共查询到20条相似文献,搜索用时 509 毫秒
1.
《工程热物理学报》2017,(9)
离心泵内部由叶轮-隔舌动静干涉作用诱发的压力脉动是激励离心泵振动噪声的重要因素,对泵的稳定、安全运行有重要影响。为了全面获得离心泵压力脉动特性,本文采用试验手段对一台低比转速离心泵进行压力脉动试验,在蜗壳周向均布20个高频压力脉动传感器对压力信号进行提取。结果表明:离心泵压力频谱呈现典型的离散特征,峰值信号出现在叶频及其高次谐波处,压力频谱中没有出现明显的轴频及其和叶频非线性干涉诱发的峰值信号。不同测量点处压力脉动幅值差异显著,在设计点及大流量工况,叶频处压力脉动幅值极大值点出现在隔舌后端区域范围内,而在隔舌前部区域内,压力脉动幅值较小;且随着角度的增加,叶频处压力脉动幅值呈现递减的趋势,而在小流量工况叶频处压力脉动幅值并没有出现在隔舌后端区域内。流量对叶频处压力脉动幅值影响显著,压力脉动幅值极小值点出现在0.9Q_d附近,而偏离该工况时,压力脉动幅值迅速上升。 相似文献
2.
3.
《工程热物理学报》2020,(7)
为研究离心泵导叶流道进口处压力脉动的分布及传播规律,深入探究导叶式离心泵内动静干涉作用机理。试验采集某核级离心泵相邻两个导叶流道进口处压力脉动信号,并对其进行分析。结果表明:模态节径模式分析方法可以用来分析预测压力脉动主要特征频率成分,导叶流道进口处压力脉动主要为叶片通过频率及其倍频,并以此形式沿叶轮旋转方向向下传播。相同导叶流道进口处流体流动具有不均匀性,各测点压力脉动主要特征频率及最大幅值对应频率不同。压力脉动在叶片通过频率及其倍频处相关性强,随着流量增大至设计工况,压力脉动能量逐渐集中到叶片通过频率及其倍频处。研究可为降低泵内压力脉动提供一定参考。 相似文献
4.
《工程热物理学报》2015,(12)
以单级蜗壳式离心泵为研究对象,基于RANS进行了全流场的非定常数值计算,探讨了叶轮的非定常流动特征,重点分析了叶轮出口沿轴向变化的圆周面流域内各节点的压力分布特性。结果表明:在叶片压力面及叶片后缘尾迹区发生了剧烈的湍流脉动现象;不同工况下叶轮出口圆周方向的压力系数C_p均在隔舌附近产生极值;额定工况Q/Q_N=1时,叶轮出口圆周方向的压力系数C_p呈稳定周期性分布,随着工况的改变,压力系数C_p沿蜗壳周向分布不均匀性增加;小流量工况下叶轮流域内发生了明显的流动分离现象,流道内产生了较大尺度的分离涡,破坏了叶轮出口圆周方向压力系数C_p的周期性分布特性;叶轮出口圆周压力系数C_p沿中截面两侧的流域内几乎对称分布;在Q/Q_N=0.2小流量工况下,压力脉动频谱图低频段内出现了较多复杂的激励信号,认为这与流域内的分离涡结构具有一定关联。 相似文献
5.
6.
《工程热物理学报》2010,(11)
基于N-S方程和标准κ-ε模型对出口等速度环量的轴流式模型泵在不同工况下进行了全流道数值模拟,给出了叶片表面相对速度和压力的分布规律,并将叶轮出口处速度分量计算结果和球形五孔探针测量结果进行比较。分析结果表明:叶片表面的相对速度沿径向逐渐增大,流动分布规律符合圆柱层无关性假设;叶片发生汽蚀的危险区域约位于吸力面外缘进口边到出口边的1/4位置;最优工况下叶轮出口处流场呈螺旋形向外运动趋势,出口旋转动能占出口总动能的34%左右;速度环量测量值从轮毂至轮缘逐渐减小,设计中应适当减小轮毂处圆周分量值,增加轮缘处圆周分量值。研究结果揭示了叶轮表面和出口流动规律,为轴流泵优化设计提供了理论和实际应用参考。 相似文献
7.
《工程热物理学报》2017,(5)
轴流式冷却循环泵是舰船动力系统中的关键设备之一,泵内非稳态流动诱发的压力脉动是影响泵振动水平的主要水力因素。运用特定设计方法对某比转速为471的循环泵进行了设计并通过实验测量进行了性能验证。基于非定常数值计算,获得了不同工况下循环泵多个截面上压力脉动系数的变化规律。研究表明:叶轮进口压力脉动系数沿径向呈递增趋势,轮缘处流体激励能量最大且主要集中于叶频;叶轮出口压力脉动系数在轮缘和轮毂处取得极大值,主要激励频率为叶频及其高次谐频;导叶出口压力脉动系数沿径向基本一致,主要激励频率为1/5叶频;叶轮出口诱发的叶频压力脉动是决定泵振动水平的主导因素。研究结论为循环泵减振技术的发展提供了一定的理论支撑。 相似文献
8.
