慢扩张旋涡破裂位置的确定

在慢扩张的假设下给出一类旋涡发展的解析表达式,讨论了解的性质,在一定情况下会出现泡型区和涡破裂,讨论了扩张角及旋转速度对涡破裂位置的影响。     

STUDY ON THE FUEL AIR MIXING INDUCED BY A SHOCK WAVE PROPAGATING INTO A H_2-AIR INTERFACE

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｆｕｅｌａｉｒｍｉｘｉｎｇｉｎａｓｈｅａｒｌａｙｅｒｆｌｏｗｉｓａｎｉｍｐｏｒｔａｎｔｐｒｏｂｌｅｍｉｎｓｔｕｄｙｉｎｇｃｏｍｐｒｅｓｓｉｂｌｅｆｌｏｗａｎｄｓｕｐｅｒｓｏｎｉｃｃｏｍｂｕｓｔｉｏｎ ,ｓｕｃｈａｓｆｕｅｌｄｉｆｆｕｓｉｏｎａｎｄｍｉｘｉｎｇｉｎａＳｃｒａｍｊｅｔ[1].Ｒｏｓｈｋｏ[2 ]ｓｔｕｄｉｅｄｅｘｐｅｒｉｍｅｎｔａｌｌｙｔｈｅｐｈｅｎｏｍｅｎｏｎｏｆｆｕｅｌａｉｒｍｉｘｉｎｇｉｎａｓｕｂｓｏｎｉｃｓｈｅａｒｆｌｏｗａｎｄｆｏｕｎｄｌａｒｇｅ ,ｃｏｈ…     

The Decay of Swirling Flows in a Type of Cross-Section-Varying Pipes

ＩｎｔｒｏｄｕｃｔｉｏｎＳｗｉｒｌｉｎｇｆｌｏｗ (ｏｒｓｐｉｒａｌｆｌｏｗ )ｉｓｗｉｄｅｌｙｕｓｅｄｉｎｉｎｄｕｓｔｒｙ ,ｅ.ｇ .ｉｎｊｅｔｔｅｃｈｎｏｌｏｇｙ ;ｃｏｍｂｕｓｔｉｏｎｔｅｃｈｎｏｌｏｇｙ ;ｃｙｃｌｏｎｅ/ｈｙｄｒｏｃｙｃｌｏｎｅｓｅｐａｒａｔｏｒｓ;ｐｎｅｕｍａｔｉｃｔｒａｎｓｐｏｒｔａｔｉｏｎｅｔｃ .Ｓｗｉｒｌｉｓｃｏｍｍｏｎｌｙｉｍｐａｒｔｅｄｔｏｆｌｏｗｓｅｎｔｅｒｉｎｇｆｕｒｎａｃｅｓａｎｄｃｏｍｂｕｓｔｏｒｓｉｎｏｒｄｅｒｔｏｅｎｈａｎｃｅｆｌａｍｅｓｔａｂｉｌｉｔｙａｎ…     

有旋湍流场中湍流模型应用的研究

本文通过对三种双时间尺度湍流模型的理论分析，选择出最合理的模型，并在其基础上引入非线性Reynolds应力─应变关系式及梯度Richardson数修正，对有旋湍流场进行计算，其结果表明，双时间尺度模型能较好地预测出复杂湍流场中平均物理量的分布，尤其对回流区大小和强度的预测较常规k-ε模型结果有很大改进。因此，本文将双时间尺度模型应用于旋流燃烧器中气体颗粒两相流动的计算。     

离心风机梯形截面蜗壳内旋涡流动的数值分析

本文求解时均N-S方程和“Baldwin-Lomax”湍流模式,使用基于时间推进法的Jameson格式计算方法,对一离心风机的梯形截面蜗壳内部流场进行了数值模拟。计算结果表明,在蜗壳各径向截面上都存在着一个旋转方向相反、强度交替变化的涡对。该涡对会随着径向截面位置与蜗壳运行工的变化发生复杂的变化。对该涡对演化细节的研究有助于探讨蜗壳内流动损失的一些机理。     

