共查询到20条相似文献,搜索用时 0 毫秒
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变几何域的表面热流反演是一类特殊的热传导逆问题,在再入飞行器烧蚀型防热材料的表面热流反演中具有工程实用价值.本文首先对变几何域传热的正问题计算方法进行了校核验证,然后建立了求解变几何域表面热流反演问题的顺序函数法和共轭梯度法;给出了这两种反演方法的基本思想和算法推导,并针对典型算例进行了仿真.结果表明:两种反演方法都能计算出较好的反演结果,并且算法受测量噪声的影响较小,具有较好的鲁棒性;反演算法能适应不同的几何域变化函数,但几何域变化量的测量误差在表面热流的反演结果中会有较为直接的反映. 相似文献
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J. Taler 《Heat and Mass Transfer》1992,27(8):505-513
A family of numerical methods for determining the space-and time-variable heat transfer coefficient, based on experimentally acquired interior temperature-time data, is presented. Newton-type methods are utilized to compute simultaneously the unknown heat transfer coefficient components. To reduce the influence of random errors in the measurement data on the estimated heat transfer coefficients, the noisy data are smoothed using least squares approximation by cubic splines. Three test examples using experimental and random simulated data are used to illustrate the computation efficiency and generality of the present methods. 相似文献
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J. M. Gu 《Heat and Mass Transfer》1993,28(3):117-122
This paper develops reducing deviation method to solve inverse heat conduction problem with nonuniform heat flux density on boundary. When the thermocouple is placed a bit far from the boundary, there is no problem on non-convergence in this method. A calculation example is given. 相似文献
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CHAOS-REGULARIZATION HYBRID ALGORITHM FOR NONLINEAR TWO-DIMENSIONAL INVERSE HEAT CONDUCTION PROBLEM 总被引:2,自引:0,他引:2
IntroductionAsakindofimportantthermalcharacteristicsofthematerial,thermalconductivitymustbedeterminedtomakequantificationalanalysisoftemperaturefield .Ithasbeentakendueattentiontoestimatethethermalconductivityfrominnerand/orboundarytemperaturemeasureme… 相似文献
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Graetz problem in curved pipes with uniform wall heat flux 总被引:1,自引:0,他引:1
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The unsteady, compressible, Reynolds-averaged Navier-Stokes equations are solved numerically for an oblique shock-wave-induced turbulent boundary layer sepration. For the freestream Mach number 6 and the freestream Reynolds number 66·1 × 106 m?1, a time-dependent computation is performed, using MacCormack's explicit-implicit finite difference method with 82 × 42 grid points. A two-layer eddy viscosity turbulence model is employed in conjunction with a relaxation modification. Comparisons of the mean wall pressure and the mean heat transfer coefficient with the available experimental results are made and the evaluation of unsteady data for surface pressure and heat flux fluctuations is presented. It is found that the fluctuations in heat flux have qualitatively the same features as those of wall pressure but are different quantitatively. 相似文献
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Theoretical investigations were performed on the developed laminar flow and convective heat transfer characteristics for incompressible
gases flow through rectanglar micropassages with constant wall heat flux. Mathematical models were proposed for considering
the change in viscosity and thermal conductivity of gas in the wall-adjacent region from the kinetic theory. The dimensionless
velocity distribution and corresponding pressure drop, the dimensionless temperature distribution and corresponding heat transfer
characteristics were both simulated numerically, and the results were compared to other report simulations [10–12] with brief
discussions. 相似文献
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A nonlinear inverse problem utilizing the Conjugate Gradient Method (CGM) of minimization is used successfully to estimate the temporally and circumferentially varying thermal contact conductance of a plate finned-tube heat exchanger by reading the simulated transient temperature measurement data from the thermocouples located on the plate. The thermal properties of the fin and tube are assumed to be functions of temperature, and this makes the problem nonlinear. It is assumed that no prior information is available on the functional form of the unknown thermal contact conductance in the present study, thus, it is classified as the function estimation in the inverse calculation. The accuracy of the inverse analysis is examined by using the simulated temperature measurements. Finally the inverse solutions with and without the consideration of temperature-dependent thermal properties are compared. Results show that when the nonlinear inverse calculations are performed an excellent estimation on the thermal contact conductance can be obtained with any arbitrary initial guesses within a couple of minute's CPU time on a HP-730 workstation. 相似文献
10.
