共查询到19条相似文献,搜索用时 109 毫秒
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分析了叉车液压传动系统中气泡形成的原因、产生的机理以及气泡在液压系统中存在的主要方式和形成的主要途径。从影响系统正常工作,导致气穴气蚀的发生,油温升高致油液变质以及产生噪声和振动等几个方面论述气泡对液压系统的危害,并提出了一些减少气泡的方法。在设计液压系统时注意尽量减少气泡的产生,减少危害。 相似文献
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通过高速摄像和压力分布测量等方法从实验和仿真两方面对节流槽内高速流动中的气穴现象进行了研究,并建立了槽内流动模型。研究发现,节流槽内由于高速流动和流体脱离而产生的低压区是造成气泡流产生的根本原因,压力分布对气穴与噪声特性有直接的影响,节流槽结构通过压力分布决定了气泡的尺度大小和成长过程。该研究对于建立基于流场仿真预测阀口气穴的方法,以及对液压元件的噪声控制具有重要价值。 相似文献
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液压系统的噪声是一种十分有害的恶性干扰,如不加以控制,将会产生恶性循环,导致系统发生故障。噪声的产生不外乎是由于系统的液压与机械振动、脉冲、气穴、油液污染及其液压元件的磨损等等。对于噪 相似文献
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气泡滞留会严重地损害微型压电泵的输出性能,因此减少气泡滞留将有效地提高压电泵系统的稳定性和可靠性。泵腔作为气泡滞留的主要区域,同时是决定输出性能的重要元素,所以改变腔高将对气泡滞留产生重要的影响。本文从气泡压力降和输出压力两个方面建立数学模型,以此分析腔高对气泡滞留的影响规律,最后通过气泡滞留实验进行验证。实验结果表明,腔高为0.15mm时,压电泵具有优良的输出性能和排气泡能力,在进入120个0.02mL气泡后,压电泵仍具有稳定的输出压力(8.1kPa)和输出流量(4.2mL/min);腔高为0.05mm和0.20mm时,压电泵在进入一个气泡后即丧失了工作能力,排气泡能力差,而腔高为0mm和0.10mm时,压电泵分别进入47和70个气泡后丧失了工作能力。实验表明选取合理的腔高可以有效地减少气泡的滞留。 相似文献
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<正>装载机工作时,产生不正常响声的原因主要来自3方面。一是气穴。液压系统的工作油液含有空气或液压系统密封不良,在工作时吸入空气,在低压时空气游离出来形成气泡。气泡随油液流到高压区,在高压的作用下,气泡被击破溶解于油液中,产生局部液压冲击,局部压力和温度发生突变(高压区域温度可高达1000℃,压力可高达150~200 MPa),使系统产生很高的噪声和强烈的振动。 相似文献
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为研究双自由度(2D)伺服阀先导控制阀口处气穴现象的影响因素及对阀芯稳定性的影响,运用Fluent软件中cavitation模型对2D伺服阀矩形先导阀口进行了气穴特性的仿真研究。研究表明,在出口压力低于1 MPa时,阀口处会出现气穴现象,且因气穴指数σ较小,故在弓形感受通道会出现气泡现象,出口压力高于5 MPa时,无明显气泡现象但阀口处的气穴仍然存在;随着入口流速增加,阀口内侧壁和外侧壁处气穴强度和分布范围增加;在出口压力0.1 MPa情况下,随着阀口开度增加气穴现象减弱。结果表明,2D伺服阀正常工作时先导阀口处会产生气穴,对伺服阀阀芯运动的稳定性产生干扰。 相似文献
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一台QY52型汽车起重机工作中发出噪声,检查分析如下:
(1)液压泵噪声
①当油液中混入空气后,易在泵的高压区形成气穴,并以压力波的形式传播,造成油液振荡,导致系统产生气蚀噪声。 相似文献
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Zhang Jian-hui Xia Qi-xiao Bai Heng-jun Ning Hong-gang Onuki Akiyoshi 《Frontiers of Mechanical Engineering in China》2006,1(4):429-433
The volume valve piezoelectric pump has received increasing attention from many areas because of its different characteristics
such as the absence of chemical pollution and electromagnetic pollution. However, when the pump is working, it produces cavitations
and the air bubbles that originate from these will flow out of the pump. Cavitations occurring in the pump will bring out
noise and shorten the life of the pump. Furthermore, air bubbles flowing out of the pump will hinder its application in areas
such as medical treatment and health care where blood transfusion and infusion are concerned. As a solution to this disadvantage,
the CR3DMS (cavitations resistance with 3-dimensional mesh structure) method is developed, which is tested and verified to
be effective on not only reducing the occurrence of cavitations and eliminating cavitations’ flowing out, but also restraining
the emission of noise. In conclusion, the pump with CR3DMS, on the relationship between flow and driving frequency and the
relationship between flow and the number of Resistant-Layers in both theory and test, are analyzed.
