共查询到18条相似文献,搜索用时 125 毫秒
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环路声学共振多级行波热声发动机的机理研究 总被引:1,自引:0,他引:1
针对环路声学共振多级行波热声发动机的工作机理进行了研究,重点分析了环路声学共振4级行波热声发动机无负载工作情况,并比较了环路声学共振4级、8级、16级行波热声发动机的工作性能。计算结果表明,这一行波热声发动机具有较好的声场分布并通过增大回热器横截面积有效降低了回热器内的粘性流动损失。增加环路声学共振多级行波热声发动机的级数仍能获得较为理想的工作性能,并能够增加整机产生净声功率,降低谐振管消耗声功率的比例,相对传统带驻波谐振管的行波热声发动机更为紧凑。 相似文献
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介绍了在Windows2000平台下,三组元液体火箭发动机不稳定燃烧研究试验高频采集系统的实现,给出了系统具体构成,并重点解决了采集板卡的误码率问题,通过试验验证了该系统。 相似文献
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在对扩声系统中声反馈的产生及形成过程进行简要分析的基础上,介绍了抑制声反馈的一般方法,并侧重介绍了反馈抑制器的特点及其在扩声系统中的应用要点。 相似文献
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轧机振动是世界范围内普遍存在的问题。针对某大型连轧机在轧制薄规格带钢时辊系发生严重水平振动现象,设计了一种液压振动抑制器,在辊系轴承座侧面施加振动载荷来抑制辊系的振动,利用MATLAB软件对液压振动抑制器的动态特性进行了仿真研究,结果表明该系统具有良好的辊系振动抑制效果。 相似文献
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提出了内燃机结构辐射噪声的仿真与优化方法,评价了内燃机噪声优化前后车内噪声的变化。建立了内燃机和前围板的有限元模型,通过模态分析验证了模型的精度。采用柔性多体动力学方法计算了内燃机的振动响应,并结合边界元算法得到了结构辐射噪声。完成了机体的结构优化,通过提升刚度使整体模态频率与激励峰值频率分离,从而降低机体结构响应,减小辐射噪声。搭建了内燃机与前围板的声学耦合模型,计算得到经机体结构优化前后的内燃机辐射噪声通过前围板后进入车内的声功率。结果显示,机体的优化方案大幅降低了其辐射噪声,从而减小了整机的辐射噪声。研究内燃机噪声与车内噪声的传递路径后,发现车内噪声有了明显的下降,从而证实了优化设计的可行性和有效性。 相似文献
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本文把声强测量技术应用到内燃机燃烧嗓声与机械噪声分离试验中,推导出燃烧噪声与机械噪声计算公式,提出了一个新的试验方法。 相似文献
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内燃机表面辐射噪声源识别技术初探 总被引:1,自引:0,他引:1
通过测量某内燃机表面振动速度的方法对其进行表面辐射噪声源的识别研究。首先,确定出该内燃机各主要噪声辐射部件,并分别测量其表面振动速度,分析各部件的振动特性,通过表面振动速度计算出各部件辐射的声功率和它们对总噪声的贡献量比值,从而识别出该内燃机的主要表面噪声源。最后提出为改善内燃机整体噪声辐射水平应采取的降噪措施。 相似文献
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Experimental data on acoustic pressure measurements obtained over a wide range of conditions is reported for two simple geometries
that are commonly studied for their combustion dynamics behaviour. These geometries are the confined bluff-body and the confined
backward-facing steps. The data indicate regimes of flow-acoustic lock-on that signifies the onset of combustion instability,
marked by the excitation of high-amplitude discrete tones of sound in the combustor. The highspeed chemiluminescence imaging
of the combustion zone indicates heat-release-rate fluctuations occurring at the same frequencies as observed in the acoustic
spectra. Attention is then devoted to the data obtained under cold-flow conditions to illustrate distinctly different behaviour
than when combustion instability occurs, contrary to the commonly held view that the combustion process does not alter the
underlying fluid mechanical processes under low-Mach number conditions. 相似文献
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Wu X 《Philosophical transactions. Series A, Mathematical, physical, and engineering sciences》2005,363(1830):1247-1259
This paper presents an asymptotic approach to combustion instability in premixed flames under the assumptions of large activation energy and small Mach number. The entire flow consists of four distinct yet fully interactive sub-regions, which accommodate the chemical reaction, heat transport, hydrodynamics and acoustics, respectively. A reduced system was derived to describe the intricate coupling between the flame and acoustics that underlies the combustion instability. The asymptotically reduced system was employed to study the weakly nonlinear interaction between the Darrieus-Landau instability and the longitudinal acoustic mode of the combustion chamber. The general asymptotic formulation includes the influence of enthalpy fluctuation in the oncoming mixture. It is shown that one-dimensional enthalpy fluctuation, through its interaction with flame, produces sound waves, and may cause parametric instability of the flame. The mutual coupling between the sound wave and parametric instability is analysed at the instability thresholds. 相似文献
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