be inversely proportional to the number of branches in the dendritic system. Surprisingly the highly branched systems generally do not exhibit the highest pressure losses.

Heat Transfer Enhancement for Gas Turbine Internal Cooling by Application of Double Swirl Cooling Chambers

2013 ◽  
Author(s):  
Karsten Kusterer ◽  
Gang Lin ◽  
Dieter Bohn ◽  
Takao Sugimoto ◽  
Ryozo Tanaka ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Gas Turbine ◽  
Internal Heat ◽  
Numerical Results ◽  
Internal Cooling ◽  
Transfer Enhancement ◽  
Cooling Channels ◽  
Swirl Chamber ◽  
Internal Heat Transfer

Improvement of the gas turbine thermal efficiency can be achieved by reducing the cooling fluid amount in internal cooling channels with enhanced convective cooling. Nowadays the state of the art internal cooling technology for thermally high-loaded gas turbine blades consists of multiple serpentine-shaped cooling channels with angled ribs. Besides, huge effort is put on the development of more advanced internal cooling configurations with further internal heat transfer enhancements. Swirl chamber flow configurations, in which air is flowing through a pipe with a swirling motion generated by tangential jet inlet, have a potential for application as such advanced technology. This paper presents the validation of numerical results for a standard swirl chamber, which has been investigated experimentally in a reference publication. The numerical results obtained with application of the SST k-ω model show the best agreement with the experiment data in compare with other turbulence models. It has been found at the inlet region that the augmentation of the heat transfer is nearly seven times larger than the fully developed non-swirl flow. Within the further numerical study, another cooling configuration named Double Swirl Chambers (DSC) has been obtained and investigated. The numerical results are compared to the reference case. With the same boundary conditions and Reynolds number, the heat transfer coefficients are higher for the DSC configuration than for the reference configuration. In particular at the inlet region, the DSC configuration has even higher circumferentially averaged heat transfer enhancement in one section by approximately 41%. The globally-averaged heat transfer enhancement in DSC configuration is 34.5% higher than the value in the reference SC configuration. This paper presents the configuration of the DSC as an alternative internal cooling technology and explains its major physical phenomena, which are the reasons for the improvement of internal heat transfer.

Unsteady CFD Analysis of Turbulent Flow and Heat Transfer in a Gas Turbine Blade Trailing Edge Subjected to Rotation

2012 ◽  
Author(s):  
Domenico Borello ◽  
Giovanni Delibra ◽  
Cosimo Bianchini ◽  
Antonio Andreini
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Heated Surface ◽  
Heat Removal ◽  
Gas Turbine Blade ◽  
Trailing Edge ◽  
Flow And Heat Transfer ◽  
The Impact

Internal cooling of gas turbine blade represents a challenging task involving several different phenomena as, among others, highly three-dimensional unsteady fluid flow, efficient heat transfer and structural design. This paper focuses on the analysis of the turbulent flow and heat transfer inside a typical wedge–shaped trailing edge cooling duct of a gas turbine blade. In the configuration under scrutiny the coolant flows inside the duct in radial direction and it leaves the blade through the trailing edge after a 90 deg turning. At first an analysis of the flow and thermal fields in stationary conditions was carried out. Then the effects of rotational motion were investigated for a rotation number of 0.275. The rotation axis here considered is normal to the inflow and outflow bulk velocity, representing schematically a highly loaded blade configuration. The work aimed to i) analyse the dynamic of the vortical structures under the influence of strong body forces and the constraints induced by the internal geometry and ii) to study the impact of such motions on the mechanisms of heat removal. The final aim was to verify the design of the equipment and to detect the possible presence of regions subjected to high thermal loads. The analysis is carried out using the well assessed open source code OpenFOAM written in C++ and widely validated by several scientists and researchers around the world. The unsteadiness of the flow inside the trailing edge required to adopt models that accurately reconstructed the flow field. As the computational costs associated to LES (especially in the near wall regions) largely exceed the available resources, we chose for the simulation the SAS model of Menter, that was validated in a series of benchmark and industrially relevant test cases and allowed to reconstruct a part of the turbulence spectra through a scale-adaptive mechanism. Assessment of the obtained results with steady-state k-ω SST computations and available experimental results was carried out. The present analysis demonstrated that a strong unsteadiness develops inside the trailing edge and that the rotation generated strong secondary motions that enhanced the dynamic of heat removal, leading to a less severe temperature distribution on the heated surface w.r.t the non rotating case.

Numerical Investigation on the Modified Bend Geometry of a Rotating Multipass Internal Cooling Passage in a Gas Turbine Blade

2018 ◽  
Vol 10 (6) ◽  
Author(s):  
Naris Pattanaprates ◽  
Ekachai Juntasaro ◽  
Varangrat Juntasaro
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Internal Cooling ◽  
Gas Turbine Blade ◽  
Reduced Pressure ◽  
Improve Heat Transfer ◽  
Cooling Passage ◽  
Internal Cooling Passage

Abstract The present work is aimed to investigate whether the modification to the bend geometry of a multipass internal cooling passage in a gas turbine blade can enhance heat transfer and reduce pressure drop. The two-pass channel and the four-pass channel are modified at the bend from the U shape to the bulb and bow shape. The first objective of the work is to investigate whether the modified design will still improve heat transfer with reduced pressure drop in a four-pass channel as in the case of a two-pass channel. It is found out that, unlike the two-pass channel, the heat transfer is not improved but the pressure drop is still reduced for the four-pass channel. The second objective is to investigate the rotating effect on heat transfer and pressure drop in the cases of two-pass and four-pass channels for both original and modified designs. It is found out that heat transfer is improved with reduced pressure drop for all cases. However, the modified design results in the less improvement on heat transfer and lower reduced pressure drop as the rotation number increases. It can be concluded from the present work that the modification can solve the problem of pressure drop without causing the degradation of heat transfer for all cases. The two-pass channel with modified bend results in the highest heat transfer and the lowest pressure drop for rotating cases.

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