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Translated from Chinese Journal of Mechanical Engineering, 2006, 42(5) (in Chinese) 相似文献
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应用动网格和气穴模型,对某外啮合齿轮泵进行三维数值模拟研究,分析齿轮泵的总体性能和内部流场特性,得出齿轮泵流量随进口压力减小的变化规律,模拟其内部气穴的产生、运输以及破灭过程。计算结果表明,在齿轮泵的工作过程中啮合处会产生气穴。若泵进口腔的压力较高,气穴就会随着工作液的填充而迅速消失,齿谷输送的工作液中不会包含气穴,齿轮泵的流量只会随进口压力的降低略微下降;若泵进口腔的压力过低,气穴不但难以消失,而且还会被齿谷输送走,导致齿轮泵质量流量迅速下降。齿轮泵进口压力越低,则输送的工作液中气体所占的比体积越高,质量流量下降越明显。 相似文献
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为了分析某型号轴流泵叶轮汽蚀状态下汽液两相流特征,本文基于均相流模型、RNG k-ε湍流模型与SIM-PLEC算法,分别从外特性和内部流场两方面分析了轴流泵叶轮的空化过程,通过定量分析不同NPSH下轴流泵的扬程下降和空泡分布的对应关系,讨论了不同空化状态下叶轮内部速度场和压力场的分布,寻找出轴流泵空化发生破坏的位置和发展趋势。数值模拟结果表明,空化初生时空泡产生于叶片背面进口轮缘处,随着轴流泵进口压力的不断降低,叶片背面外缘处空泡逐渐向轮毂侧发展,且外缘侧空泡不断向前推进,在装置汽蚀余量NPSH为6.62m时,空泡基本覆盖叶片的背面,此时叶片丧失了部分做功能力,且扬程下降明显。计算模型泵进行了现场运行试验,试验结果表明,数值模拟的空泡分布与实际破坏位置一致,验证了数值计算的准确性,也为解决轴流泵汽蚀破坏问题提供了内流流场参考。 相似文献
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Experimental investigation on the flow-induced noise under variable conditions for centrifugal pumps 总被引:1,自引:0,他引:1
With extensively using of centrifugal pumps,noise generation in these pumps is increasingly receiving research attention in recent years.The noise sources in centrifugal pumps are mainly composed of mechanical noise and flow-induced noise.And the study of flow-induced noise has become a hotspot and important domain in the field.The flow-induced noise closely related to the inner pressure pulses and vibration of volute in pumps,therefore,it is necessary to research the interaction and mechanism among them.To investigate the relationships,a test system is designed which includes a test loop and a measurement system.The hydrophones and pressure sensors are installed on the outlet of the pump and vibration acceleration sensors are disposed on the pump body.Via these instruments,the signals of noise,pressure pulses and vibration are collected and analyzed.The results show that the level of flow-induced noise becomes smaller as the flow increment during low flow rate operations,and it is steadily close to the design point,then it increases with the growing of flow rate in high flow rate conditions.Furthermore,there are some similar peak points in the power spectrum charts of noise,pressure pulses and vibration.The broadband noise at low flow rate is mostly focused on the region of 0-40 times shaft frequency,which is mostly made by rotating stall and vortex;while the noise at high flow rate conditions is focused on the region of 60-100 times shaft frequency,which may be mostly made by cavitations.The proposed research is of practical and academic significance to the study of noise reduction for centrifugal pumps. 相似文献
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A numerical simulation on suction vortices behavior in a centrifugal pump was carried out to investigate their influence on
the internal flow through impellers including formation and shedding of cavitation by using a finite-volume method and k-ω
Shear Stress Transport turbulence model. For cavitating flow, a two phase homogeneous cavitation model was used. A full three-dimensional
flow in a single-section centrifugal pump consisting of a six blade impeller and shroud ring was computed with structured
mesh. A constant suction vortex is imposed as a boundary condition. Vortices behavior was investigated according to the variation
of flow rates of two pump systems with and without suction vortices. From the results, suction vortices induced biased flow
structure and more cavitations, especially at the low flow rate condition. Complicated internal flow phenomena through impellers
such as formation of cavitations, growing and shedding of the vortex, flow separation and flow unsteadiness due to the suction
vortices are investigated and discussed. 相似文献
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风冷热泵机组是中央空调的冷热源,但其噪声给周围环境带来严重污染,成为一个噪声源.如何治理噪声将是一个大问题,笔者通过工程实例,对如何有效、经济地治理风冷式热泵机组的噪声进行了探讨. 相似文献
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