静止浅水环境中铅垂紊动射流的试验研究

对静止均匀浅水域中的铅垂紊动射流进行了试验研究，得到了水面的隆起高度与射流出口单位能量和相对水深的函数关系，验证了隆起高度满足高斯分布，具有自相似性，并给出了统一表达式；借助于三维测速仪，得到了射流中心平面流场，结果表明射流中线流速的衰减比自由射流为快，随着射流出口流量的增加，射流出口处涡量亦增大。     

射流掺气对冲刷的影响

通过对射流掺气与不掺气时基岩冲刷的对比试验，研究了掺气对射流冲刷的影响。试验结果表明：掺气总是使冲坑减小，冲坑深度随掺气浓度的增加而递减的规律可表示为幂函数关系。当入射流速和水舌厚度相同时，随着下游水垫深度的增加，掺气对射流冲刷能力的减弱程度也增加；当水舌厚度和水垫深度相同时，对不同的入射流速，在本次试验范围内，掺气对射流冲刷能力的减弱程度是相同的。掺气对冲坑形态并没有实质性的影响，冲坑的宽深比随冲坑深度的减小而增大，无论造成冲坑深度减小的原因是掺气、降低流速还是减少入射水舌厚度，其变化规律都可用相同的直线关系表示。     

跌坎型底流消能工淹没射流掺气浓度分布规律试验

采用水力学试验的方法,测量了跌坎型底流消能工在不同流量、跌坎深度下,淹没射流区的掺气浓度值,并通过对比分析得到入池流量与跌坎深度对该区域掺气浓度沿程分布的影响规律。试验结果表明:跌坎深度一定时,掺气浓度随入池流量的增加而增加;流量一定时,跌坎深度越大,掺气浓度越小;不论跌坎深度、入池流量改变与否,该区域掺气浓度沿射流流程均呈现先增大后减小的规律;经综合分析入池流量、跌坎深度、射流流程与掺气浓度的关系后,文中给出了射流轴线处掺气浓度计算的经验公式,该公式计算值与实测值基本吻合。     

跌坎型掺气槽过流的掺气特性

本文在分析实测资料的基础上，探讨了无挑角跌坎型掺气槽空腔区水舌的掺气特性，并重点研究了射流水舌的掺气超始流速，掺气层厚度，断面浓度分布以及通气量等参数的理论预测。     

平面掺气散裂射流特性

本文根据部分掺气散裂射流的特性，提出了相应的物理模式与数学模式，并通过简化与相似分析得到了掺气散裂射流的半宽，水挟气泡区的半宽，水核区的半宽和射流掺混区与水挟气泡区边界处的含气浓度随射流初始条件的变化，并将计算结果与实验结果进行了比较，结果表明，两者甚为一致。     

同轴直射流与旋转射流组合的双射流湍流流场数值模拟

摘要：直射流与旋转射流分别具有能量传递距离长与能量传递分布面积大的优点，为了尽可能的提高射流能量利用，本文提出了结合两者优点的同轴直射流和旋转射流组成的新型双射流。对淹没条件下的组合双射流流场特性，进行数值模拟研究。采用RNGκ-ε模型和高精度QUICK离散格式，得出了不同速度组合下双射流流场的直射流轴心速度衰减和旋转射流旋转速度衰减规律，速度矢量图，量化分析了射流结构对流场结构的影响。计算结果表明，在喷嘴压降一定时，存在三种轴心速度衰减曲线，当旋转射流轴向速度高于门限速度的情况下，射流衰减速度最慢。另外，直射流与旋转射流轴心衰减曲线存在很大差异，要提高双射流能量利用，内外喷嘴的流量分配至关重要。     

外凸型阶梯式陡坡段掺气和动压特性

为了探讨溢洪道不连续外凸型阶梯陡坡段的掺气和动水压强特性,开展了坡度为1∶3阶梯陡坡段的掺气和动水压强水力模型试验。研究表明:受外凸型阶梯突体的影响,其阶梯陡坡段水流未掺气区长度比常规连续的内凹型阶梯陡坡段缩短,其水面掺气断面下游的陡坡段壁面水流掺气浓度较高和沿程增大,掺气浓度随阶梯高度增大而增加,随单宽流量增大而减小,陡坡段壁面的抗空蚀性能明显提高;阶梯陡坡段壁面动水压强随阶梯高度和单宽流量增大而增加,在阶梯高度a≤0.6 m、单宽流量q≤30 m~3/(s·m)试验条件范围内,陡坡段水面掺气断面下游的阶梯壁面动水压强值为其相应断面流速水头的45%之内。     

近水面淹没喷嘴射流流场特性的实验研究

本文对喷嘴在近自由水面情况下所形成的近水表面一层射流流场进行了系列测试，研究了不同情况下时均速度的纵向衰减及沿横向分布等特性，以及自由水面对其特性的影响。在实验的基础上，总结归纳出时均速度的纵向衰减规律，可供工程上应用。     

