COMPUTATION OF TURBULENT FLOW AND HEAT TRANSFER IN LARGE RADIUS 90－DEGREE CIRCULAR BENDS

ＣＯＭＰＵＴＡＴＩＯＮＯＦＴＵＲＢＵＬＥＮＴＦＬＯＷＡＮＤＨＥＡＴＴＲＡＮＳＦＥＲＩＮＬＡＲＧＥＲＡＤＩＵＳ９０－ＤＥＧＲＥＥＣＩＲＣＵＬＡＲＢＥＮＤＳＭ．Ｊ．Ｗａｎｇ（ＴｅｃｈｎｉｓｃｈｅＵｎｉｖｅｒｓｉｔａｔＭｕｎｃｈｅｎ，ＢＲＤ）ＳｕＭｉｎｇ－...     

AN INTEGRATEDC METHOD FOR COMPUTING COMPUTING THE INTERNAL AND EXTERNAL VISCOUS FLOW FIELD AROUND THE DUCTED PROPULSOR BEHIND AN AXISYMMETRIC BODY

ＡＮＩＮＴＥＧＲＡＴＥＤＣＭＥＴＨＯＤＦＯＲＣＯＭＰＵＴＩＮＧＣＯＭＰＵＴＩＮＧＴＨＥＩＮＴＥＲＮＡＬＡＮＤＥＸＴＥＲＮＡＬＶＩＳＣＯＵＳＦＬＯＷＦＩＥＬＤＡＲＯＵＮＤＴＨＥＤＵＣＴＥＤＰＲＯＰＵＬＳＯＲＢＥＨＩＮＤＡＮＡＸＩＳＹＭＭＥＴＲＩＣＢＯＤ...     

BOUNDARY LAYER EFFECTS ON SOLID PARTICLE MOTION AND EROSIVE WEAR

ＢＯＵＮＤＡＲＹＬＡＹＥＲＥＦＦＥＣＴＳＯＮＳＯＬＩＤＰＡＲＴＩＣＬＥＭＯＴＩＯＮＡＮＤＥＲＯＳＩＶＥＷＥＡＲＬｉｕＸｉａｏ－ｂｉｎｇ（ＳｉｃｈｕａｎＩｎｓｔｉｔｕｔｅｏｆＴｅｃｈｎｏｌｏｇｙ，Ｃｈｅｎｇｄｕ６１１７４４，Ｐ．Ｒ．Ｃｈｉｎａ）Ｃｈｅｎ...     

A HYBRID METHOD FOR THE SIMULATION OF WAVE SPECTRUM TRANSFORMATION AND BREAKING PHENOMENA ON A SLOPE

ＡＨＹＢＲＩＤＭＥＴＨＯＤＦＯＲＴＨＥＳＩＭＵＬＡＴＩＯＮＯＦＷＡＶＥＳＰＥＣＴＲＵＭＴＲＡＮＳＦＯＲＭＡＴＩＯＮＡＮＤＢＲＥＡＫＩＮＧＰＨＥＮＯＭＥＮＡＯＮＡＳＬＯＰＥＬｉＹｕ－ｃｈｅｎｇ；ＤｏｎｇＧｕｏ－ｈａｉ（ＤｅｐａｒｔｍｅｎｔｏｆＣｉｖｉｌ...     

BLOCKAGE COEFFICIENT TECHNIQUE FOR SQUARE ENCLOSURE FLOW WITH NO THICKNESS SPACERS

ＢＬＯＣＫＡＧＥＣＯＥＦＦＩＣＩＥＮＴＴＥＣＨＮＩＱＵＥＦＯＲＳＱＵＡＲＥＥＮＣＬＯＳＵＲＥＦＬＯＷＷＩＴＨＮＯＴＨＩＣＫＮＥＳＳＳＰＡＣＥＲＳ￥ＹｕＬｉ－ｒｅｎ（Ｄｅｐｔ．ｏｆＨｙｄｒａｕｌｉｃｓａｎｄＳａｎｉｔａｒｙＥｎｇｉｎｅｅｒｉｎｇ，Ｓｃｈ...     

