共查询到18条相似文献,搜索用时 222 毫秒
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用实验方法研究了一端固定、一端铰支输流管道在脉动内流作用下的参数共振问题。对实验管道在几种不同的平均流速下做了多次重复实验,获得了第一振型1/2次谐波参数共振相关实验数据。实验结果表明:当平均流速达到一定值时,一端固定、一端铰支管道在一定的脉动流振幅和脉动频率下会产生第一振型1/2次谐波参数共振;脉动流振幅越大,发生参数共振的频率范围也越大,当脉动流振幅小于一定值时,不再发生参数共振;平均流速越大,发生参数共振所需要的脉动流频率就越小,即低频脉动时平均流速越大管道越容易失稳。实验结果与理论分析结果是一致的。对可能引起定量误差的原因进行了较详细的分析。 相似文献
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利用试验的方法研究两端固定输流管道在脉动内流作用时的参数共振特性,建立了一套输流管道试验系统,可以在定常流、脉动流和支承运动等情况下对悬臂、两端固定和两端铰支等多种边界条件的管道进行振动试验,同时给出了一些重要参数的有效测量方法。在对两端固定管道的试验中,重点观察和分析了第1振型1/2次谐波参数共振,并用试验的方法确定了相应的参数共振区域。将其与理论共振区域进行对比,二者在定性上得到了较好的吻合。 相似文献
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针对TBM掘进过程中液压管道在强振动环境下发生共振,导致管道振动加剧的问题,建立了基础振动下两端固支输流管道流固耦合数学模型,运用Galerkin方法和Matlab工具对其进行了求解,且对其结果进行了实验验证,得到了管道发生共振的临界固支间距,并分析了基础振动和结构参数对临界固支间距的影响,进而制定了避免管道发生共振的结构设计流程。结果表明:管道发生共振的临界固支间距随基础振动频率的增大而减小;管道内径每增加5 mm,临界固支间距的上界增大0.26 m;管道厚度为3 mm时,厚度每增加1 mm,上界增大2.87%。 相似文献
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消防水炮自适应炮头可根据流体压力和流量变化自动调整炮口开度,从而显著提升其射流性能。考虑自适应炮头射流系统中流体的压力脉动,结合流体体积弹性模量与刚度间的关系,建立基于时变流体刚度的射流系统参数振动动力学模型,采用多尺度法推导脉动激励频率接近射流系统固有频率和固有频率与脉动频率的组合频率时的共振响应公式,分析射流系统的主共振和组合共振响应。结果表明射流系统发生主共振响应时,激励频率占主导成分,且接近一阶固有频率时系统共振幅值最大;射流系统发生组合共振响应时,激励频率与流体刚度波动频率的组合频率对系统响应的影响与流体脉动频率有关;主共振和组合共振将恶化系统的动力学行为。本项研究可为深入探索自适应炮头射流系统的动力学特性,优化不同工况环境下的设计参数提供理论依据。 相似文献
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纵振换能器与薄圆盘组成的复合系统在实际中有诸多应用。笔者利用有限元法,研究了不同激励面积的纵振换能器激励薄圆盘中心,该激励源频率与圆盘弯曲振动基频相等时,在产生的弯振模式中,激励源面积大小对该圆盘节圆位置的影响。结果表明:激励源面积保持不变时,频率越高的弯振模式,节圆半径越大;对同一纵振激励源面积,振动系统有多个振动模式,纵振激励源面积在一定大小范围内,该振动系统存在一个与纵振换能器频率相近的纵弯共振模式。在纵弯共振模式下,随着激励源面积的增大,节圆半径减小,最终消失,进一步计算发现该节圆的消失与激励源面积和圆盘面积的比值有关。实验与理论计算基本吻合。 相似文献
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输液管道的振动主要是由压力脉动过大引起的。介绍了引起管道振动的压力脉动的计算以及液柱固有频率、共振频率和共振管长的计算,分析了激振力产生的原因。 相似文献
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振动方向角是影响振动机械筛分效率和输送速度等性能的关键参数,为了实现振动方向角的动态调节,针对双轴椭圆振动系统研究了两激振电机供电频率对振动方向角的影响。首先,采用拉格朗日方法建立系统动力学模型,经过理论推导得到两激振电机在不同供电频率下能够实现稳定同步状态,但相比于同供电频率而言,椭圆轨迹的振动方向角发生改变;其次,利用数值方法建立振动系统仿真模型,计算得到系统椭圆轨迹并分析得出振动方向角随供电频率的变化规律;最后,通过搭建双轴椭圆实验样机进行实验验证。研究结果表明:在系统保持同步运转下改变两激振电机的供电频率,振动系统稳定同步状态发生改变且振动方向角能够实现大幅度(0~90°)调节。 相似文献
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主动液压激波作用下管道振动控制的运动分析与试验研究 总被引:3,自引:0,他引:3
为研究在主动液压激波作用下管道振动的动力学特性,建立流体的数学模型,设计出变频液压管网激振测试系统,用特征线法编程对激波作用下的有压脉动内流进行数值模拟。采用有限元法把管道简化为梁模型,建立考虑流固耦合的充液管道在激波作用下的振动方程,在保证特征线各断面与有限元节点重合的前提下,采用Newmark法编程将特征线法求得的流体各断面横向压力载荷施加到管道有限元的单元节点上,求得各断面处的动力响应。仿真结果表明,管道在轴向弹性支撑条件下,在激波作用下管道各断面压力和流速为简谐波,但两者呈反相关系。其横向各断面运动为简谐振动,振幅随系统压力的升高而升高,发现管道横向各断面振动波明显滞后于各断面对应的压力波,而轴向振动则由于弹簧与液体轴向力的耦合作用而出现较高的振动频率。数值模拟结果与试验结果基本比较吻合,揭示出流体动力学参数与管道振动之间的耦合关系,为激波作用下管道的二维振动特性及可控性研究提供了一些理论依据。 相似文献
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All positive displacement pumps produce a pulsating flow. The present paper reports the experimental measurement of steady flow pulsations in the outlet of the internal wheeled pump. In the measured flow, the manufacturing tolerance are responsible of part of the spectra of the whole pulsation. Time-Resolved Particle Image Velocimetry technique has been used for this purpose. The flow pulsation measurement from a direct visualization of the velocity profile was carried out. The flow rate signal is derived from ad-hoc integration algorithm of the radial velocity profile, where the area discretization is a constant parameter that is relevant to minimize PIV errors by velocity gradients regions near the wall. Spectrographic analysis on the experimental data reveled low frequency components related with manufacturing tolerances. Measurements of this non-invasive procedure are compared with detailed CFD numerical results obtained from an improved gerotor model where manufacturing tolerances have been included. To be compared, cross-power spectral density analysis has been applied. The results reported in the paper show a method to provide a fast non-invasive flow pulsation measurement not only for pumps but also could be extended to compare aging effects of other kind of fluid power devices. 相似文献
