绞吸式挖泥船吸泥机刀盘流场分析外文翻译资料

 2021-12-20 21:32:03

绞吸式挖泥船吸泥机刀盘流场分析

简介

对于绞吸式挖泥船,探索泥浆形成机制对提高挖泥船的效率和性能起着重要作用。为了优化挖泥船的工作参数,本研究中对绞吸式挖泥船的刀头进行了流场模拟。首先,根据设计的2D几何图和相关的经验轮廓曲线,在收集必要的参数后,通过3D建模软件构建绞刀的3D模型。然后将模型导入CFD进行分析,在不同的工作条件下对刀具的流场进行数值模拟,以实现刀头内和周围的速度和压力分布。并且基于仿真结果,可以在设备使用寿命,环境保护和能耗方面找到优化的工作点。

1介绍

绞吸式挖泥船因其广泛的深度范围,良好的土壤适应性和高工作效率而在世界范围内得到越来越广泛的应用,并且可以连续完成疏浚,卸料和泥浆处理过程一次。吸嘴周围的泥浆形成与几个因素有关,包括土壤性质,挖泥船的结构和操作参数。结构参数是刀具的类型,吸嘴的形状和位置等。可操作的由切割器转速,摆动速度和泵转速等组成。

由于切割器的旋转和搅拌,将沙子或土壤切碎并与水混合成浆液。沙子将被压碎成不同大小的颗粒,一些大直径将沉淀到水流底部,小尺寸的颗粒将流入水中。因此,进入水中的沙子的体积与沙子的破碎程度有关。根据吸力,浆料将部分或完全吸入吸嘴。颗粒的运动可简化为螺旋运动,用于通过旋转刀头引起的离心力和由于泵的吸力而接近吸嘴的向前运动的扩散运动的组合。

大多数挖泥船都是手动操作的,生产率主要取决于挖泥船操作员的工作经验,身体和精神状态以及知识水平。因此,挖泥船操作员很难长时间保持高生产率,稳定的工作过程。而另一方面,挖泥船的性能在不同的工作条件和不同的操作员之间完全不同。对于典型的挖泥船,切割和运输能力需要配合,以实现更高的生产率,更少的能源浪费,更长的挖泥船使用寿命和更好的环境友好性。因此,首先必须优化切割机的操作参数,但很少了解工作机制,包括切割器内部的浆料形成和溢出。一些研究人员设计了测试实验来探索关于刀具的流场作为黑盒子,但只是测量了刀具内和周围不同位置的速度和压力的一些数据。并且实验需要很长时间,并且应该改进测量数据的完整性,连续性和可重复性。随着计算机辅助设计和仿真的快速发展,CFD软件可以解决计算流体动力学问题。然后通过在CFD软件中构建CFD模型和仿真来支持操作参数优化和刀具性能评估。应改善连续性和可重复性。随着计算机辅助设计和仿真的快速发展,CFD软件可以解决计算流体动力学问题。然后通过在CFD软件中构建CFD模型和仿真来支持操作参数优化和刀具性能评估。应改善连续性和可重复性。随着计算机辅助设计和仿真的快速发展,CFD软件可以解决计算流体动力学问题。然后通过在CFD软件中构建CFD模型和仿真来支持操作参数优化和刀具性能评估。

本研究的目的是模拟刀具的流场,分析典型刀具的优化运行参数,为挖泥船运行提供合理的操作建议。

2刀头流场建模

2.1刀头的三维建模

绞吸式挖泥船刀头的主要部分由刀盘,刀环,刀臂和刀齿组成。刀具的设计参数对切削性能和效率有显着影响,重要的参数是环直径,每分钟转速,额定功率等。在研究中,典型的6臂铣刀进行了建模。切割轮毂和环可以通过CAD软件中的直接拉伸或旋转方法来构造,参考2D几何图形。对于刀臂,通常使用数学参考方程方法来描述其轮廓的复杂空间固化。为了设置笛卡尔坐标系,刀具环上表面的几何中心定义为原点O,上表面定义为平面XOY,刀具轴方向定义为轴Z. 外轮廓和内轮廓可以描述如下等式。

