排序方式: 共有21条查询结果,搜索用时 31 毫秒
1.
Philippe Nika Yannick Bailly Michel De Labachelerie Jean Claude Jeannot Jacques De Lallee 《Nanoscale and Microscale Thermophysical Engineering》2013,17(4):301-325
The miniaturization of refrigerating systems represents a very current scientific and technical challenge to improve the performances of numerous electronic components. This work presents a global approach to the problem and suggests studying the cooling by means of small channels filled with an oscillating gas: the double inlet pulse tube refrigerator (DIPTR). A great level of miniaturization based on the technology of carving silicon is exposed. This study proposes to apply an electric analogy for modeling both hydrodynamic and thermal phenomena. Considering the complexity of the theoretical problem including mechanical, thermal, thermodynamical, and acoustic considerations, the authors take care to summarize the main governing equations in a particular form so any scientific engineer could understand the DIPTR principle. 相似文献
2.
Karthik Kashinath Santosh Hemchandra Matthew P. Juniper 《Combustion and Flame》2013,160(12):2856-2865
When a premixed flame is placed within a duct, acoustic waves induce velocity perturbations at the flame’s base. These travel down the flame, distorting its surface and modulating its heat release. This can induce self-sustained thermoacoustic oscillations. Although the phase speed of these perturbations is often assumed to equal the mean flow speed, experiments conducted in other studies and Direct Numerical Simulation (DNS) conducted in this study show that it varies with the acoustic frequency. In this paper, we examine how these variations affect the nonlinear thermoacoustic behaviour. We model the heat release with a nonlinear kinematic G-equation, in which the velocity perturbation is modelled on DNS results. The acoustics are governed by linearised momentum and energy equations. We calculate the flame describing function (FDF) using harmonic forcing at several frequencies and amplitudes. Then we calculate thermoacoustic limit cycles and explain their existence and stability by examining the amplitude-dependence of the gain and phase of the FDF. We find that, when the phase speed equals the mean flow speed, the system has only one stable state. When the phase speed does not equal the mean flow speed, however, the system supports multiple limit cycles because the phase of the FDF changes significantly with oscillation amplitude. This shows that the phase speed of velocity perturbations has a strong influence on the nonlinear thermoacoustic behaviour of ducted premixed flames. 相似文献
3.
Verification of the applicability of the linearized thermoacoustic theory proposed in 1988 by Swift, J. Acoust. Soc. Am., 84 , (4), 1145–1180, to an acoustic- resonance tube refrigerator and discussions on the advanced linearized theory were conducted through a comparison with the measured temperature distribution along the stack in a simulated acoustic-resonance tube. The measured temperature in all cases of various stack configurations such as stack plate spacing and length showed an almost linear distribution along the stack, while Swift's linearized theory gave a curved distribution with relatively large deviation from experimental data. Eddy diffusivity and/or steady streaming effects excited by sound waves were taken into account in the linearized model, and the effects of these terms on the prediction of temperature distribution were examined. The agreement between theory and experiment was markedly improved by the introduction of steady streaming. This provided a guideline for the construction of an advanced linearized theory. © 1999 Scripta Technica, Heat Trans Jpn Res, 27(8): 551–567, 1998 相似文献
4.
开式循环热声原理研究 总被引:1,自引:0,他引:1
稳定的开发流与热声循环的振荡流进行叠加,使开环流既是过程介质又是工作介质直接参与热声循环,从而构成开式热声系统,它具有与传统热声系统不同的热声作用机理。在开发式循环热声系统中,热声板叠中的温度分布和热流分布均发生有意义的改变。开式的循环声系统具有结构简单可靠、成本低和热效率高等特点,因而具有十分广阔的热声研究与应用前景。本文主要介绍了开式循环热声系统的工作机理和其网络模型。 相似文献
5.
6.
热声现象是放热过程和声学脉动之间的一种正向的相互激励,利用热声效应的Rijke型燃烧器具有高燃烧效率,低过剩空气系数等特点,本文探讨了开发新型燃烧装置需要解决的问题,以及国内研制新型燃烧器的作用和意义。 相似文献
7.
8.
变负载法研究热声发动机的声功输出特性 总被引:3,自引:0,他引:3
为提高热声发动机的驱动能力并为有效负载的设计提供参考,对一台行波热声发动机的声功输出特性进行了研究.应用变负载法,对该热声发动机的声功输出进行了精确测量.分析得到声功输出与热声发动机压比、加热功率和加热温度之间的相互影响关系.通过改变阀门开度和气库容积大小,分析了负载的阻力和空体积对声功输出和系统热效率的影响.结果表明,在输入功率为2.3 kW,充气压力为2.6 MPa,工作频率为51 Hz时,该热声发动机获得了122 W的最大声功输出.为设计与热声发动机系统具有良好匹配的热声制冷机及其他有效负载奠定了基础. 相似文献
9.
10.