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Traditional acoustic flowmeters are difficult to use in small-caliber, low-velocity piping systems. In this study, a novel method for fluid velocity measurement in small-diameter pipelines is developed based on the characteristic of acoustic resonance and standing wave tube. This method solves the problem of mutual interference between bidirectional acoustic loops, and realizes the simultaneous measurement of bidirectional resonant frequency. The tiny variation of flow velocity in a small-diameter pipeline can be sensitive by measuring the difference in bidirectional high-order resonance frequency. Experimental results show that the measurement system with a 15 mm diameter pipe has good linearity and high sensitivity to low velocity. Hence, this new method widens the application scope of acoustic flowmeters, especially in small-diameter, low-velocity piping systems. 相似文献
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首次将传动带改进为固支梁模型,研究了传动带由于带速的周期波动而产生的参数振动并确定了振动的稳定域。研究表明当波动周期接近2倍传动带的固有频率时会产生参数主共振,数值模拟结果表明带速和抗弯刚度对传动带的固有频率和共振稳定域均有影响。 相似文献
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Woo Gun Sim B. M. Bae N. W. Mureithi 《Journal of Mechanical Science and Technology》2010,24(10):1981-1988
The characteristics of two-phase flow in a vertical pipe are investigated to provide information for understanding the excitation
mechanisms of flow-induced vibration. An analytical model for two-phase flow in a pipe was developed by Sim et al. (2005),
based on a power law for the distributions of flow parameters across the pipe diameter, such as gas velocity, liquid velocity
and void fraction. An experimental study was undertaken to verify the model. The unsteady momentum flux impinging on a ‘turning
tee’ (or a ‘circular plate’) has been measured at the exit of the pipe, using a force sensor. From the measured data, especially
for slug flow, the predominant frequency and the RMS value of the unsteady momentum flux have been evaluated. It is found
that the analytical method, given by Sim et al. for slug flow, can be used to predict the momentum flux. 相似文献
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K. Doblhoff-Dier K. KudlatyM. Wiesinger M. Gröschl 《Flow Measurement and Instrumentation》2011,22(2):97-103
This article reviews the theoretical background of the measurement of pulsating flow using orifices as flow to pressure transducers, providing a synopsis of work done in this field. Special attention is paid to the temporal inertia and the applicability of expressions thereof given in the literature. Other factors influencing the measurement, such as changing flow profiles and the effect of connection tubes between the pressure sensor and the orifice are discussed. An experiment was performed to investigate the applicability of an equation taking reverse flow and temporal inertia into account for the measurement of pulsating flow with relative pulsation amplitudes around 1 and frequencies up to 50 Hz. It was found that the suggested equation may give tolerable results if the ratio of the pulsating part of the velocity to the angular frequency times orifice diameter is not too high. For high ratios, however, the results could not be explained by the suggested equation. 相似文献