共查询到19条相似文献,搜索用时 156 毫秒
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针对气-液双作用行波热声发动机结构参数不一致性对系统热声转换特性的影响进行了数值模拟分析,分别讨论了回热器长度、液体活塞摩擦阻力以及液体活塞质量不对称的情况下,系统热声转换特性的变化。计算结果表明,仅改变一个基本单元的一个特定的结构参数时,整个气-液双作用行波热声发动机性能参数均发生改变,并且表现出不对称性。系统结构参数的不一致性对体积流率、压力振幅、相位以及气体温度的沿程分布均有明显影响。回热器产生的净声功率受结构参数不对称性影响显著,甚至可能出现某一基本单元回热器不产生声功率或消耗声功率的情况,值得重点关注。 相似文献
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热声斯特林发动机热动力学特性的CFD研究——第一部分:热声自激振荡演化过程 总被引:2,自引:1,他引:2
采用商业计算流体动力学(CFD)软件Fluent6.0对热声斯特林发动机热动力学特性进行了热声自激振荡演化过程的数值模拟研究.主要研究了边界条件、初始条件和数值离散方法对模拟瞬态、可压缩、非线性的热声系统的重要影响,同时给出了两种在回热器内部建立温度梯度的方法,比较了它们对应的不同自激振荡演化过程.模拟结果表明,在高于功产生的临界温度梯度时,波动压力振幅被显著放大.本研究初步验证了该CFD研究的有效性. 相似文献
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大型多功能热声发动机的研制及初步实验 第二部分:热声发动机的初步实验 总被引:13,自引:5,他引:13
行波热声发动机在回热器中进行的是可逆热声转换过程,理论上可以更高效地产生和传输声功,因而具有广阔的研究应用前景.对自行研制的大型多功能热声发动机进行了初步实验,着重研究了系统的起振、消振过程及压力波动情况.实验结果表明,该热声发动机比纯驻波型热声发动机具有更低的起振温度、更大的压比及更高的热声转换效率.以氮气为工质,在充气压力为9×105 Pa的条件下,该热声发动机最大压比达1.21,工作频率为25 Hz,这是当前国际上处于前列的实验结果. 相似文献
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A resonance tube is an important component of a thermoacoustic engine, which has great influence on the performance of the thermoacoustically driven pulse tube refrigerator. A standing wave thermoacoustic engine is simulated with linear thermoacoustics. Computed results show that an appropriate accretion of the resonance tube length may lead to a decrease of the working frequency and an increase of the pressure amplitude, which will improve the match between the thermoacoustic engine and the pulse tube refrigerator. The theoretical prediction is verified by experiments. A refrigeration temperature as low as 88.6 K has been achieved with an optimized length of the resonance tube, helium as working gas, and 2200 W of heating power. 相似文献
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《低温学》2017
Periodic and spontaneous on-off oscillation belongs to the onset and damping behaviors of thermoacoustic engines, and investigations on this phenomenon lead to better operation of the thermoacoustic engines with stable performances. In this paper, the quasi- periodic on-off oscillation in a small-scale traveling wave thermoacoustic heat engine with a resonator length of only 1 m was experimentally investigated. The type of working media, mean pressure and the input heating power are the main operating parameters, which significantly affect the formation of the periodic on-off oscillation. The experimental results demonstrated there was a critical charge pressure over which the periodic on-off oscillation could happen. For the small- scale engine with helium gas as the working media, the mean pressure threshold value was about 1.4 MPa and the on-off oscillation occurred with a single frequency. Using nitrogen and argon gas as the working media, the on-off oscillation was not observed. The reason was qualitatively analyzed as well. 相似文献
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Experimental investigation on a thermoacoustic engine having a looped tube and resonator 总被引:1,自引:0,他引:1
The purpose of this paper is to study the impact of regenerator hydraulic radius, resonator length, and mean pressure on the characteristics of the tested thermoacoustic engine, which has a looped tube and resonator. Two different acoustic oscillations are observed in the tested engine [Yu ZB, Li Q, Chen X, Guo FZ, Xie XJ, Wu JH. Investigation on the oscillation modes in a thermoacoustic stirling prime mover: mode stability and mode transition. Cryogenics 2003;43(12):687-91]. In this paper, they are called two acoustic modes, high frequency mode (with a frequency independent of the resonator length) and low frequency mode (with a frequency depending on the resonator length). Experimental results indicate that the relative penetration depth (the ratio of penetration depth over hydraulic radius) plays an important role in the excitation and pressure amplitude of the two acoustic modes. For each tested regenerator hydraulic radius, there is a measured optimal relative penetration depth, which leads to the lowest onset temperature difference. Note that, in the tested engine, the measured optimal relative viscous penetration depths are in the range 3-5 (for low frequency mode). Furthermore, experimental results also show that the resonator length affects the presence of high frequency mode in this engine. 相似文献
