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旋转离心叶轮与叶片扩压器间耦合流动的数值分析 总被引:3,自引:1,他引:2
以离心压气机内部动静部件耦合的非定常流场为研究对象,本文提出了动静耦合统一正命题型式,采用κ-ε紊流模型、同步计算动静耦合流场的方法,分别对下同流量工况下离心叶轮与叶片扩压器内部非定常流动进行了数值计算。计算结果与激光多普勒测量结果进行了比较:在设计工况下,离心叶轮与叶片扩压器相互匹配较好,而在非设计工况下,流道内流动趋向恶化。说明计算结果是有一定的可信度;计算结果同时说明,只有采用非定常算法,才有可能较好地描述动静部件耦合的流场。 相似文献
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使用确定应力模型研究离心压气机叶片相互作用 总被引:3,自引:0,他引:3
离心压气机叶轮和扩压器叶片间空隙很小,在无叶区和半有叶区的流动非定常特性十分明显。特别是离心叶轮出口通常的射流/尾迹流动使得有叶扩压器进口在时间、空间两个尺度上都存在十分强烈的不均匀性。叶轮和扩压器叶片间的相互作用,历来都被认为是影响离心压气机效率和稳定工作范围的重要因素。本文引入确定应力模型和改进的计算域延伸方法,计算了Krain离心压气机组的流场,着重分析了叶轮出口无叶区、半无叶区等叶片间相互作用最强烈的区域的复杂流动现象。 相似文献
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基于非线性谐波法的离心压气机确定应力场分析 总被引:1,自引:0,他引:1
本文采用非线性谐波法与定常计算方法,对离心压气机的内部流场进行了数值模拟,对比了时均流场与定常流场的差别,研究了离心压气机确定应力分布的特点。结果表明,采用非线性谐波方法所得到的压气机内部流场宏观结构与定常结果基本一致,但流场参数分布细节存在较明显差别,且这种差别与对应的确定应力场的分布特征吻合,验证了确定应力是引起时均流场与定常流场差别的原因。对确定应力的分布特征分析表明,离心压气机内确定应力在流向上呈现为从叶轮出口向上下游逐渐递减的趋势,在叶高方向上表现为从叶根到叶顶逐渐递增趋势;且在整体上,确定应力的空间不均匀特性在叶轮出口处最为强烈,表明离心压气机内部最强非定常效应同样位于叶轮出口。 相似文献
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本文使用S_1/S_2全三元送代计算和三元N-S方程解两种方法对含有分流叶片的Eckard离心叶轮内部三元流场进行了数值分析,并与激光测量值进行了比较。侧重分析了叶轮内部分离流动和射流尾迹区的形成和特点。 相似文献
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一个跨音风扇级转/静干扰流动的时间精确模拟 总被引:5,自引:1,他引:4
本文采用双时间步法,较为方便地将孤立叶排定常流场求解拓广为转/静干扰非定常流场时间精确求解,而且该流场时间精确求解方法收敛速度较作者最初工作有较大提高.文章通过对一跨音风扇级非定常流场时间精确模拟,对叶轮机非定常流动建立了一定理解. 相似文献
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多级离心泵内叶轮出口压力脉动研究 总被引:3,自引:0,他引:3
为研究瞬态工况下离心泵叶轮出口处的压力脉动情况,为离心泵泄漏流道流动提供边界条件,建立了包含叶轮和导叶流道的离心泵模型,基于CFD方法计算得到了其在不同工况下的性能参数,利用测试数据对结果进行了验证。分析了瞬态工况下叶轮出口处压力的变化趋势,比较了不同工况对叶轮出口压力脉动的影响,发现叶轮出口压力随叶轮旋转呈周期性变化,压力脉动频率与转速及叶轮数量有关;偏工况时叶轮出口压力脉动趋势与额定工况基本一致,但脉动频率及脉动幅值有较大区别;随离心泵转速增加,叶轮出口处压力脉动的最大值和最小值均呈减小趋势,但幅值随转速增加而增加,且增幅明显。 相似文献
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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
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Unsteady wake from upstream components of landing gear impinging on downstream components could be a strong noise source.The use of a plane jet is proposed to reduce this flow-induced noise.Tandem rods with different gap widths were utilized as the test body.Both acoustic and aerodynamic tests were conducted in order to validate this technique.Acoustic test results proved that overall noise emission from tandem rods could be lowered and tonal noise could be removed with use of the plane jet.However,when the plane jet was turned on,in some frequency range it could be the subsequent main contributor instead of tandem rods to total noise emission whilst in some frequency range rods could still be the main contributor.Moreover,aerodynamic tests fundamentally studied explanations for the noise reduction.Specifically,not only impinging speed to rods but speed and turbulence level to the top edge of the rear rod could be diminished by the upstream plane jet.Consequently,the vortex shedding induced by the rear rod was reduced,which was confirmed by the speed,Reynolds stress as well as the velocity fluctuation spectral measured in its wake.This study confirmed the potential use of a plane jet towards landing gear noise reduction. 相似文献
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Viscous dissipation and its contribution to turbulent kinetic energy (TKE) budget are investigated in the asymmetric jet–wake flow of a forward-curved centrifugal turbomachine. Single-plane three-dimensional turbulent data are obtained using stereoscopic particle image velocimetry (SPIV). Viscous dissipation is indirectly estimated from subgrid-scale (SGS) dissipation (SGS energy flux) by filtering velocity field using a top-hat filter. The filter scale should be within the inertial sub-range and this is ensured by spectral analysis of the measured field. Reduction of turbulent energy flux for smaller filter scales plus underestimation of viscous dissipation as compared with other TKE terms both suggest the presence of spectral shortcut. This bypass energy transfer (from intermediate scales towards dissipative scales) works in parallel with direct SGS energy transfer and affects the classical energy cascade. Analysis of TKE budget in the rotor exit region shows significant radial/circumferential variations in the contributing terms. These variations are mainly due to jet–wake–volute interactions, circumferential asymmetry of volute area and expansion of flow toward the fan outlet. 相似文献
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Laser velocimetries, such as LDV or laser-2-focus (L2F) velocimetry, have been widely used for a flow measurement in a high-speed rotating impeller. A particle image velocimetry (PIV) is one of the popular velocity measurement techniques for the ability to measure a velocity field. And a PIV offers an extensive velocity field in an extremely shorter measurement time than the laser velocimetries. In the present experiment, a PIV was applied to a flow measurement in a transonic centrifugal impeller. A phase locked measurement technique every 20% blade pitch was performed to obtain a velocity field over one blade pitch of the inducer. The measured velocity field at the inducer of impeller clearly showed a shock wave generated on the suction surface of a blade. The validity of the present technique was also discussed. 相似文献