APPLICATION OF BODY－FITTED CURVILINEAR COORDINATE TRANSFORMATION IN 3－D SEEPAGE FLOW COMPUTATION

ＡＰＰＬＩＣＡＴＩＯＮＯＦＢＯＤＹ－ＦＩＴＴＥＤＣＵＲＶＩＬＩＮＥＡＲＣＯＯＲＤＩＮＡＴＥＴＲＡＮＳＦＯＲＭＡＴＩＯＮＩＮ３－ＤＳＥＥＰＡＧＥＦＬＯＷＣＯＭＰＵＴＡＴＩＯＮＦａｎｇＦａｎｇ－ｘｉｎ；ＱｉＬｉ；ＣｈｅｎＺｈａｏ－ｈｅ；ＰｅｎｇＹｕ（Ｓｃ...     

STOCHASTIC ANALYSES OF ADSORBING SOLUTE TRANSPORT IN HETEROGENEOUS UNSATURATED SOILS

ＳＴＯＣＨＡＳＴＩＣ　ＡＮＡＬＹＳＥＳ　ＯＦ　ＡＤＳＯＲＢＩＮＧ　ＳＯＬＵＴＥ　ＴＲＡＮＳＰＯＲＴ　ＩＮ　ＨＥＴＥＲＯＧＥＮＥＯＵＳ　ＵＮＳＡＴＵＲＡＴＥＤ　ＳＯＩＬＳＳＴＯＣＨＡＳＴＩＣＡＮＡＬＹＳＥＳＯＦＡＤＳＯＲＢＩＮＧＳＯＬＵＴＥＴＲＡＮＳＰ...     

THE TURBULENCE CHARACTERISITICS OF OPEN CHANNEL FLOW

ＴＨＥ　ＴＵＲＢＵＬＥＮＣＥ　ＣＨＡＲＡＣＴＥＲＩＳＩＴＩＣＳ　ＯＦ　ＯＰＥＮ　ＣＨＡＮＮＥＬ　ＦＬＯＷＴＨＥＴＵＲＢＵＬＥＮＣＥＣＨＡＲＡＣＴＥＲＩＳＩＴＩＣＳＯＦＯＰＥＮＣＨＡＮＮＥＬＦＬＯＷ￥ＷａｎｇＸｉｎｇ－ｋｕｉ（Ｄｅｐａｒｔ．ｏｆＨｙｄｒ...     

SECONDARY INSTABILITY WITH RESPECT TO SPATIAL GROWING THREE－DIMENSIONAL SUBHARMONIC DISTURBANCES IN BOUNDARY LAYER FLOW WITH SUCTION

ＳＥＣＯＮＤＡＲＹＩＮＳＴＡＢＩＬＩＴＹＷＩＴＨＲＥＳＰＥＣＴＴＯＳＰＡＴＩＡＬＧＲＯＷＩＮＧＴＨＲＥＥ－ＤＩＭＥＮＳＩＯＮＡＬＳＵＢＨＡＲＭＯＮＩＣＤＩＳＴＵＲＢＡＮＣＥＳＩＮＢＯＵＮＤＡＲＹＬＡＹＥＲＦＬＯＷＷＩＴＨＳＵＣＴＩＯＮ￥ＺｈａｏＧｅｎ...     

3-D TURBULENT FLOW SIMULATION FOR THE TAIL WATER CHANNEL

３－ＤＴＵＲＢＵＬＥＮＴＦＬＯＷＳＩＭＵＬＡＴＩＯＮＦＯＲＴＨＥＴＡＩＬＷＡＴＥＲＣＨＡＮＮＥＬＧｕａｎＪｉａｎ－ｙｏｎｇ；ＣｈｅｎＢｉ－ｈｏｎｇ（ＤａｌｉａｎＵｎｉｖｅｒｓｉｔｙｏｆＴｅｃｈｎｏｌｏｇｙ，Ｄａｌｉａｎ１１６０２３，Ｐ．Ｒ．Ｃｈｉｎａ...     

NUMERICAL PREDICTION OF BLADE FREQUENCY NOISE OF CAVITA- TING PROPELLER

The blade frequency noise of a cavitating propeller in a uniform flow is analyzed in the time domain. The unsteady loading (of a dipole source) and the sheet cavity volume (of a monopole source) on the propeller surface are calculated by a potential-based surface panel method. Then the time-dependent pressure and the cavity volume data are used as the input for the Fowcs Williams-Hawkings formulation to predict the acoustics pressure. The integration of the noise source is performed over the true blade surface rather than the ideal blade surface without thickness. The noise characteristics of the cavitating propeller are discussed. With the sheet cavitation, the thickness (cavitation) noise is larger than the loading noise and is the dominant noise source.The noise directivity is not as clear as that of the noise under a non-cavitation condition. The cavitation noise is attenuated mores lowly than the non-cavitation noise.     

