Modeling of the Heat Flux for Multi-Hole Cooling Applications

Cottin, Guillaume; Laroche, Emmanuel; Savary, Nicolas; Millan, Pierre

doi:10.1115/gt2011-46330

Cited by 9 publications

(12 citation statements)

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“…It may also have consequences regarding the thermal equilibrium of the plate by modifying the mixing between cold and hot gas as well as the relative strengths of the conduction (exchange through the solid plate) and the convection (fluid going through the holes) heat transfers. According to Cottin [17], the heat flux transmitted by conduction within the hole is as large as 37% of the total heat flux (convection and conduction) in the case of the LARA experiment of Miron [53] where M = 3.6 and J = 13; on the contrary, Florenciano [25] found that it was only 8% of the total heat flux in a flow regime corresponding to M = 8.4 and J = 31.…”

Section: DXmentioning

confidence: 99%

Low order modeling method for assessing the temperature of multi-perforated plates

Bizzari

Lahbib

Dauptain

et al. 2018

International Journal of Heat and Mass Transfer

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A low-order model is proposed to predict the temperature of a multi-perforated plate from an unresolved adiabatic computation. Its development relies on the analysis of both an adiabatic and a conjugate heat transfer wall resolved large eddy simulation of an academic multi-perforated liner representative of the cooling systems used in combustion chambers of actual aero-engines. These two simulations show that the time averaged velocity field is marginally modified by the coupling with the heat diffusion in the perforated plate when compared to the adiabatic case. This gives rise to a methodology to assess the wall temperature from an unresolved adiabatic computation. It relies on heat transfer coefficients from referenced correlations as well as a mixing temperature relevant to the flow in the injection region where the cold micro-jets mix with the hot outer flow. In this approach, a coarse mesh simulation using an homogeneous adiabatic model for the aerodynamics of the flow with effusion is post-processed to provide a low cost alternative to conjugate heat transfer computations based on hole resolved meshes. The model is validated on an academic test case and successfully applied to a real industrial combustion chamber.

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Section: DXmentioning

confidence: 99%

Low order modeling method for assessing the temperature of multi-perforated plates

Bizzari

Lahbib

Dauptain

et al. 2018

International Journal of Heat and Mass Transfer

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“…This correction is employed in the context of steady-state RANS analy ses and can be theoretically applied to every isotropic turbulence model. Bianchini et al [8] introduced a comparison between most used general purpose models and specific treatments developed for film cooling applications [21,23,24] showing that the best match with experimental evidence is achieved for film cooling flows in combination with the k-w shear-stress transport (SST) model.…”

Section: Introductionmentioning

confidence: 97%

“…From a numerical perspective, computational analysis of effu sion systems has proved to be quite challenging due to the high computational cost, related to the large of number of holes com posing the array and to the relatively high pitch to diameter ratio, and simplified modeling deficiency which are characteristic of the jet-in-cross flow scheme [8,19,20] (i.e., overprediction of penetra tion and underestimation of lateral spreading). For these reasons, only recently a proper and effective validation could be performed against experimental data at engine relevant conditions [6,21], These simulations relies on nonconventional turbulence modeling specifically constructed for film cooling phenomena to overcome the above mentioned deficiencies of standard RANS models. Such approach, which consists in a correction of near wall turbulence in case of jet-in-cross flow, is derived from Bergeles's idea of a tensorial definition of eddy viscosity [22] which can be augmented in the stream-span components by means of a doping factor calcu lated algebraically as a function of near wall distance [23].…”

Section: Introductionmentioning

confidence: 99%

Investigation on the Effect of a Realistic Flow Field on the Adiabatic Effectiveness of an Effusion-Cooled Combustor

