密度（kg / m 3）

动态粘度（kg / ms）

RPM

12 r / m

18 r / m

24 r / m

30 r / m

36 r / m

42 r / m

密度

目标

压力值（times;10 6 Pa）

12 r / m

18 r / m

24 r / m

30 r / m

36 r / m

42 r / m

目标

压力值（times;10 6 Pa）

12 r / m

18 r / m

24 r / m

30 r / m

36 r / m

4

Flow Field Analysis of Cutter Head for Cutter Suction Dredgers

Abstract

For a cutter suction dredger, exploring slurry formation mechanism plays an important role for improving the dredgerrsquo;s efficiency and performance. In order to optimize the dredgerrsquo;s working parameters, the flow field is simulated for the cutter head of a cutter suction dredger in this study. First, Cutterrsquo;s 3D model is constructed by 3D Modeling software after necessary parameters are collected according to the designing 2D geometric drawing and related empirical contour curves. Then import the model to CFD for analysis, numerically simulate the cutterrsquo;s flow field in different working conditions so as to achieve the velocity and pressure distribution in and around the cutter head. And based on the simulation result, the optimized working point can be found in terms of equipment service life, environment protection and energy consumption.

1 Introduction

Cutter suction dredger is increasingly widely used worldwide for its wide depth range, good soil adaptability and high working efficiency, and it can continuously complete dredging, discharging and slurry treatment processes one time. Slurry formation around the suction mouth is related to several factors including the soil property, dredgerrsquo;s structural and operational parameters. And constructional parameters are type of the cutter, suction mouthrsquo;s shape and position and others. The operational ones are composed of cutter rotational speed, swing speed and pump rotational speed and so forth.

Sand or soil is cut down and mixed with water into slurry as result of the cutterrsquo;s rotation and stir. Sands will be crushed into particles in different sizes, some with large diameters will settle to the water stream bottom, the particles of small sizes will flow into the water. So the volume of the sand entering water is related with the sand crushing degree. The slurry will be partly or fully sucked into the suction mouth depending on the suction force. The movement of the particles can be simplified as spiral movement for the combination of the diffuse movement by the centrifugal force caused by the rotating cutter head and the forward movement approaching the suction mouth because of the pumprsquo;s suction.

Most dredgers are manually operated and the productivity mainly depends on the dredger operatorrsquo;s working experience, physical and mental status and knowledge level. So the dredger operator is difficult to keep high productivity, stable working process for long time. And on the other hand, the dredgerrsquo;s performance is totally different in diffident working conditions and by different operators. For a typical dredger, the cutting and transporting capacity need to cooperate so as to achieve higher productivity, less energy waste, long dredger service life and better environment friendliness. So first itrsquo;s necessary to optimize the cutterrsquo;s operational parameters, but little has know about the working mechanism including the slurry formation and spillage generation inside of the cutter. Some researcher designed testing experiments to explore the flow field regarding the cutter as a black box, but just measured some data on the velocity and pressure in different locations in and around the cutter. And the experiment costs long time and the measured datarsquo;s integrity, continuity and repeatability should be improved. With the rapid developing of computer-aided design and simulation, computational fluid dynamics problem can be solved by CFD software. Then for operational parameter optimization and cutter performance evaluation can be supported by constructing CFD model and simulation in CFD software.

And the purpose of this study is to simulate the flow field of the cutter and analyze the optimized operational parameters for a typical cutter and provide reasonable operation advice for dredger operation.

2 Flow Field Modeling of Cutter Head

2.1 3D Modeling of Cutter Head

The major part of cutter head for cutter suction dredger is composed of cutter hub, cutter ring, cutter arm and cutter teeth. Cutterrsquo;s designing parameters have significant influence on cutting performance and efficiency, and the important parameters are the ring diameter, speed of revolutions per minute, rated power, etc. In the research, a typical 6-arm cutter is modeled. The cutter hub and ring can be constructed by direct stretching or rotating method in CAD software referring to the 2D geometric drawing. And for the cutter arm, the mathematical reference equation method is generally used to describe its complicated space cure for its contours. To setup a cartesian coordinate system, geometrical center on the cutter ringrsquo;s upper surface is defined as the original point O, the upper surface as the plane XOY, cutter axial direction as the axis Z. The outer and inside contours can be described as below.

D is the cutterrsquo;s external diameter,

d ₁is the hubrsquo;s external diameter,

k ₁is the cutting coefficient,

k ₂is the cutterrsquo;s shape coefficient,

His the height of the cutterrsquo;s external contour peak,

theta;is the parametric variable,

Omega; ₁isthe cornerite of the external contour,

Omega; ₂the cornerite of the internal contour.

The equations for contours can be obtained by cutterrsquo;s 2D geometric drawing and some measuring results. The main parts of the cutter can be modeled in 3D CAD software as shown in Fig.

2D geometric drawing and 3D model of the cutter head

2.2 Cutter Flow Field Modeling and Analysis

Considering cutter height and ringrsquo;s diameter, a cylinder computing domain with 6000 mm diameter and 15000 mm height is setup for the cutter head, and a 220 mm diameter kidney-shape suction mouth is added according to the specific size of the studied cutter dredger. T

资料编号：[4271]