掺气水射流的空化及其应用

基于两相流体动力学的理论，建立空蚀射流切割装置中短管内的压力变化梯度的基本方程式；通过求解不同流速与不同掺气量时的短管内压力变化结果，分析了初始掺气率和水流流速对短管内压力坡降的影响；为增高水射流的切割效率提供理论依据；研究表明，若水流马赫数接近于1，短管内将产生巨大的压降，促使出口水流产生空化，通过利用高速水流并控制吸入适量空气，形成的空蚀流可提高水射流的切割效率。     

不同水流结构区掺气浓度分布规律试验研究

采用水力学模型试验的方法,通过改变跌坎深度、入射角度、入池流量观测跌坎消力池内不同水流结构区掺气浓度的分布规律,通过控制变量法,对试验数据进行对比分析。试验结果表明:对各水流结构区掺气浓度分布规律影响最大的是入池流量,其次是跌坎深度,而入射角度的影响最小。其中随着入池流量的增加,底滚回流区、冲击区、淹没射流区、附壁射流区、面回流区的掺气浓度都明显增加。随着跌坎深度的增加,底滚回流区、冲击区、淹没射流区的掺气浓度减小,附壁射流区和面回流区的掺气浓度变化不大。随着入射角度的增加,底滚回流区和冲击区的掺气浓度略微增加,淹没射流区的掺气浓度减小,附壁射流区和面回流区的掺气浓度变化不大。     

水下高速气体射流的实验研究

本文对高速空气射流在受限约束下的动力学行为进行了实验研究.通过流动可视化揭示了高速空气射流在单筒和同心筒发射筒底部滞止、反转、而后向上绕经航行体或同心筒间隙向上喷入水中的演化过程.主要观察了单筒底部有无导流锥、同心筒三种间隙在不同压比和不同流量下的气水两相流态,并测量了航行体与发射筒的壁面压力分布.给出了航行体壁表面压力的动态变化规律,和沿轴向的分布规律.     

水下气体射流初期数值研究

本文提出了一种新的水下气体射流的数学物理模型，并成功地将位标函数方法应用于水下气体射流气水交界面求解，数值模拟了水下气体射流初期的流动演化和气水相互作用特性，得到了气水全耦合的水下气体射流喷射初期的流场形态及其演化过程，定性结论与实验吻合。     

Dilution characteristics of dual buoyant jets in wavy cross-flow environment

Due to the difference in density between the discharge effluent and coastal water, partially treated wastewater is often discharged into the marine environment as a buoyant jet via submarine outfalls with multiport diffusers. The dilution characteristics of effluent discharge (dual buoyant jets) in a wavy cross-flow environment were studied in a laboratory. The planar laser-induced fluorescence technique was used to obtain the concentration data of the jets. The effects of different environmental variables on the diffusion and dilution characteristics of the jets were examined through physical experiments, dimensional analysis, and empirical formulations. It was found that the dilution process of the dual jets could be divided into two components: the original jet component and the effluent cloud component. The jet-to-current velocity ratio was the main parameter affecting the concentration levels of the effluent cloud. The merging of the two jets increased the jet concentration in the flow field. When the jets traveled further downstream, the axial dilution increased gradually and then increased significantly along the axis. Under the effects of strong waves, the concentration contours branched into two peaks, and the mean dilution became more significant than under the effects of weak waves. Therefore, the dilution of the effluent discharge was expected to be significant under strong wave effects because the hydrodynamic force increased. A dilution equation was derived to improve our understanding of the dilution process of buoyant jets in a wavy cross-flow environment. This equation was used to determine the influences of the jet-to-current velocity ratio, wave-to-current velocity ratio, and Strouhal number on the minimum jet dilution. It revealed that the wave and buoyancy effects in effluent discharges were significant.     

静止浅水环境中水平圆形浮力射流稳定性的数值研究

给出描述考虑浮力效应的热污水水平圆形浮力射流的数学模型，采用Balasubra-manian等（1978）的实验资料进行检验，计算结果和实验资料的吻合证明了模型和方法的有效性。在此基础上给出静止环境中水平圆形浮力射流稳定性的条件和表面最小稀释度的经验公式。     

喷管不同摆角对水下发射导弹受力的影响

论文研究了带摆喷管推力矢量控制系统的导弹水下垂直发射时,不同喷管摆角对三维水气流场的非定常发展变化过程及对导弹受力的影响。采用燃气泡物理模型,通过水气流场的耦合计算研究燃气与水的相互作用,运用欧拉-拉格朗日和时间步进的方法跟踪燃气泡自由面。以三维欧拉方程为控制方程对喷管和燃气泡内的三维气流场进行数值计算,根据燃气泡不断运动变化的交界面生成贴体动网格,在贴体坐标系下采用无波动、无自由参数、耗散的差分格式(NND差分格式)数值求解三维气流场。采用势流理论,以拉普拉斯方程为控制方程,利用三维Hess-Smith方法数值求解了导弹与燃气泡周围的三维水流场。给出了不同时刻泡形的变化,气流场内马赫数、压力的演变规律,导弹受力及力矩。通过多个工况的对比计算,研究了喷管摆角对导弹受力及水气流场的影响。     