PREDICTION OF PODDED PROPELLER CAVITATION USING AN UNSTEADY SURFACE PANEL METHOD

The unsteady sheet cavitation of podded propeller was predicted by using a surface panel method. The interaction between propeller and pod was treated with the iterative calculation of induced velocity potential, and the method of induced velocity potential can save a great deal of storage and computation time compared to the method of induced velocity. The induced velocity potential of unit singularity on every pod panel to every key blade panel and of unit singularity on every key blade panel and its wake panel to every pod panel were calculated when the key blade is at every angle position. Based on the wake model of the conventional single propeller, a new wake model of podded propeller was constructed. The propeller is analyzed only on the key blade in order to save computation time and memory space. The method can be used to calculate the hydrodynamics performance and cavitation of propeller in uniform and non-uniform inflows. It can give the unsteady force and cavitation shape of propeller. The propeller cavitation range determined by the present method agrees with the observation results of cavity image given in cavitation tunnel well, and this proves the practicability of the method.     

An integral calculation approach for numerical simulation of cavitating flow around a marine propeller behind the ship hull

In this paper, the unsteady cavitating turbulent flow around a marine propeller is simulated based on the unsteady Reynolds averaged Navier-Stokes(URANS) with emphasis on the hull-propeller interaction by an integral calculation approach, which means the propeller and hull are treated as a whole when the cavitating flow is calculated. The whole calculational domain is split to an inner rotating domain containing a propeller and an outer domain containing a hull. And the two split sections are connected together in ANSYS CFX by using the GGI interfaces and the transient rotor stator frame change/mixing model. The alternate rotation model is employed for the advection term in the momentum equations in order to reduce the numerical error. Comparison of predictions with measurements shows that the propeller thrust coefficient can be predicted satisfactorily. The unsteady cavitating flow around the propeller behind the ship hull wake shows quasi-periodic features including cavity inception, growth and shrinking. These features are effectively reproduced in the simulations which compare well to available experimental data. In addition, significant pressure fluctuations on the ship hull surface induced by the unsteady propeller cavitation are compared with experimental data at monitoring points on the hull surface. The predicted amplitudes of the first components corresponding to the first blade passing frequencies match well with the experimental data. The maximum error between the predictions and the experimental data for the pressure pulsations is around 8%, which is acceptable in most engineering applications.     

Simplified hydrodynamic models for the analysis of marine propellers in a wake-field

This paper presents a comparison among different hydrodynamic models for the analysis of the unsteady loads delivered by a marine propeller working in an axial, non-uniform inflow. Specifically, for a propeller subjected to a wake-field dominated by local high-frequency changes in space, the unsteady hydroloads predicted by the Nakatake formulation are compared with those given by the Theodorsen and Sears theories, respectively. Drawbacks and potentialities of these approaches are highlighted to assess a computationally efficient hydrodynamic solver for the analysis of operating conditions where propeller blades are significantly perturbed by a multi-harmonic onset-flow. Guidelines coming from this investigation may drive the choice of a fast and reliable unsteady propeller modeling that represents a good trade-off between accuracy of simulation and cost of computation within implementation in Computational Fluid Dynamics （CFD） solvers. The hydrodynamic formulations herein proposed are validated through numerical comparisons with the （accurate but computationally expensive） propeller loads predicted by a fully 3-D panel-method Boundary Element Method （BEM） solver, suited for the analysis of propellers operating in a complex hydrodynamic environment.     

Marine propellers performance and flow-field prediction by a free-wake panel method

A Boundary Element Method （BEM） hydrodynamics combined with a flow-alignment technique to evaluate blades shed vorticity is presented and applied to a marine propeller in open water. Potentialities and drawbacks of this approach in capturing propeller performance, slipstream velocities, blade pressure distribution and pressure disturbance in the flow-field are highlighted by comparisons with available experiments and RANSE results. In particular, correlations between the shape of the convected vortex- sheet and the accuracy of BEM results are discussed throughout the paper. To this aim, the analysis of propeller thrust and torque is the starting point towards a detailed discussion on the capability of a 3-D free-wake BEM hydrodynamic approach to describe the local features of the flow-field behind the propeller disk, in view of applications to propulsive configurations where the shed wake plays a dominant role.     

