Numerical Investigation of Heat Transfer and Pressure Drop Characteristics for Different Hole Geometries of a Turbine Casing Impingement Cooling System

Ahmed, Fawad; Tucholke, R.; Meier, K.

doi:10.1115/gt2011-45251

Cited by 11 publications

(9 citation statements)

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“…In such configuration Lichtarowicz et al [24] shows that, in term of C d , holes with t=d ¼ 3 behaves as hole with t=d ¼ 2. In the case of t=d ¼ 0:25 (geometry labeled I), the predicted discharge coefficients are close to those related to geometry H for the major part of the holes while, approaching the end of the manifold, the C d remains constant as already pointed out also by Ahmed et al [18,19]. For these reasons, the geometry I was not considered for the definition of the improved correlation.…”

Section: Effects Of the T/dmentioning

confidence: 98%

“…This assumption can be safely accepted taking into account that actual ACC cooling jets are usually injected in low velocity cross flow (Ma ( 0:1 as confirmed by the investigations reported in Da Soghe and coworkers [22] and also by Gritsch et al [9]), sufficiently far from cooled wall to avoid the effects of stagnation point and heat transfer on jet discharge losses. [19] 031017-2 / Vol. 135, MAY 2013…”

Section: Description Of Geometries and Test Matrixmentioning

confidence: 99%

“…More recently, Ahmed et al [18,19] performed some numerical simulation of the flow in a short tube section of an ACC system for a low pressure turbine aimed at the prediction of impingement jet characteristics in form of discharge coefficients, local and spatially averaged Nusselt numbers and heat transfer coefficients. The length-to-diameter ratio of the sharp-edged cylindrical holes, ranged from 0:25 to 2, was also accounted.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Characterization of Pressure Drop Across the Manifold of Turbine Casing Cooling System

Soghe¹,

Andreini

2013

Journal of Turbomachinery

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An array of jets is an arrangement typically used to cool several gas turbine parts. Some examples of such applications can be found in the impingement cooling systems of turbine blades and vanes or in the turbine blade tip clearances control of large aero-engines. In order to correctly evaluate the impinging jet mass flow rate, the characterization of holes discharge coefficient is a compulsory activity. In a previous work, the authors have performed an aerodynamic analysis of different arrays of jets for active clearance control; the aim was the definition of a correlation for the discharge coefficient (C d ) of a generic hole of the array. The developed empirical correlation expresses the (C d ) of each hole as a function of the ratio between the hole and the manifold mass velocity and the local value of the pressure ratio. In its original form, the correlation does not take in to account the effect of the hole length to diameter ratio (t/d) so, in the present contribution, the authors report a study with the aim of evaluating the influence of such parameter on the discharge coefficient distribution. The data were taken from a set of CFD RANS simulations, in which the behavior of the cooling system was investigated over a wide range of fluid-dynamics conditions (pressure-ratio ¼ 1.01-1.6, t/d ¼ 0.25-3). To point out the reliability of the CFD analysis, some comparisons with experimental data were drawn. An in depth analysis of the numerical data set has led to an improved correlation with a new term function of the hole length to diameter ratio.

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Section: Effects Of the T/dmentioning

confidence: 98%

Section: Description Of Geometries and Test Matrixmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Numerical Characterization of Pressure Drop Across the Manifold of Turbine Casing Cooling System

Soghe¹,

Andreini

2013

Journal of Turbomachinery

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“…These principles have driven the latest advances in impingement hole spacing [11], hole shaping [12] and separation distances [10] in ACC manifolds. Overall performance may be further improved by adding model fidelity, e.g.…”

Section: Literature Reviewmentioning

confidence: 99%

A Comparison of Single-Entry and Multiple-Entry Casing Impingement Manifolds for Active Thermal Tip Clearance Control

Dhopade¹,

Kirollos²,

Ireland³

et al. 2021

Preprint

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In this paper we compare using computational fluid dynamics the aerothermal performance of two candidate casing manifolds for supplying an impingement-actuated active tip clearance control system for an aero-engine high-pressure turbine. The two geometries are (a) single-entry: an annular manifold fed at one circumferential location; (b) multiple-entry: a casing manifold split into four annular sectors, each sector supplied separately from an annular ring main. Both the single-entry and multiple-entry systems analysed in this paper are idealised version of active clearance control systems in current production engines. Aerothermal performance is quantitatively assessed on the basis of the heat transfer coefficient distribution, driving temperature difference for heat transfer between the jet and casing wall, and total pressure loss within the high-pressure turbine active clearance control system. We predict that the mean heat transfer coefficient (defined with respect to the inlet temperature and local wall temperature) of the single-entry active clearance control system is 77% greater than the multiple-entry system; primarily because the coolant in the multiple-entry case picks up approximately 40 K of temperature from the ring main walls, and secondarily because the average jet Reynolds number of impingement holes in the single entry system is 1.2 times greater than in the multiple entry system. The multiple-entry system exhibits many local hot and cold spots, depending on the position of the transfer boxes, while the single-entry case has a more predictable aerothermal field across the system. The multiple-entry feed system uses an average of 20% of the total available pressure drop, while the feed system for the single-entry geometry uses only 2% of the total available pressure drop. From the aerothermal results of this computational study, and in consideration of holistic aero-engine design factors, we conclude that a single-entry system is closer to an optimal solution than a multiple-entry system.

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“…Comprehensive reviews on this field have been provided by Martin [15] and Han et al [16]. Some recent and very interesting contributions have been made by Ahmed and coworkers [5,6] who have performed some numerical simulations of the flow in a short tube section of an ACC system for a low pressure turbine. The length-to-diameter ratio of the sharp-edged cylindrical nozzles, ranging from 0.25 to 2, was also accounted for.…”

Section: Control Valvementioning

confidence: 99%

Aerothermal Analysis of a Turbine Casing Impingement Cooling System

Soghe

Facchini²,

Micio³

et al. 2012

International Journal of Rotating Machinery

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Heat transfer and pressure drop for a representative part of a turbine active cooling system were numerically investigated by means of an in-house code. This code has been developed in the framework of an internal research program and has been validated by experiments and CFD. The analysed system represents the classical open bird cage arrangement that consists of an air supply pipe with a control valve and the present system with a collector box and pipes, which distribute cooling air in circumferential direction of the casing. The cooling air leaves the ACC system through small holes at the bottom of the tubes. These tubes extend at about 180° around the casing and may involve a huge number of impinging holes; as a consequence, the impinging jets mass flow rate may vary considerably along the feeding manifold with a direct impact on the achievable heat transfer levels. This study focuses on the performance, in terms of heat transfer coefficient and pressure drop, of several impinging tube geometries. As a result of this analysis, several design solutions have been compared and discussed.

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Numerical Investigation of Heat Transfer and Pressure Drop Characteristics for Different Hole Geometries of a Turbine Casing Impingement Cooling System

Cited by 11 publications

References 0 publications

Numerical Characterization of Pressure Drop Across the Manifold of Turbine Casing Cooling System

Numerical Characterization of Pressure Drop Across the Manifold of Turbine Casing Cooling System

A Comparison of Single-Entry and Multiple-Entry Casing Impingement Manifolds for Active Thermal Tip Clearance Control

Aerothermal Analysis of a Turbine Casing Impingement Cooling System

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