Heat Transfer Coefficient Determination on 3D Geometries from Transient Thermochromic Liquid Crystal Experiments

Ryley, Joshua R.; McGilvray, Matthew; Gillespie, David R. H.

doi:10.2514/1.t5701

Cited by 4 publications

(3 citation statements)

References 17 publications

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“…Narrow band crystals also have much lower surface orientation dependency than wide band crystals which is crucial on a 3D geometry. A similar experimental approach is taken by Ryley et. al (2019) who recommend viewing angles kept within 70° to avoid intensity orientation dependency.…”

Section: Figure 2 Example Of Narrowband Liquid Crystal Response Appli...mentioning

confidence: 99%

Demonstration of high porosity cooling systems using novel Thermochromic Liquid Crystal approach

Wambersie,

Ireland

2023

European Conference on Turbomachinery Fluid Dynamics and Thermodynamics

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High porosity cooling systems have recently shown promise as a potential option for increasing turbine blade cooling effectiveness. To demonstrate the viability of this approach, a set of turbine blades with a double wall high porosity cooling scheme was manufactured from engine-grade materials. These were tested for metal effectiveness at steady state using a lowtemperature high-speed cascade with engine-representative conditions.Metal effectiveness values were obtained using a novel post-processing technique, based on the response of multiple narrow-band liquid crystals allowing for high-resolution in situ measurements.Results demonstrated the high cooling potential of such designs as well as their potential implementation within a double-walled system. The comparison between the measured metal effectiveness values to existing state of the art cooling designs suggests that the potential increase in cooling effectiveness exceeds 5-7% at existing mass flows or alternatively, allows for a 15-20% reduction in coolant mass flow for equivalent cooling effectiveness levels. KEYWORDSMETAL EFFECTIVENESS, TRANSPIRATION COOLING, HIGH POROSITY, DOUBLE WALL COOLING, TLCS NOMENCLATURE BR Blowing ratio D Film hole diameter (mm) h heat transfer coefficient (HTC) (W/m 2 .K) i Pixel relative intensity k Metal Conductivity (W/m.K) L Pressure surface length (mm) M* nondimensional mass flow rate .𝑚 ̇𝑐 Coolant mass flow rate PR Pressure Ratio

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Section: Figure 2 Example Of Narrowband Liquid Crystal Response Appli...mentioning

confidence: 99%

Demonstration of high porosity cooling systems using novel Thermochromic Liquid Crystal approach

Wambersie,

Ireland

2023

European Conference on Turbomachinery Fluid Dynamics and Thermodynamics

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“…Approaches such as the three dimensional Alternating Direction Implicit (ADI) method have been used to correct the output from the one dimensional solution [6], and corner corrections [5]. More recently, this has been superseded by full three dimensional analyses due to increased computational capacity [8].…”

Section: • Turbulence Modellingmentioning

confidence: 99%

“…Post-processing of the raw data can be undertaken using a variety of techniques including finite difference, analytical derivations [2] and impulse response methods [3]. Corrections for complex geometry exist [4][5][6] and transient FEA can be applied to truly 3D geometries [7,8].…”

Section: Introductionmentioning

confidence: 99%

Analytical Thermal Boundary Condition for Quasi-Transient Simulation of Internal Flow Experiments

Forsyth

Gillespie

McGilvray

2022

Journal of Thermophysics and Heat Transfer

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Transient thermochromic liquid crystal (TLC) experiments can provide high fidelity spatiallyresolved heat transfer data for complex geometries, particularly where infrared techniques cannot be applied. One challenge when applying transient methods to internal geometries is the local definition of the driving gas temperature. The transient nature of the streamwise driving gas temperature profile has led to comparisons with steady state computational fluid dynamics (CFD) being questioned. This paper explores simulating the temporal behaviour of transient TLC experiments directly. A novel technique is developed to account for differences in the gas and solid time scales, where surface temperature is calculated at each spatial location analytically from the surface heat flux using an impulse response method assuming one dimensional, semi-infinite conduction. Post-processing of the simulated surface temperature history is performed using the same method as experimentally, allowing for direct comparison. This analytical thermal boundary condition (ATBC) is applied to simulate a transient TLC experiment of a stationary super-scaled rib turbulated internal cooling passage in a gas turbine engine. Traditional steady state simulations were also performed with constant temporal and spatial temperature boundary conditions. Results show that calculations using the new ATBC and traditional steady state method give very similar Nusselt number distributions and mean values in relation to the experimental data, suggesting the larger discrepancy between simulations and the experiments is not the definition of the driving gas temperature. Analysis of transient variation of Nusselt number indicated brief highly localised maximum variations up to 40 %, though this was not found to significantly affect the mean values, and passage-averaged values converged to within 0.5 % of final value within 0.2 s.

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Deducing flux from single point temperature history when relative spatial variation of flux is prescribed

Buttsworth

2021

International Journal of Heat and Mass Transfer

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Heat Transfer Coefficient Determination on 3D Geometries from Transient Thermochromic Liquid Crystal Experiments

Abstract: A valuable new post-processing technique has been developed to enable the application of transient thermochromic liquid crystal experiments where lateral conduction is significant, and thus, cannot be treated as one-dimensional. This enables

Cited by 4 publications

References 17 publications

Demonstration of high porosity cooling systems using novel Thermochromic Liquid Crystal approach

Demonstration of high porosity cooling systems using novel Thermochromic Liquid Crystal approach

Analytical Thermal Boundary Condition for Quasi-Transient Simulation of Internal Flow Experiments

Deducing flux from single point temperature history when relative spatial variation of flux is prescribed

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