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One-dimensional/three-dimensional analysis of transient cavitating flow in a venturi tube with special emphasis on cavitation excited pressure fluctuation prediction

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Science China(Technological Sciences) 2020年第2期63卷 223-233页

作者： WANG LuYan JI Bin CHENG HuaiYu WANG Jiong long xinping Key Laboratory of Hydraulic Machinery Transients Ministry of EducationWuhan UniversityWuhan 430072China Key Laboratory of Hubei Province for Waterjet Theory and New Technology Wuhan 430072China School of Power and Mechanical Engineering Wuhan UniversityWuhan 430072China State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan 430072China

The large eddy simulation(LES) method is used to simulate cavitating flow in a venturi tube. The simulated results agree fairly well with the experimental data. To quantitatively describe the relationship between cavitation evolution and excited pressure fluctuation in the venturi tube, a modified prediction model is proposed and its accuracy is verified by the LES results. Based on the original one-dimensional model for the external cavitating flow around a hydrofoil, this model is corrected according to the internal cavitating flow characteristics in the venturi tube. The results show that the original one-dimensional model ignores the choking effect of cavitating flow, which is obvious in a venturi tube with a narrow flow channel, thus leading to an inaccurate prediction of pressure fluctuation in the venturi tube. The modified model can significantly overcome its deficiencies and improve the accuracy of the pressure fluctuation prediction, providing a theoretical basis and guidance for engineering application to controlling the pressure fluctuation in a venturi tube or for other internal flows.

关键词： venturi tube LES modified model cavitation pressure fluctuation

Numerical investigation of turbulent flow coherent structures in annular jet pumps using the LES method

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Science China(Technological Sciences) 2018年第1期61卷 86-97页

作者： XU MaoSen YANG Xuelong long xinping LYU Qiao JI Bin Hubei Key Laboratory of Waterjet Theory and New Technology Wuhan University Wuhan 430072 China School of Power and Mechanical Engineering Wuhan University Wuhan 430072 China Research Institute of Nuclear Power Operation Wuhan 430074 China

Annular jet pumps that are used in hydraulic machinery have a very simple structure but very complex internal flow fields. Large eddy simulations were used to study the coherent structures in the turbulent flows in annular jet pumps with various area ratios,m. The distribution, movement and evolution of the coherent structure in the annular jet pumps are described based on vorticity,pressure and Q criteria. All the criteria demonstrate that the vortexes are mainly distributed in the recirculation region and in the mixing and the boundary layers, which have large velocity gradients. The various characteristics of the coherent structures are shown by the different criteria with the vorticity criterion describing the distribution, movement and evolution of the vortexes,the pressure criterion describing the movement and the Q criterion describing the vortex movement and evolution. The vorticity variation in the spanwise direction is larger than the variation in the streamwise direction; however, the streamwise vortex is the main mechanism driving the entrainment of the secondary flow and the mixing. The annular jet pump with m=3.33 had a higher vortex shedding frequency(about 1000 Hz) than that with m=1.72(313–417 Hz). The azimuthal instability is the main reason for the generation of the streamwise vortex from the spanwise vortex. The vortex structures in the recirculation region are very strong,but small and disordered with no periodic vortex rings.

关键词： annular jet pump coherent structure large eddy simulation turbulent flow

VLW equation of state of detonation products

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Science China Chemistry 2009年第5期52卷 605-608页

作者： WU Xiong long xinping HE Bi JIANG XiaoHua Xi’an Modern Chemistry Research Institute Xi’an 710065China China Academy of Engineering Physics Mianyang 621900China Institute of Chemical Materials CAEPMianyang 621900China

Based on the virial theory, we proposed VLW equation of state of detonation products (VLW EOS). Its basic theory and applications were described. The distinct features of the VLW EOS were:First, the detonation performance of the new high energy density materials could be predicted more reliably. Second, it had extensive application. The detonation parameters of both the condensed high energy density materials and the gaseous fuel air explosives could be calculated. Moreover, combustion performance of propellants could also be precisely calculated. The calculation results were satisfactory.