Andrei

Andreini

Bianchini

et al. 2015

Journal of Engineering for Gas Turbines and Power

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Effusion cooling represents the state of the art of liner cooling technology for modern combustors. This technique consists of an array of closely spaced discrete film cooling holes and contributes to lower the metal temperature by the combined protective effect of coolant film and heat removal through forced convection inside each hole. Despite many efforts reported in literature to characterize the cooling performance of these devices, detailed analyses of the mixing process between coolant and hot gas are difficult to per form, especially when superposition and density ratio effects as well as the interaction with complex gas side flow field become significant. Furthermore, recent investigations on the acoustic properties of these perforations pointed out the challenge to maintain optimal cooling performance also with orthogonal holes, which showed higher sound absorption. The objective of this paper is to investigate the impact of a realistic flow field on the adiabatic effectiveness performance of effusion cooling liners to verify the findings available in literature, which are mostly based on effusion flat plates with aligned cross flow, in case of swirled hot gas flow. The geometry consists of a tubular combustion chamber, equipped with a double swirler injection system and characterized by 22 rows of cooling holes on the liner. The liner cooling system employs slot cooling as well: its interactions with the cold gas injected through the effusion plate are investigated too. Taking advantage of the rotational periodicity of the effusion geometry and assuming axisymmetric conditions at the combustor inlet, steady state RANS calculations have been performed with the commercial code ansys® CFX simulating a single circumferential pitch. Obtained results show how the effusion perforation angle deeply affects the flowfield around the corner of the combustor, in particular, with a strong reduction of slot effectiveness in case o f 90deg angle value.

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“…A first attempt to extend the concept of directional eddy viscosity to other turbulence models was carried out by Cottin et al [55] where the idea of Bergeles was implemented in a SST k − ω model with a benchmarking on a typical combustor liner effusion cooling geometry. Further contribution to this family of models comes from Li et al [56] where a set of general purpose shape functions obtained by higher order computations are used in the tensorial definition of eddy viscosity.…”

Section: Jet In Crossflowmentioning

confidence: 99%

“…Cottin et al [55]. It is implemented in OpenFOAM R code and ANSYS R CFX solver using the same source terms reported in Eq.…”

Section: Implementation In Two-layer Modelmentioning

confidence: 99%

Film Cooling Modelling for Gas Turbine Nozzles and Blades: Validation and Application

Andrei

Innocenti

Andreini

et al. 2015

Volume 5B: Heat Transfer

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The use of Computational Fluid Dynamics (CFD) for modern turbine blade design requires the accurate representation of the effect of film cooling. However, including complete cooling hole discretization in the computational domain requires a substantial meshing effort and leads to a drastic increase in the computing time. For this reason, many efforts have been made to develop lower order approaches aiming at reducing the number of mesh elements and therefore computational resources. The simplest approach models the set of holes as a uniform coolant injection, but it does not allow an accurate assessment of the interaction between hot gas and coolant. Therefore higher order models have been developed, such as those based on localized mass sources in the region of hole discharge. It is here proposed an innovative injection film cooling model (FCM), embedded in a CFD code, to represent the effect of cooling holes by adding local source terms at the hole exit in a delimited portion of the domain, avoiding the meshing process of perforations. The goal is to provide a reliable and accurate tool to simulate film-cooled turbine blades and nozzles without having to explicitly mesh the holes. The validation campaign of the proposed model is composed of two phases. During the first one, results obtained with the film cooling model are compared to experimental data and to numerical results obtained with the full meshing of the cooling holes on a series of test cases, ranging from single row to multi row flat plate, at varying coolant conditions (in terms of blowing and density ratio). Though details of the flow structure downstream of the holes cannot be perfectly captured, this method allows an accurate prediction of the overall flow and performance modifications induced by the presence of the cooling holes, with a strong agreement to complete hole discretization results. In the second phase, a complete film-cooled vane test case has been studied, in order to consider a real injection system and flow conditions. In this case, film cooling model predictions are compared to an in-house developed correlative approach and full CHT 3D-CFD results. Finally, a comparison between film cooling model predictions and experimental data was performed on an actual nozzle of a GE Oil & Gas heavy-duty gas turbine as well, in order to prove the feasibility of the procedure. The presented film cooling model proved to be a feasible and reliable tool to evaluate adiabatic effectiveness, simplifying the design phase avoiding the meshing process of perforations. Also, refining the mesh near the hole exit, FCM results well approximate the solution coming from a full CHT calculation.

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Modeling of the Heat Flux for Multi-Hole Cooling Applications

Cited by 9 publications

References 0 publications

Low order modeling method for assessing the temperature of multi-perforated plates

Low order modeling method for assessing the temperature of multi-perforated plates

Investigation on the Effect of a Realistic Flow Field on the Adiabatic Effectiveness of an Effusion-Cooled Combustor

Film Cooling Modelling for Gas Turbine Nozzles and Blades: Validation and Application

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