(2)

d是刀具的外径,

d1是轮毂的外径,

k1是切割系数,

k2是刀具的形状系数,

H是刀具外部轮廓峰值的高度,

theta;是参数变量,

Omega;1外部轮廓的角落,

Omega;2内部轮廓的角落。

轮廓方程可以通过刀具的2D几何图形和一些测量结果获得。刀具的主要部件可以在3D CAD软件中建模,如图1所示。

图。1。

刀具的2D几何图形和3D模型

2.2刀具流场建模与分析

考虑到刀具高度和环的直径,为刀头设置了直径为6000 mm,高度为15000 mm的圆柱计算域,并根据所研究的绞刀的具体尺寸添加了直径为220 mm的肾形吸嘴。然后将构建的3D切割器模型划分为Fluent预处理器Gambit中的网格。平衡计算机硬件性能和计算精度和时间,刀具的流场分为刀具水域,刀具近水域和刀具远程水域,三个水域由自适应混合四面体非结构化网格。最后将刀具水域划分为795142个网格,将近水场切割成475567个网格,并将刀具远程水域分成434160个网格。

由于刀头内部的浆料流场复杂,并且速度总是在变化,因此在用CFD求解流场时通常认为是湍流。较为成熟两方程的k-ε模型通常用于模拟紊流[ 45 ]。在分析了几个模型之后,选择标准k-ε方程来关闭控制方程。湍流动能方程式为方程式。(3)湍流扩散方程为方程。(4)。

Ccedil;1ɛ,Ccedil;2ɛ,Ccedil;3ɛ是等式的常数项的系数,

Gk,Gb 分别是浮力产生的速度梯度和湍流动能,

小号ķ,小号ɛ 是用户定义的函数,

yuml;中号是脉动扩张的波动,

mu;是湍流粘度系数。

控制方程由最常用的有限体积方法离散化,并通过欧拉模式求解。在CFD过程中,采用残值来判断计算结果的收敛性为作为精度。

疏浚水面通过一个标准大气压连接到大气,因此切割深度压力可以转换为标准大气压,这构成了切割机流场中压力进入的边界条件。作为连续过程,流体流入计算域并在计算域的出口外流动,因此条目的边界条件与退出的边界条件匹配。根据实际工程经验,出口速度设定为4.6 m / s。在疏浚过程中,流场非常复杂,内部泥浆流动不稳定。为了方便计算,所有水域都被认为是静止的,刀具工作区域被处理为旋转,刀具加工过程简化为稳定流动。可以参考实际疏浚参数来设置每个计算域的初始条件。近水区和远水区的流体介质可选用Fluent中建立和选配的水液,其值可设定为一个标准大气压。对于切割水区域中的流体介质,可以选择水或浆料,并且可以选择2种标记有mud1和mud2的浆料,如表1所示,用于模拟。

表格1。

流体介质参数

密度(kg / m 3)

动态粘度(kg / ms)

水的液体

998.2

0.001

泥1

1200

0.0032

泥2

1400

0.009

3不同参数对刀具流场的影响分析

当绞吸式挖泥船工作时,切割机中的浆料密度随着疏浚参数而变化。基于CFD理论,流场中的浆料被视为均匀流动。通过改变疏浚参数并分析其对切割机流场的影响,可以实现经济运行参数。在研究中,如表2所示,具有2个浆料密度和6个切割器旋转速度的浆料,与实际疏浚工程类似,被选择用于分析。并且每个密度和每个转速可以被命名为一个工作条件(WC)。

表2。

模拟工作条件

RPM

12 r / m

18 r / m

24 r / m

30 r / m

36 r / m

42 r / m

密度

1200公斤/米3

WC1

WC2

WC3

WC4

WC5

WC6

1400公斤/米3

WC7

WC8

WC9

WC10

WC11

WC12

为了比较不同浆料密度和刀具转速下刀具流场的压力分布图和速度矢量图,定位了4个位置的压力和速度,这些位置标有1#,2#,3#,4# ,是刀臂与刀环上表面,臂内,吸嘴入口和排液流线之间的连接。目标位置如图2所示 。

刀具流场中的4个目标位置

3.1浆料密度对刀具流场的影响分析

浆料密度设定为1200 kg / m 3和1400 kg / m 3,在不同的刀具转速下数值模拟刀具流场,然后在Fluent中实现压力分布图和速度矢量图,并且压力值可以达到如表34中所列,也可以实现目标1#和2#。由于本文的计算结果太多无法展示,其中部分选择如图3所示。

表3。

1#,2#的压力,浆料密度为1200 kg / m 3

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

1#

27.45

59.31

97.86

160.77

229.21

306.36

2#

13.77

30.38

50.5

81.38

115.87

145.79

表4。

1#,2#的压力,浆料密度为1400 kg / m 3

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]

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