关键词： virial coefficients energetic materials equation of state detonation

Experimental study on landscape of CFRP cutting by abrasive water jet

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排灌机械工程学报 2019年第10期37卷 895-901页

作者： RUAN Xiaofeng ZOU Jialin CHEN Zhengwen XUE Shengxiong long xinping Hubei Key Laboratory of Water Jet Theory and New Technology Wuhan UniversityWuhanHubei 430072China Hefei General Machinery Research Institute HefeiAnhui 230071China

To investigate the influence of operation parameters of abrasive water jet on surface roughness of carbon fiber reinforced plastic(CFRP),experimental studies were *** three-dimensional landscape of cutting front was reconstructed according to the measured data byμscan laser confocal *** spectral analysis was also adopted to study surface structure in *** is found that the morphology of cutting front is similar to that of other *** the smooth cutting zone,the fluctuation of amplitudes of surface profile is gentler,compared with that in the rough cutting *** lower part of the rough cutting zone was characterized by the periodical appearance of peaks and *** roughness of surface increases with the increase of *** in the smooth cutting zone and part of rough cutting zone,roughness increases with the increase of traverse *** the thickness of samples,in the smooth cutting zone,the roughness increases with the increase of *** dominant harmonic component in the surface profile is concentrated in a narrow range from 0 to 10 Hz,and the relatively higher density of frequency from 10 to 50 Hz is shown in the rough cutting zone,which is caused by the interaction between perpendicular abrasive water jet and reflect jet.

关键词： abrasive water jet Fourier analysis roughness carbon fiber reinforced plastic

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射流泵极限工况下空化流动

机械工程学报 2009年第12期45卷 59-64页

作者：龙新平姚昊赵建福武汉大学动力与机械学院武汉430072 秦山核电联营有限公司机械动力处海盐314300 中国科学院力学研究所国家微重力实验室北京100190

极限工况发生时,液体射流泵喉管中段至末端的汽液两相空化流动为均相泡状流。基于定常、等温及水平流动假设和Wood声速公式,导出极限工况发生时射流泵喉管中段至末端一维均相泡状流的控制方程组。依据该控制方程结合射流泵壁面沿程压力... 详细信息

极限工况发生时,液体射流泵喉管中段至末端的汽液两相空化流动为均相泡状流。基于定常、等温及水平流动假设和Wood声速公式,导出极限工况发生时射流泵喉管中段至末端一维均相泡状流的控制方程组。依据该控制方程结合射流泵壁面沿程压力测试结果,计算喉管中段至末端液汽两相流动的马赫数。从喉管的中段至末端液汽两相流动的马赫数逐渐增加,在压力最低点附近达到最大,其最大值为0.94,十分接近1。进一步分析表明,极限工况发生时,射流泵喉管中段至末端液汽两相空化流表现为两相临界流动,其流速达到当地液汽两相流声速,流动出现臃塞,从而导致一定工作压力下吸入流量不再随出口压力的降低而增加,而是保持不变。揭示射流泵极限工况发生的机理,对其深入研究具有重要意义。

关键词：射流泵空化极限工况汽液两相流临界流 Wood声速公式

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射流泵空化影响因素的数值分析

应用基础与工程科学学报 2009年第3期17卷 461-469页

作者：龙新平程茜韩宁武汉大学动力与机械学院湖北武汉430072 流体机械与动力工程装备技术湖北省重点试验室湖北武汉430072

基于URANS方法,对射流泵内空化流动进行了数值模拟.采用喷嘴出口处的脉动压强及泵内平均汽相份额为指标分析了不同工作参数、结构参数和初始含气量对射流泵空化影响.结果表明,对同一射流泵,当初始含气量相同时,随着工作压力的升高或出... 详细信息

基于URANS方法,对射流泵内空化流动进行了数值模拟.采用喷嘴出口处的脉动压强及泵内平均汽相份额为指标分析了不同工作参数、结构参数和初始含气量对射流泵空化影响.结果表明,对同一射流泵,当初始含气量相同时,随着工作压力的升高或出口压力的降低,空化加剧;对同一射流泵在相同工作参数下,水体中初始含气量越高,空化越严重;对不同面积比的射流泵,当初始气含量和工作参数相同时,面积比越小,空化越严重.

关键词：射流泵空化脉动压强 FLUENT

空化对叶顶间隙泄漏涡演变特性及特征参数影响的大涡模拟研究

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力学学报 2021年第5期53卷 1268-1287,I0001页

作者：程怀玉季斌龙新平槐文信武汉大学水资源与水电工程科学国家重点实验室武汉430072

利用大涡模拟方法及一个考虑气核效应的欧拉-拉格朗日新空化模型,对绕NACA0009水翼叶顶间隙泄漏涡(top-leakage vortex,TLV)及其空化流动开展了高精度的模拟,结果显示数值模拟与实验吻合较好.在此基础上进一步讨论了不同间隙大小对TLV... 详细信息

