Modal Inverse Frequency Response Heat Transfer Analysis for Estimation of Machine Tool Transient Thermal Loads

2001 ◽  
Author(s):  
Youji Ma ◽  
Jingxia Yuan ◽  
Jun Ni
Keyword(s):  
Heat Transfer ◽  
Machine Tool ◽  
Temperature Measurement ◽  
Measurement Data ◽  
Heat Transfer Analysis ◽  
Thermal Loads ◽  
Thermal Errors ◽  
Machine Tool Structure ◽  
Transient Thermal ◽  
Modal Method

Abstract Thermal loads of internal and external sources cause thermal deformations of a machine tool structure and affect its accuracy. Software-based real-time error compensation method is an effective way to reduce the thermal errors. However, lack of knowledge of thermal loads impedes greater success. In this paper, a method of inverse heat transfer analysis is developed that, using temperature measurement data from multiple sensors mounted on a machine tool structure, the transient thermal loads of multiple heat sources can be estimated simultaneously. The method uses modal method and is carried out in frequency domain. The temperature measurement data are first transformed into frequency spectra through DFT. The modal method of inverse frequency response analysis is then used to obtain the thermal load spectra. Finally the thermal loads are recovered from their spectra through IDFT. The estimated thermal loads play crucial roles in estimating transient temperature fields and transient thermal errors of a machine tool structure. The issues of mode truncations and frequency truncations, and their effects on the efficiency and stability of the method are also discussed with simulation results. Finally, experimental results on a machining center column are presented.

Conjugate Heat Transfer Methodology for Thermal Design and Verification of Gas Turbine Cooled Components

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Lorenzo Winchler ◽  
Antonio Andreini ◽  
Bruno Facchini ◽  
Luca Andrei ◽  
Alessio Bonini ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Conjugate Heat Transfer ◽  
Cooling System ◽  
Measurement Data ◽  
Thermal Design ◽  
Heat Transfer Analysis ◽  
Internal Cooling ◽  
Cfd Analysis ◽  
Continuous Increase

Gas turbine design has been characterized over the years by a continuous increase of the maximum cycle temperature, justified by a corresponding increase of cycle efficiency and power output. In such way, turbine components heat load management has become a compulsory activity, and then, a reliable procedure to evaluate the blades and vanes metal temperatures is, nowadays, a crucial aspect for a safe components design. In the framework of the design and validation process of high pressure turbine cooled components of the BHGE NovaLTTM 16 gas turbine, a decoupled methodology for conjugate heat transfer prediction has been applied and validated against measurement data. The procedure consists of a conjugate heat transfer analysis in which the internal cooling system (for both airfoils and platforms) is modeled by an in-house one-dimensional thermo-fluid network solver, the external heat loads and pressure distribution are evaluated through 3D computational fluid dynamics (CFD) analysis and the heat conduction in the solid is carried out through a 3D finite element method (FEM) solution. Film cooling effect has been treated by means of a dedicated CFD analysis, implementing a source term approach. Predicted metal temperatures are finally compared with measurements from an extensive test campaign of the engine in order to validate the presented procedure.

scholarly journals Thermal Error Minimization of a Turning-Milling Center with Respect to its Multi-Functionality

2020 ◽  
Vol 14 (3) ◽  
pp. 475-483
Author(s):  
Martin Mareš ◽  
◽  
Otakar Horejš ◽  
Jan Hornych
Keyword(s):  
Machine Tool ◽  
Transfer Functions ◽  
Thermal Error ◽  
Error Reduction ◽  
Model Verification ◽  
Thermal Errors ◽  
Modeling Approach ◽  
Machine Tool Structure ◽  
Calibration Time

Achieving high workpiece accuracy is a long-term goal of machine tool designers. Many causes can explain workpiece inaccuracy, with thermal errors being the most dominant. Indirect compensation (using predictive models) is a promising thermal error reduction strategy that does not increase machine tool costs. A modeling approach using transfer functions (i.e., a dynamic method with a physical basis) has the potential to deal with this issue. The method does not require any intervention into the machine tool structure, uses a minimum of additional gauges, and its modeling and calculation speed are suitable for real-time applications that result in as much as 80% thermal error reduction. Compensation models for machine tool thermal errors using transfer functions have been successfully applied to various kinds of single-purpose machines (milling, turning, floor-type, etc.) and have been implemented directly into their control systems. The aim of this research is to describe modern trends in machine tool usage and focuses on the applicability of the modeling approach to describe the multi-functionality of a turning-milling center. A turning-milling center is capable of adequately handling turning, milling, and boring operations. Calibrating a reliable compensation model is a real challenge. Options for reducing modeling and calibration time, an approach to include machine tool multi-functionality in the model structure, model transferability between different machines of the same type, and model verification out of the calibration range are discussed in greater detail.

Inverse Heat Transfer Analysis of Porous Extended Surface Using Simplex Search Method

2013 ◽  
Author(s):  
Rohit Kumar Singla ◽  
Ranjan Das ◽  
Arka Bhowmik ◽  
Ramjee Repaka
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Temperature Measurement ◽  
Thermal Conditions ◽  
Search Method ◽  
Heat Transfer Analysis ◽  
Critical Parameters ◽  
Simplex Search ◽  
Simplex Search Method ◽  
Extended Surface

This work deals with the application of the Nelder-Mead simplex search method (SSM) to study a porous extended surface. At first, analytical expression for calculating the local temperature field has been derived using an implicit Runge-Kutta method. The heat transfer phenomenon is assumed to be governed by conductive, naturally convective and radiative heat transfer, whereas the diffusion of mass through the porous media is also taken into account. Then, using the SSM, critical parameters such as porosity, permeability, and thermal conductivities of the extended surface have been predicted for satisfying a prescribed temperature field. It is found that many alternative solutions can meet a given thermal requirement, which is proposed to offer the flexibility in selecting the material and regulating the thermal conditions. It is observed that the allowable error in the temperature measurement should be limited within 5%. It is also found that even with few temperature measurement points, very good reconstruction of the thermal field is possible using the SSM.