Viscoelastic swirling flow with free surface in cylindrical chambers

The flow of a viscoelastic liquid driven by the steadily rotating bottom cover of a cylindrical cup is investigated. The flow field and the shape of the free surface are determined at the lowest significant orders of the regular domain perturbation in terms of the angular velocity of the bottom cap. The meridional field superposed on a primary azimuthal field shows a structure of multiple cells. The velocity field and the shape of the free surface are strongly effected by the cylinder aspect ratio and the elasticity of the liquid. The use of this flow configuration as a free surface rheometer to determine the first two Rivlin-Ericksen constants is shown to be promising.Nomenclature R, ,Z Coordinates in the physical domain D - , , Coordinates in the rest stateD ₀ - r, ,z Dimensionless coordinates in the rest stateD ₀ - Angular velocity - Zero shear viscosity - Surface tension coefficient - Density - Dimensionless surface tension parameter - ₁, ₂ The first two Rivlin-Ericksen constants - Stream function - Dimensionless second order meridional stream function - ^* Dimensionless second normal stress function - 2 Dimensionless sum of the first and second normal stress functions - N ₁,N ₂ The first and second normal stress functions - n Unit normal vector - D Stretching tensor - A _n nth order Rivlin-Ericksen tensor - S Extra-stress - u Velocity field - U Dimensionless second order meridional velocity field - V Dimensionless first order azimuthal velocity field - p Pressure - Modified pressure field - P Dimensionless second order pressure field - J Mean curvature - a Cylinder radius - d Liquid depth at rest - D Dimensionless liquid depth at rest - h Free surface height - H Dimensionless free surface height at the second order     

Effect of Interphase Heat Transfer on the Stability of a Turbulent Multicomponent Flow in a Vortex

The parameters of an axisymmetric turbulent two-phase swirling flow of a viscous heat-conducting gas containing a liquid dispersed phase in the presence of water vapor condensation on the particles are calculated. For the dispersed phase, a model taking into account the variation of the vapor concentration and the particle size due to condensation or evaporation is proposed. The distributions of the parameters of the basic unperturbed flow obtained numerically are used in the numerical solution of the linear problem of hydrodynamic stability within the time-dependent formulation. The parameters of small-amplitude harmonic perturbations propagating along the vortex axis are investigated in the linear formulation. A significant effect of heat release in the gas due to water vapor condensation on the parameters of the neutral perturbations and the neutral-stability curves is detected.     

利用旋风炉玻璃化处理垃圾焚烧飞灰实验研究

在自行设计的旋风炉实验台上对焚烧飞灰进行玻璃化熔融实验,系统研究了焚烧飞灰熔融前后微观形貌、灰渣中重金属特性和浸出特性。实验结果表明,焚烧飞灰旋风熔融后成黑色的脆硬玻璃态熔渣,表层呈浅黄色。在熔渣中N i、Cr的固溶率最高,均超过95%以上;低熔点重金属多数挥发至熔融烟气和熔融烟道飞灰颗粒中,Cd的固溶率仅有21%,Pb和Zn部分固溶于玻璃态熔渣中,两者固溶率可达42%以上。Cu和As的固溶率分别为37%和18%。熔融后的玻璃态熔渣重金属浸出率明显低于熔融前的焚烧飞灰,且均低于美国EPA的标准限值。     

3D tangentially injected swirling recirculating flow in a nozzle with a slotted‐tube—Effects of groove parameters

A numerical prediction for 3D swirling recirculating flow in an air‐jet spinning nozzle with a slotted‐tube is carried out with the realizable k–ε turbulence model. The effects of the groove parameters on the flow and yarn properties are investigated. The simulation results show that some factors, such as reverse flow upstream of the injector, vortex breakdown downstream of the injector, corner recirculation zone (CRZ) behind the step and vortex ring in the groove caused by the groove geometric variation, are significantly related to fluid flow, and consequently to yarn properties. With increasing groove height, the length of the CRZ increases, while the initial vortex ring in the groove decreases and a same direction rotating vortex forms in the bottom of the groove. Similarly, as the groove width increases, the extent of both vortex breakdown in downstream of the injectors and the vortex ring in the groove increases slightly, whereas the CRZ lengths in stream‐wise direction decrease. Some factors, such as the negative tangential velocities, the size of the vortex rings in the grooves and the CRZ, are constant for nozzles with different groove lengths. Copyright © 2009 John Wiley & Sons, Ltd.