Accessing quantitative heat transfer with Temperature Decline Thermography

Hoesslin, Stefan von; Gruendmayer, Juergen; Zeisberger, Andreas; Kähler, Christian J.

doi:10.1016/j.expthermflusci.2019.06.004

Cited by 5 publications

(2 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For transient techniques, the rapid heating or cooling of a specimen is recorded, and the heat transfer coefficient is calculated according to analytical or numerical models of the specimen. Metzger et al [5] recorded the transient heat up of an aluminum block, and von Hoesslin et al [14,19,20] recorded the temperature decline of a low conductivity coating after exposure to a high-energy laser pulse.…”

Section: State Of the Artmentioning

confidence: 99%

Heat transfer and film cooling measurements on aerodynamic geometries relevant for turbomachinery

et al. 2021

View full text Add to dashboard Cite

A measurement technique for recording convective heat transfer coefficient and adiabatic film cooling effectiveness in demanding environments with highly curved surfaces and limited optical access, such as turbomachinery, is presented. Thermography and tailor-made flexible heating foils are used in conjunction with a novel multistep calibration and data reduction method. This method compensates for sensor drift, angle dependence of surface emissivity and window transmissivity, heat flux inhomogeneity, and conductive losses. The 2D infrared images are mapped onto the 3D curved surfaces and overlapped, creating surface maps of heat transfer coefficient and film cooling effectiveness covering areas significantly larger than the window size. The measurement technique’s capability is demonstrated in a sector-cascade test rig of a turbine center frame (TCF), an inherent component of modern two-spool turbofan engines. The horseshoe vortices were found to play a major role for the thermal integrity of turbine center frames, as they lead to a local increase in heat transfer, and at the same instance, to a reduction of film cooling effectiveness. It was also found that the horseshoe vortices lift off from the curved surface at 50% hub length, resulting in a pair of counter-rotating vortices. The measurement technique was validated by comparing the data against flat plate correlations and also by the linear relation between temperature difference and heat flux. This study is complemented with an extensive error and uncertainty analysis. Article highlights This paper presents an accurate measurement technique for heat transfer and film cooling on 3D curved surfaces with limited optical access using flexible tailor-made heating foils, infrared thermography and a high-fidelity multistep calibration process. Graphical abstract

show abstract

Section: State Of the Artmentioning

confidence: 99%

Heat transfer and film cooling measurements on aerodynamic geometries relevant for turbomachinery

et al. 2021

View full text Add to dashboard Cite

show abstract

“…The obtained measurement data showed good agreement with the theoretical values. [3] Scholars mainly optimize the heat transfer coefficient from two aspects: measurement methods and measurement tools. [4,5] However, the heat transfer coefficient is influenced by many factors, such as the quenching medium type, [6] surface condition, [7] surface shape, [8] and stirring intensity.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation and Experimental Research on the Quenching Process of 1045 Steel Based on Thermo–Fluid–Solid Coupling Model

Deng

Huo

2023

steel research int.

View full text Add to dashboard Cite

In the numerical simulation research on quenching, the heat transfer coefficient is an important input parameter. However, owing to its complexity and various influencing factors, the measured results are not universal and will significantly increase the simulation complexity and error. This article proposes a new numerical simulation method for quenching processes by extending the simulation domain and introducing the coupled heat exchange between the liquid quenching medium and workpiece, replacing the role of the heat transfer coefficient in the numerical simulation. The method is validated through experimental studies on 1045 steel rod quenched in water, with the maximum relative errors of the simulation results compared to the experimental results being 3.6%, 9%, and 5.1% for hardness, cooling curve, and residual stress, respectively. Furthermore, the article investigates the effect of different flow parameters of quenching media on the quenching effect. Under the studied conditions, the 1045 steel rod has the lowest risk of cracking and the highest hardness value when quenched in water at 50°C. The proposed method improves the universality and convenience of numerical simulation for the quenching process. and can be used to guide the formulation of quenching process parameters when the heat transfer coefficient is unknown.This article is protected by copyright. All rights reserved.

show abstract