The extended Graetz problem with piecewise constant wall heat flux for laminar and turbulent flows inside concentric annuli 总被引:1,自引:0,他引:1
In the present paper, the heat transfer characteristics in the thermal entrance region of concentric annuli have been analysed for laminar and turbulent internal flow. Axial heat conduction effects in the fluid have been taken into account. The present paper shows an exact analytical solution for the problem of a piecewise uniform wall heat flux. The obtained analytical solution for the extended Graetz problem is as simple and efficient to compute as the related solution of the parabolic problem. The obtained results show the effect of axial heat conduction in the fluid for a semi-infinite heated section as well as for a finite length of the heated section. It is shown, that for a finite length of the heated section, axial heat conduction effects might be important even for higher Peclet number. 相似文献
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I. Yu. Tsvelodub 《Journal of Applied Mechanics and Technical Physics》2007,48(5):708-711
An elastic plate with a physically nonlinear inclusion of an arbitrary shape is considered. This plate is subjected to pure
bending under the action of transverse forces and bending moments applied at the external boundary of the plate. There are
no loads distributed over the surface. The problem of finding external actions that provide a necessary uniform moment state
in the inclusion, i.e., prescribed constant moments and curvatures, is formulated and solved.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 5, pp. 104–107, September–October, 2007. 相似文献
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A. Ya. Kuzin 《Journal of Applied Mechanics and Technical Physics》1995,36(1):98-104
Tomsk. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, No. 1, pp. 106–112, January–February, 1995. 相似文献
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The Airy jet is a wall-bounded flow belonging to the similarity class of the well known free jet but, in contrast to the latter, its far field behavior is an algebraically decaying rotational flow. The present paper investigates the thermal characteristics of the Airy jet over a wall with prescribed constant heat flux. The scaling behavior found for small and large values of the Prandtl number is compared to those obtained earlier for (a) the case of a wall with prescribed constant temperature and for (b) the case of a preheated Airy jet adjacent to an insulated wall. 相似文献
18.
热传导反问题求解在工程领域具有重要的应用价值.本文发展数据驱动模型识别了管道内壁几何形状和皮肤肿瘤生长参数等热传导反问题.在管道内壁几何形状识别问题中,首先采用随机生成模型结合有限元法求解热传导正问题,并采用有效导热系数转化的思想,建立机器学习模型,求解了测点温度与有效导热系数之间的抽象映射关系,进而实现管道内壁几何形... 相似文献
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N. M. AL-Najem 《Heat and Mass Transfer》1997,33(3):233-240
The unknown surface conditions in composite media is estimated by minimizing the nonlinear least squares error between the
computed and measured temperatures over the whole time domain. This approach shown to be stable, efficient and accurate. The
unknown surface conditions are assumed to have an abrupt change at unknown time. A sensitivity analysis is conducted to learn
more insight into the nature of difficulties that can be encountered in the estimation of the parameters associated with the
inverse problem. The stability and accuracy of the method is demonstrated by several numerical examples which provide very
strict test conditions.
Received on 7 March 1997 相似文献
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In this study, a method of chemical cooling is put forward, that is, C–CO2 endothermic reaction is applied to instantaneous heat removal under high heat flux. A method in which theoretical research is in combination with numerical simulation is used to study C–CO2 endothermic reaction. In comparison with the theoretically computational results, numerical code is validated. A high heat flux of 500 W/cm2 is applied to the research of the heat dissipation characteristics of C–CO2 endothermic reaction. The theoretical calculation results show that, under a certain temperature and pressure condition, the C–CO2 chemical endothermic reaction could remove heat from the system promptly; the product CO could be used as a supplementary medium of power source for cycling. Compared with water phase change, the C–CO2 endothermic reaction appears to have stronger heat removal ability. “Species Transport” module in FLUENT was adopted to simulate the reaction. Under the same temperature and pressure condition, the numerical simulation results are found to be well congruous with theoretical results. The C–CO2 endothermic reaction could make a high temperature in the reaction system due to a high heat flux reduce to a low temperature (below zero) promptly. The heat removal and reaction time are in consistence with theoretical calculation. 相似文献