利用大涡模拟方法及一个考虑气核效应的欧拉-拉格朗日新空化模型,对绕NACA0009水翼叶顶间隙泄漏涡(top-leakage vortex,TLV)及其空化流动开展了高精度的模拟,结果显示数值模拟与实验吻合较好.在此基础上进一步讨论了不同间隙大小对TLV空化的演变行为及其发生前后TLV强度、气核分布以及切向速度分布等特征参数的变化规律,分析了TLV空化对TLV演变行为及其特征参数的影响机制.结果表明,空化发生后,TLV的强度主要受片空化演变行为的影响,TLV空化对其自身强度的影响较小.此外,间隙越小,片空化越不稳定,TLV的强度也会呈现相应的准周期性波动.随着间隙的逐渐增大,片空化强度逐渐减小,其不稳定性也逐步减弱,TLV强度逐渐恢复至无空化时的水平,其波动也会逐渐减小.空化对涡心处气核分布会产生较为明显的影响,其影响程度取决于空化发生后TLV在空间上的稳定性以及TLV空化的强度.此外,空化发生后,TLV半径会在一定程度上增大,且在空化区域外围形成"类刚体旋转"的切向速度分布特性,其形成原因主要是空化生长引起的膨胀过程以及流动的黏性作用.

关键词：空化叶顶间隙泄漏涡空化模型气核

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多孔喷嘴射流泵流动模拟与涡结构分析

排灌机械工程学报 2012年第2期30卷 136-140,152页

作者：龙新平姚鑫杨雪龙武汉大学动力与机械学院湖北武汉430072

基于有限体积法和Realizable k-ε湍流模型,对多孔喷嘴射流泵内部流场进行数值模拟和分析,并与试验结果进行对比,验证了数值模拟的可靠性.引入涡动力学理论对喉管内部工作流体和被吸流体的混合机理进行分析,研究了喉管内部流向涡和展向... 详细信息

基于有限体积法和Realizable k-ε湍流模型,对多孔喷嘴射流泵内部流场进行数值模拟和分析,并与试验结果进行对比,验证了数值模拟的可靠性.引入涡动力学理论对喉管内部工作流体和被吸流体的混合机理进行分析,研究了喉管内部流向涡和展向涡的分布及其峰值沿流向的变化.结果表明:多孔喷嘴结构能够加快工作流体和被吸流体的混合,提高射流泵的效率;射流泵喉管内的涡结构对工作流体和被吸流体的混合有重要影响,相对流向涡而言,展向涡的强度较大,在喉管内的衰减较为平缓;在射流泵中,对两股流体起主要掺混作用的是流向涡,其强度和衰减的速率决定了混合效率;在涡量一定的情况下,流向涡越强,衰减越快;展向涡结构越小,越能加速喉管中的混合,从而提高泵的效率;喉管内涡的分布表明,位于喷嘴中心的出口可能导致较大的损失,各孔喷嘴出口应优先沿圆周方向布置.

关键词：多孔喷嘴射流泵喷嘴结构流场分析流向涡展向涡

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轴流式喷水推进泵内涡与空化相互作用

哈尔滨工程大学学报 2020年第7期41卷 951-957页

作者：徐顺龙新平季斌李贵斌武汉大学水资源与水电工程国家重点实验室湖北武汉430072 中国船舶设计研究院喷水推进技术国家重点实验室上海200011

喷水推进泵内空化的发生直接影响推进效率,尤其是进入性能陡降工况,针对目前对该工况下喷水推进泵内涡与空化相互作用认知不足,极需从机理方面展开研究。本文采用分离涡流模拟(detached eddy simulation,DES)湍流模型Zwart-Gerber-Belam... 详细信息

喷水推进泵内空化的发生直接影响推进效率,尤其是进入性能陡降工况,针对目前对该工况下喷水推进泵内涡与空化相互作用认知不足,极需从机理方面展开研究。本文采用分离涡流模拟(detached eddy simulation,DES)湍流模型Zwart-Gerber-Belamri(ZGB)空化模型对性能陡降工况下的喷水推进泵内部空化流场进行数值模拟,并结合柱坐标系下的涡量输运方程对喷水推进泵内涡与空化的相互作用机理进行分析。研究表明:数值计算的空化性能曲线与实验测量结果吻合较好;涡线拉伸扭曲项与涡量分布密切相关;斜压矩项和膨胀项主要集中在汽液交界面处,会引起涡量场的重新分布,并且膨胀项的量级要大于斜压矩项;在间隙处,粘性耗散性量级较大,粘性耗散项的作用不可忽略。

关键词：喷水推进泵空化水力性能数值模拟涡量输运临界空化柱坐标系