Heat Transfer Analysis of the Operation in Delayed Coking Coke Drum

2013 ◽  
Vol 448-453 ◽  
pp. 3277-3280
Author(s):  
Cheng Qing Lu ◽  
Nai Ming Wu ◽  
Kai Quan Yang
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Measurement Data ◽  
Heat Transfer Analysis ◽  
Element Analysis ◽  
Delayed Coking ◽  
Thermal Boundary Conditions ◽  
Temperature Change Rate ◽  
Coking Technology ◽  
Almost All

Delayed coking coke drum is the core equipment of delayed coking technology, which experiences almost all the thermal and mechanical loadings during operation. In this study, two coke drum finite element models have been created with four material models and the thermal boundary conditions are determined based on the temperature measurement data. Finite element analysis methods known as function loading and multiple steps analysis are used through the simulation. Temperature distributions and temperature variation curves of different nodes are then obtained by finite element heat transfer analysis. Numerical results show that temperature distribution is complex in the transition section and the water cooling stage has the highest temperature change rate.

Conjugate Heat Transfer Methodology for Thermal Design and Verification of Gas Turbine Cooled Components

2018 ◽  
Author(s):  
Lorenzo Winchler ◽  
Antonio Andreini ◽  
Bruno Facchini ◽  
Luca Andrei ◽  
Alessio Bonini ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Gas Turbine ◽  
Conjugate Heat Transfer ◽  
Cooling System ◽  
Measurement Data ◽  
Thermal Design ◽  
Heat Transfer Analysis ◽  
Cfd Analysis ◽  
3D Fem ◽  
Continuous Increase

Gas turbine design has been characterized over the years by a continuous increase of the maximum cycle temperature, justified by a corresponding increase of cycle efficiency and power output. In such way turbine components heat load management has become a compulsory activity and then, a reliable procedure to evaluate the blades and vanes metal temperatures, is, nowadays, a crucial aspect for a safe components design. In the framework of the design and validation process of HPT (High Pressure Turbine) cooled components of the BHGE NovaLT™ 16 gas turbine, a decoupled methodology for conjugate heat transfer prediction has been applied and validated against measurement data. The procedure consists of a conjugate heat transfer analysis in which the internal cooling system (for both airfoils and platforms) is modeled by an in-house one-dimensional thermo-fluid network solver, the external heat loads and pressure distribution are evaluated through 3D CFD analysis and the heat conduction in the solid is carried out through a 3D FEM solution. Film cooling effect has been treated by means of a dedicated CFD analysis, implementing a source term approach. Predicted metal temperatures are finally compared with measurements from an extensive test campaign of the engine, in order to validate the presented procedure.

Procedure for Calculation of Component Thermal Loads for Running Clearances of Heavy-Duty Gas Turbines

2012 ◽  
Author(s):  
Luca Bozzi ◽  
Andrea Perrone ◽  
Luca Giacobone
Keyword(s):  
Heat Transfer ◽  
Gas Turbines ◽  
Fem Analysis ◽  
Operating Conditions ◽  
Computational Method ◽  
Heat Transfer Analysis ◽  
Thermal Loads ◽  
Transient Conditions ◽  
Analysis And Evaluation ◽  
Turbine Casing

The energy market development in the last decade has been influenced by several driving factors. To meet the strict customers’ requirements (related to low emissions, flexibility and high performances), operate gas turbine plants safely over a variety of off-design operating conditions has been fundamental. Accordingly, accurate evaluation of running clearances in stationary and transient conditions plays a significant role. On the other hand, the study of heat transfer in turbo-machinery is a fundamental activity to study the implications of off-design operating on components’ lifing. Focus of the paper is the analysis of variations of components’ wall temperature and clearances due to the fluctuation of thermal loads acting on gas turbines components during operation. The study is divided into two main sections: heat transfer analysis allows evaluating thermal loads and then a FEM analysis is performed in order to calculate the radial and axial clearances between rotor components and casing. Thermal loads are obtained by a computational method based on heat transfer correlations. Parametric curves have been developed to calculate variations of thermal loads in transient conditions from steady-state data obtained by the correlative computational tool. The two procedures for heat transfer analysis and evaluation of clearances have been validated against experimental data in several operating conditions. In particular, relative and absolute movements of rotor and turbine casing have been measured by means of proxy-meter probes located into the turbine bearing casing.

Application of CFD to Solve Difficult Industry Thermal Stress Problems

2010 ◽  
Author(s):  
David J. Dewees
Keyword(s):  
Heat Transfer ◽  
Thermal Stress ◽  
Stress Analysis ◽  
Temperature Measurement ◽  
Temperature Gradients ◽  
Heat Transfer Analysis ◽  
Thermal Stress Analysis ◽  
Standard Heat ◽  
Computational Fluid Dynamics Cfd ◽  
Heat Transfer Correlations

Temperature variation is the source of load in pure thermal stress analysis; thus, meaningful prediction of temperatures in a structure is critical to analysis success. Temperature measurement and standard heat transfer correlations should be the basis of the majority of heat transfer analysis. However, there is a class of problems where temperature measurement is not possible or feasible and standard heat transfer correlations are not applicable. For cases such as these, computational fluid dynamics (CFD) provides a valuable tool to better assess the fluid/thermal behavior in complex configurations, and thus the resulting temperature gradients within a structure. Several practical examples that illustrate the value of CFD in thermal stress analysis are detailed in this paper.

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