9.
离心泵内部非定常流动与流场中生成的旋涡密切相关.本文采用Omega涡识别方法研究离心泵流场涡结构及非定常流动特性,阈值选择为0.51.分析得出LES湍流模型相对比其他两种湍流模型涡识别结果更为细致,对叶片流道中的小涡结构可以很好地捕捉.设计工况下,LES模型识别出的涡面积数值是DDES模型的1.15倍,是SSTk-ω模型的1.55倍.压力脉动受流场空间位置与工况影响较大,其主要激励为叶频,并且压力脉动强度与涡面积密切相关.叶轮出口处的涡结构周期性脱落,在隔舌处会撞击隔舌而破裂.离心泵动静干涉的产生与叶轮出口处的涡结构脱落有关. 相似文献
10.
为了减小离心泵的压力脉动,本文提出了一种新型分半错列叶轮结构,将叶轮分半错列,错列角度分别为10°、20°与30°,以比转速为69的离心泵为研究对象,对原模型、叶轮分半错列10°、20°与30°模型进行不同工况下数值计算,获得了泵水力性能与内部压力脉动特性。通过对比分析发现:相比与原始模型,采用分半错列叶轮能有效提高离心泵水力性能;当叶轮分半错列30°时,泵性能提升最大,叶轮与蜗壳间动静干涉作用大幅下降,泵内压力脉动能量降低。研究表明,分半错列离心叶轮是低噪声泵设计可采用有效途径之一。 相似文献
11.
12.
13.
叶片尾缘掠型对离心压气机特性影响研究 总被引:1,自引:0,他引:1
针对叶片尾缘掠型对离心压气机特性影响开展了数值仿真与试验验证的研究工作,详细分析了尾缘掠型对压气机特性的影响规律和压气机叶轮内部流动特征,研究结果表明:尾缘掠型能够提升压气机出口的总压,使离心压气机压比变高,自由掠叶型相比于斜掠叶型,压比会进一步提升。叶片尾缘掠型能够有效抑制尾缘流动分离与叶间泄漏效应的结合效果,降低流动分离强度和分离区域,提升叶轮的稳定工作范围与效率。试验验证结果表明采用自由掠型尾缘叶轮,压比随着转速的升高提升幅度变大,最多提升了9.14%,喘振线明显向左偏移,运行流量范围拓宽。尾缘掠型能够有效提升压气机压比和稳定工作范围,是改善压气机特性的有效手段。 相似文献
14.
Experiments on the unsteady flow field and noise generation in a centrifugal pump impeller 总被引:4,自引:0,他引:4
Jong-Soo Choi Dennis K. McLaughlin Donald E. Thompson 《Journal of sound and vibration》2003,263(3):493-514
This paper reports on an experimental investigation of large-scale flowfield instabilities in a pump rotor and the process of noise generation by these instabilities. Measurements of the fluctuating components of velocity and surface pressure were made with hot-wire probes and surface mounted pressure transducers on a seven bladed back swept centrifugal water pump impeller operating with air as the working fluid. The impeller was operated without a volute or scroll diffuser, thereby eliminating any sound generation from pressure fluctuations on the volute cutoff. Thus the study focused on flow field and noise components other than the blade passage frequency (and its harmonics). The primary goal of the study was to provide fundamental information on the unsteady flow processes, particularly those associated with the noise generation in the device. It was further anticipated that detailed flow measurements would be useful for the validation of future computational simulations.The measured data at the discharge show a jet-wake type of flow pattern which results in a strong vorticity field. The flow with high velocity found on the pressure side of the impeller tends to move to the low-pressure region present at the suction side of the passage as a form of roll-up around the blade trailing edge. This motion causes an unsteady flow separation at the suction side of the blade and consequently disturbs the flow in the adjacent passage. By interacting with the impeller blades near the trailing edges, this instability flow causes a periodic pressure fluctuation on the blade surface and generates noise by a trailing edge generation mechanism. The spectrum of surface pressure measured at the trailing edge of each blade reveals a cluster of peaks which were identified with azimuthal mode numbers. The correlation between the acoustic farfield pressure and the surface pressure on the impeller blade has proven that the azimuthal modes synchronized with the number of impeller blades generate noise much more efficiently than the other modes. The paper also clarifies the correlation between unsteady flowfield measurements, in both impeller and laboratory co-ordinates, with the radiated noise properties. Thus some light is shed on the noise generation mechanisms of this particular device. 相似文献
15.
Transient behavior of a centrifugal pump during starting period 总被引:1,自引:0,他引:1
A theoretical analysis on transient flow inside a centrifugal pump was carried out, building on unsteady and incompressible fluid equations applied to the impeller during the starting periods. The transient flow behavior is governed by two hyperbolic partial differential equations; namely continuity and motion equations. The characteristics method of the specified time intervals was used to analyze the dynamic characteristic of the pump. To follow the dynamic behavior of the pump during startup periods, a numerical study was performed on the pump impeller with different openings of the discharge valve. The comparison between the numerical and experimental results of the pump characteristic curve has shown a good concordance. The results have also revealed that the pressure increase is important in the case of a short starting period of the pump and a large mass of water in the pipelines. In this study, the effect of the impeller diameter and number of blades on the pressure evolution was also analyzed. 相似文献
16.