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The performance of a small thermoacoustic Stirling heat engine (TASHE) was investigated with three kinds of working gases experimentally and numerically. The examined performances focused on the operating frequency, onset temperature, pressure amplitude and some temperature characteristics after onset. The working frequency with nitrogen, argon and helium as the working gas was 45 Hz, 42 Hz and 130 Hz, respectively. The engine worked with helium in a much wider range of mean pressure than with nitrogen and argon. There was an optimal mean pressure for the minimum onset temperature for each working media. Using nitrogen and argon as working gas rather than helium, another optimal mean pressure for the highest pressure ratio was obtained in the experiment. The loop dimension was indispensable in determining the frequency and the highest pressure ratio was observed in the resonator cavity. 相似文献
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《低温学》2015
A 300 Hz pulse tube cryocooler (PTC) driven by a three-stage traveling-wave thermoacoustic heat engine (TSTHE) has been proposed and studied in this paper. In the configuration, three identical thermoacoustic heat engine units are evenly incorporated in a closed traveling-wave loop, in which three pulse tube cryocoolers are connected to the branch of each thermoacoustic heat engine. Compared with the conventional thermoacoustic heat engine which involves a traveling-wave loop and a long resonator, it has advantages of compact size and potentially high thermal efficiency. A TSTHE–PTC system was designed, optimized and studied in detail based on the thermoacoustic theory. Firstly, numerical simulation was conducted to design the system thus the optimum structure parameters of the system were obtained. With the operating condition of 4 MPa mean pressure and high working frequency, a cooling power of 7.75 W at 77 K and an overall relative Carnot efficiency of 11.78% were achieved. In order to better understand the energy conversion characteristics of the system, distributions of key parameters such as acoustic work, phase difference, dynamic pressure, volume flow rate and exergy loss were presented and discussed. Then, the coupling mechanism of the system was investigated. In addition, influence of coupling position on the system performance was further studied. 相似文献
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Obtainable lowest temperature of a thermoacoustically-driven pulse tube cooler is generally limited by the pressure ratio provided by the thermoacoustic engine with helium as working gas. It is also known that a thermoacoustic engine filled with nitrogen can generally provide much larger pressure ratio and lower frequency than the same engine filled with helium. Here we introduce an innovative system configuration which uses an elastic membrane as the interface between the thermoacoustic engine subsystem and the pulse tube cooler subsystem. The membrane can transport acoustic work from the engine to the cooler, and meanwhile separate the working gases used in respective subsystems. Through this way, it is possible for the engine to operate with nitrogen to provide larger pressure ratio and more suitable frequency for the pulse tube cooler which can still use helium as the working gas. To test this idea, a thermoacoustically-driven pulse tube cooler was built. With the innovative configuration, the pulse tube cooler reached a lowest temperature of 139 K. On the other hand, without the membrane, the PTC only achieved a lowest temperature of 186 K when using nitrogen and 145 K with helium for both the PTC and the engine. 相似文献