高负荷螺旋桨水动力性能试验研究

以某大型集装箱船高负荷螺旋桨为研究对象,分别采用大侧斜、反弯扭叶片和毂帽鳍等技术进行螺旋桨优化设计,以改善螺旋桨的空泡和水动力性能.设计了5型螺旋桨,分别在空泡水筒进行了模拟伴流场中的空泡和激振力试验,并在拖曳水池进行了敞水试验.试验结果表明,采用大侧斜可有效减小螺旋桨诱导船艉激振力;反弯扭叶片螺旋桨空泡性能较好,有较低的螺旋桨诱导船艉激振力水平;桨毂帽鳍可改善毂涡空泡,模型试验状态下可提高推进效率2%左右.     

螺旋桨非定常力的黏性数值分析

基于黏流的数值模拟技术在非均匀来流情况下对DTMB P4119桨所受的非定常力进行了分析.该桨已在DTMB用给定的非均匀轴向进流场做过非定常水动力测量,故本文计算用该进流场作为进流条件并把该试验结果用来验证.计算过程分析了网格数的收敛性. 非定常力的计算的预报结果,明显地反映了1阶,2阶及3阶叶频的轴承力幅值与进流阶调的耦合效应.通过计算结果与试验结果的对比,不论是非定常力的演变特征还是脉动幅度都与试验结果吻合良好.通过简单定性分析认为通过计算得到的非定常力预报螺旋桨线谱噪声误差将在3dB以内,比较理想.     

NUMERICAL SIMULATION OF A PODDED PROPULSOR IN VISCOUS FLOW

A podded propulsor in viscous flow is numerically simulated in this article.The region of fluid is divided into efficient calculation grids.The pressure and viscous force of blades,pod and strut are obtained as functions of an advance coefficient.The steady result is used as a base in the unsteady simulation to obtain a solution more quickly.The distributions of the thrust and torque fluctuations of the key blade in one revolution are obtained.The calculation results from the mixing plane on steady conditions are compared with those obtained from the sliding mesh model on unsteady conditions.The User-Defined Function(UDF)method is used to simulate the influence of ship hull on the non-uniform wake of the propeller.     

The design of propeller and propeller boss cap fins (PBCF) by an integrative method

Generally, after a marine propeller design, the propeller boss cap fins (PBCF) design concerns with an optimal selection of model test results, without a due consideration of the interaction between the PBCF and the propeller. In this paper, the PBCF and the propeller are considered as a whole system with their design as an integrative process, in which the concept of the increased loading in the blade root is incorporated. The load distribution on the blade becomes well-proportioned due to the increased loading in the blade root, and it is advantageous to the reduction of the vibratory force and the blade tip vortex. The blade root area is stronger in withstanding forces, and is not easy to be vibrated, therefore, the increased loading there is beneficial to the noise reduction. The disadvantage of the increased loading in the blade root is the generation of the hub vortex behind the boss cap, but the hub vortex can be broken up by the energy saving hydrodynamic mechanism of the PBCF. The integrative design method introduced in this paper can provide a higher efficiency for propellers under the same design conditions. In this paper, an integrative propeller and PBCF design method including the theoretical design and the numerical optimization design is proposed, based on the potential flow theory, the CFD tools, the improved particle swarm optimization algorithm, and the model tests. A propeller with the PBCF is designed based on the method of integrated increased loading in the blade root for a cargo vessel in this paper. The cavitation tunnel model test results show that the propeller and the PBCF thus designed enjoys a higher efficiency, and the design method is effective, reliable and practical.     

ON THE RELATION BETWEEN CAVITATION INCEPTION AND FLOW PATTERN ON PROPELLER BLADES

Oil flow visuallization on the model propellers with and without tripping devices atthe leading edge is revealed in this paper. Roughing leading edge with sand blasting was to simu-late the flow at full-scale condition. The observations of cavitation inception and the detection ofcavitation erosion were made in uniform and non-uniform flow respectively so as to consider theeffects of flow pattern on cavitation inception and to investigate the causes of difference in thelocations of cavitation erosion between model propeller and prototype. In addition, calculationsof the pressure distributions and the behaviour of boundary layer on the propeller blade were alsodone by using theoretical method. It is necessary to gain a better understanding of cavitation in-ception of the propeller.