Expansion characteristics of twin combustion gas jets with high pressure in cylindrical filling liquid chamber

To deal with the problem of how to control the interior ballistic stability in the bulk-loaded liquid propellant gun, the expansion and mixing process of the twin combustion-gas jets with high temperat...     

Scour process caused by multiple subvertical non-crossing jets

The scour process induced by plunging jets is an important topic for hydraulic engineers. In recent decades, several researchers have developed new strategies and methodologies to control the scour morphology, including different jet arrangements and structures located in the stilling basin. It has been found that multiple jets can cause less scouring than single plunging jets. Based on this evidence, this study aimed to investigate the equilibrium morphology caused by multiple non-crossing jets. A dedicated laboratory model was built and experimental tests were carried out under different combinations of jet inclination angles, by varying the tailwater level and the virtual crossing point location, which was set below the original channel bed level. It was experimentally shown that the equilibrium scour morphology depends on the jet discharge, the differences in non-crossing jet inclination angles, the downstream water level, and the distance of the virtual crossing point from the original channel bed level. In particular, the last parameter was found to be one of the most influential parameters, because of the resulting flow patterns inside the water body. Furthermore, the analysis of experimental evidence allowed for a complete and detailed classification of the scour hole typologies. Three different scour typologies were distinguished and classified. Finally, based on previous studies, two novel relationships have been proposed to predict both the maximum scour depth and length within a large range of hydraulic and geometric parameters.     

超高压水射流冲击岩石的流固耦合分析

根据流固耦合理论，建立了超高压水射流冲击破岩系统的数值分析理论模型。水射流采用标准k-ε双方程模型和控制体积法，岩石采用各向同性弹性介质和有限元法，给出了水射流与岩石耦合的数值算法。并按建立的理论模型计算了岩石在水射流速度为316.2m/s、447.2m/s、547.7m/s、632.5m/s冲击下流场规律和岩石内部的应力分布，为超高压水射流破岩机理的研究提供一种新的数值方法。     

Numerical study of spike characteristics due to the motions of a non-spherical rebounding bubble

The boundary integral method(BIM) is used to simulate the 3-D gas bubble, generated within the two bubble pulsation periods in proximity to a free surface in an inviscid, incompressible and irrotational flow. The present method is well validated by comparing the calculated shapes of the bubble and the free surface with both the experimental results and the numerical ones obtained by the Axisymmetric BIM code. The expansion, the collapse of the gas bubble and the further evolution of the rebounding non-spherical bubble are simulated. The various variation patterns of the free surface spike and the bubble centroid for different standoff distances, the buoyancy parameters and the strength parameters are obtained to reveal the nonlinear interaction between the bubble and the free surface. The amplitude of the second maximum bubble volume and the four typical patterns of the bubble jet and the free surface spike are examined in the context of the standoff distance. The large buoyancy is used to elevate the spray dome rather than the free surface spike.     

A COUPLING MODEL OF WATER FLOWS AND GAS FLOWS IN EXHAUSTED GAS BUBBLE ON MISSILE LAUNCHED UNDERWATER

The gas and water flows during an underwater missile launch are numerically studied. For the gas flow, the explicit difference scheme of Non-oscillation and Non-free-parameter Dissipation (NND) is utilized to solve the Euler equations for compressible fluids in the body-fitted coordinates. For the water flow, the Hess-Smith method is employed to solve the Laplace equation for the velocity potential of irrotational water flows based on the potential theory and the boundary element method. The hybrid Eulerian-Lagrangian formulation for the free boundary conditions is used to compute the changes of the free surface of the exhausted gas bubble in time stepping. On the free surface of the exhausted gas bubble, the matched conditions of both the normal velocities and pressures are satisfied. From the numerical simulation, it is found that the exhausted gas bubble grows more rapidly in the axial direction than in the radial direction and the bubble will shrink at its "neck" finally. Numerical results of the movement of the shock wave and the distribution of the Mach number and the gas pressure within the bubble were presented, which reveals that at some time, the gas flow in the Laval nozzle is subsonic and the gas pressure in the nozzle is very high. Influences of various initial missile velocities and chamber total pressures and water depths on both the time interval when the gas flow in the nozzle is subsonic and the peak of the gas pressure at the nozzle end were discussed. It was suggested that a reasonable adjustment of the chamber total pressure can improve the performance of the engine during the underwater launch of missiles.