离心压气机叶片扩压器气动优化设计 总被引:3,自引:0,他引:3
本文以某高速离心压气机叶片扩压器为研究对象,采用Kriging模型在设计工况下对其进行气动优化设计,以获取较高的"叶轮 扩压器"等熵效率,同时保证扩压器出口静压不降.Kriging模型大大加速了设计过程,得到的优化结果和原始设计相比,在性能上有了较大改善. 相似文献
17.
Unsteady flow visualization at part-load conditions of a radial diffuser pump: by PIV and CFD 总被引:3,自引:0,他引:3
The present study provides flow visualization on complex internal flows in a radial diffuser pump under part-load conditions
by using the three-dimensional Navier-Stokes code CFX-10 with Detached Eddy Simulation (DES) turbulence model. Particle Image
Velocimetry (PIV) measurements have been conducted to validate numerical results. The CFD results show good agreements with
experimental ones on both the phase-averaged velocity fields and turbulence field. The detailed flow analysis shows that no
separation occurs at 0.75Qdes although a low-velocity zone develops on the rear impeller suction side. Steady flow separations are observed on the impeller
suction sides at 0.5Qdes but with different onsets and amounts. When reducing the flow rate to 0.25Qdes, CFD predicts different types of back flows in the impeller region, including steady leading edge separations, rotating vortex
in the impeller wake region, and back flow on the impeller pressure side. 相似文献
18.
针对抛光粉沉降特性数值计算这一超大规模非线性问题,基于Kahan线性化解决了超大规模流固耦合计算问题。研究了以羟基铁粉和硅油为主要成分组合而成的抛光粉多相流在梯度磁场下抛光区域的沉降特性。以质量分数70%、粒径5 μm的羟基铁粉和粘度为0.973 Pa·s的硅油组合而成的抛光粉为研究对象,实现了不同的抛光轮转速、不同嵌入深度以及不同羰基铁粉质量分数情况下的沉降规律分析。结果发现:磁流变抛光区域的抛光粉会随着抛光轮转速的增大而增多;当到达出口时,抛光粉的分布趋于稳定状态;抛光粉会随着嵌入深度的增加而增多并存在饱和区;羟基铁粉的质量分数以非线性的方式影响沉降能力。 相似文献
19.
A simple acoustic model to characterize the internal low frequency sound field in centrifugal pumps 总被引:2,自引:0,他引:2
Conventional centrifugal pumps with volute casing generate fluid-dynamic noise particularly at the so-called blade-passing frequency, which is attributed to the interaction of the flow exiting the pump impeller with the volute tongue. Following previous work by the authors to characterize the effect of that blade–tongue interaction on the tonal sound produced, this paper presents a simple acoustic model for centrifugal pumps that considers ideal sound sources of arbitrary position and properties. The model is to be implemented in a software code that applies it systematically to a pump previously tested at laboratory, until identifying the set of ideal sources that best reproduce the pressure fluctuation measurements. In this model, the ideal sources are assumed to radiate plane sound waves along the impeller channels, volute, and outlet diffuser. The volute was considered to be composed by a succession of slices, each of them equivalent to a linear 3-port acoustic system with individual sound transmission and reflection coefficients. A series of tests was conducted to check the validity of the acoustic model, by applying an external acoustic load onto the pump outlet duct and measuring the noise reflected. The resulting reflection coefficient was in good agreement with the predictions of the acoustic model. Finally, the model was used to investigate the pump internal sound field at the blade-passing frequency when operating at 70% of nominal flow rate. It was concluded that the sound field can be characterized reasonably by a dipole-like source located at the tongue region. 相似文献
20.
Takuma Sato Fabian Chacon Logan White Venkat Raman Mirko Gamba 《Proceedings of the Combustion Institute》2021,38(3):3769-3776
High-fidelity simulations of an experimental rotating detonation engine with an axial air inlet were conducted. The system operated with hydrogen as fuel at globally stoichiometric conditions. Instantaneous data showed that the detonation front is highly corrugated, and is considerably weaker than an ideal Chapman–Jouguet wave. Regions of deflagration are present ahead of the wave, caused by mixing with product gases from the previous cycle, as well as the injector recovery process. It is found that as the post-detonation high pressure flow expands, the injectors recover unsteadily, leading to a transient mixing process ahead of the next cycle. The resulting flow structure not only promotes mixing between product and reactant gases, but also increases likelihood of autoignition. These results show that the detonation process is very sensitive to injector design and the transient behavior during the detonation cycle. Phase-averaged statistics and conditionally averaged data are used to understand the overall reaction structure. Comparisons with available experimental data on this configuration show remarkable good agreement of the predicted reacting flow structure. 相似文献