Analýza nejistot inverzního problému vedení tepla ve dvou prostorových souřadnicích
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Authors
Iftikhar, Muhammad Yazman
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Mark
E
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Vysoké učení technické v Brně. Fakulta strojního inženýrství
Abstract
This dissertation examines an inverse heat conduction problem (IHCP) approach to approximate the transient heat transfer coefficient (HTC) distribution on the cooling surface of a high-pressure die casting (HPDC) die insert. We design a synthetic numerical experiment to produce internal temperature data, which is used as input for the inverse analysis. A derivative-free technique of optimization, BOBYQA which is applied via the the NLOPT library is employed to reconstruct the HTC. The HTC are spatially discretized at the thermocouple projection points by the inverse model and linear interpolation is used to approximate the continuous distribution. A strong agreement of viability is manifested against reference data which confirms the accuract of the method. An investigation of sensitivity revealed that even small perturbations in the positions of thermocouples heavily impact the reconstructed HTC. This highlights the significance of the placement of sensors. The robustness of the method is further supported by the analysis of pointwise relative error where local errors are very low. Even though regularization was not performed, it potential to improve stability is discussed as a further enhancement. Altogether, this work provides a practical and efficient inverse method for thermal diagnostics in HPDC, resulting in an enhanced process modeling and experimental design.
This dissertation examines an inverse heat conduction problem (IHCP) approach to approximate the transient heat transfer coefficient (HTC) distribution on the cooling surface of a high-pressure die casting (HPDC) die insert. We design a synthetic numerical experiment to produce internal temperature data, which is used as input for the inverse analysis. A derivative-free technique of optimization, BOBYQA which is applied via the the NLOPT library is employed to reconstruct the HTC. The HTC are spatially discretized at the thermocouple projection points by the inverse model and linear interpolation is used to approximate the continuous distribution. A strong agreement of viability is manifested against reference data which confirms the accuract of the method. An investigation of sensitivity revealed that even small perturbations in the positions of thermocouples heavily impact the reconstructed HTC. This highlights the significance of the placement of sensors. The robustness of the method is further supported by the analysis of pointwise relative error where local errors are very low. Even though regularization was not performed, it potential to improve stability is discussed as a further enhancement. Altogether, this work provides a practical and efficient inverse method for thermal diagnostics in HPDC, resulting in an enhanced process modeling and experimental design.
This dissertation examines an inverse heat conduction problem (IHCP) approach to approximate the transient heat transfer coefficient (HTC) distribution on the cooling surface of a high-pressure die casting (HPDC) die insert. We design a synthetic numerical experiment to produce internal temperature data, which is used as input for the inverse analysis. A derivative-free technique of optimization, BOBYQA which is applied via the the NLOPT library is employed to reconstruct the HTC. The HTC are spatially discretized at the thermocouple projection points by the inverse model and linear interpolation is used to approximate the continuous distribution. A strong agreement of viability is manifested against reference data which confirms the accuract of the method. An investigation of sensitivity revealed that even small perturbations in the positions of thermocouples heavily impact the reconstructed HTC. This highlights the significance of the placement of sensors. The robustness of the method is further supported by the analysis of pointwise relative error where local errors are very low. Even though regularization was not performed, it potential to improve stability is discussed as a further enhancement. Altogether, this work provides a practical and efficient inverse method for thermal diagnostics in HPDC, resulting in an enhanced process modeling and experimental design.
Description
Keywords
Inverse heat conduction problem (IHCP), Heat transfer coefficient (HTC), High-pressure die casting (HPDC), Numerical experiment, Thermocouple sensitivity and placement, BOBYQA optimization algorithm, NLOPT optimization library, Derivative-free optimization, Thermal boundary condition reconstruction, Transient heat conduction, Finite volume method (FVM), Computational fluid dynamics (CFD), k-w SST turbulence model, Temperature measurement uncertainty, Sensor misplacement effects, Thermal diagnostics, Optimization under uncertainty, Jet cooling in die casting, Boundary condition discretization, Regularization techniques, Sensitivity analysis, Thermal process modeling, Inverse modeling, Trust-region methods, Optimization with bound constraint., Inverse heat conduction problem (IHCP), Heat transfer coefficient (HTC), High-pressure die casting (HPDC), Numerical experiment, Thermocouple sensitivity and placement, BOBYQA optimization algorithm, NLOPT optimization library, Derivative-free optimization, Thermal boundary condition reconstruction, Transient heat conduction, Finite volume method (FVM), Computational fluid dynamics (CFD), k-w SST turbulence model, Temperature measurement uncertainty, Sensor misplacement effects, Thermal diagnostics, Optimization under uncertainty, Jet cooling in die casting, Boundary condition discretization, Regularization techniques, Sensitivity analysis, Thermal process modeling, Inverse modeling, Trust-region methods, Optimization with bound constraint.
Citation
IFTIKHAR, M. Analýza nejistot inverzního problému vedení tepla ve dvou prostorových souřadnicích [online]. Brno: Vysoké učení technické v Brně. Fakulta strojního inženýrství. 2025.
Document type
Document version
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Language of document
en
Study field
bez specializace
Comittee
doc. Ing. Luděk Nechvátal, Ph.D. (předseda)
prof. RNDr. Josef Šlapal, CSc. (místopředseda)
doc. Ing. Petr Tomášek, Ph.D. (člen)
doc. Ing. Jiří Šremr, Ph.D. (člen)
prof. RNDr. Miloslav Druckmüller, CSc. (člen)
Prof. Bruno Rubino, Ph.D. (člen)
Assoc. Prof. Matteo Colangeli, PhD. (člen)
Date of acceptance
2025-06-18
Defence
The student presented their Master's thesis to the examination committee. The secretary of the committee read aloud the evaluation report of the thesis supervisor. The opponent, who was present in person, read her review. Following this, the student responded to the opponent’s questions. The opponent expressed satisfaction with the student’s answers.
Result of defence
práce byla úspěšně obhájena
Document licence
Standardní licenční smlouva - přístup k plnému textu bez omezení