吳興亞,高霄鵬
海軍工程大學(xué)艦船工程系,湖北武漢430033
全回轉(zhuǎn)雙槳船舶操縱性預(yù)報(bào)
吳興亞,高霄鵬
海軍工程大學(xué)艦船工程系,湖北武漢430033
為實(shí)現(xiàn)對(duì)全回轉(zhuǎn)槳船操縱性的預(yù)報(bào),根據(jù)船舶分離型運(yùn)動(dòng)模型的建模方法,考慮全回轉(zhuǎn)槳在水平面上周轉(zhuǎn)的靈活性與受力的特殊性,著重分析雙槳受力,建立適用于全回轉(zhuǎn)對(duì)轉(zhuǎn)槳船模的MMG操縱運(yùn)動(dòng)數(shù)學(xué)模型;模擬船模進(jìn)行PMM運(yùn)動(dòng),求得水動(dòng)力導(dǎo)數(shù)并采用四階龍格—庫塔法對(duì)操縱性常微分方程進(jìn)行求解;對(duì)某工程船在靜水中的回轉(zhuǎn)運(yùn)動(dòng)和Z形操縱運(yùn)動(dòng)進(jìn)行數(shù)值仿真預(yù)報(bào),并將預(yù)報(bào)結(jié)果與自航模操縱性試驗(yàn)結(jié)果進(jìn)行對(duì)比。結(jié)果表明,兩者吻合度較高,驗(yàn)證了針對(duì)全回轉(zhuǎn)對(duì)轉(zhuǎn)槳船模所建立的船舶運(yùn)動(dòng)數(shù)學(xué)模型的有效性,可為全回轉(zhuǎn)槳船的操縱性預(yù)報(bào)提供一種較為可靠且行之有效的方法。
全回轉(zhuǎn)槳;MMG數(shù)學(xué)模型;水動(dòng)力導(dǎo)數(shù);數(shù)值仿真;操縱性預(yù)報(bào)
船舶操縱性作為船舶性能研究的重點(diǎn),始終是影響船舶安全航行的重要因素之一。目前,通常有3種基本方法預(yù)報(bào)船舶的操縱性,即基于特征參數(shù)的回歸公式或數(shù)據(jù)庫的方法、自由自航模試驗(yàn)方法以及基于數(shù)學(xué)模型的數(shù)值計(jì)算方法。沈定安和王化明等[1-2]利用數(shù)值計(jì)算方法,分別對(duì)波浪中的船舶以及雙槳雙舵船舶進(jìn)行了操縱性預(yù)報(bào);盧曉平、姚迪等[3-5]則對(duì)三體船的操縱特性進(jìn)行了仿真計(jì)算研究。而全回轉(zhuǎn)推進(jìn)器作為一種相對(duì)新型的動(dòng)力推進(jìn)裝置,可以繞軸線做360°的回轉(zhuǎn),在任何方向均可獲得最大推力,它可以使船舶原地回轉(zhuǎn)、橫向移動(dòng)、急速后退和在微速范圍內(nèi)進(jìn)行操舵等特殊駕駛操作。目前,針對(duì)裝備這一新型推進(jìn)裝置船舶的操縱性預(yù)報(bào)較少。王培生[6]、褚德英等[7-8]及劉百順等[9]重點(diǎn)研究了全回轉(zhuǎn)推進(jìn)器的發(fā)展趨向并對(duì)其水動(dòng)力性能做了研究預(yù)報(bào);Kim等[10]和Abramowicz-gerigk[11]針對(duì)大型集裝箱船和雙槳雙舵客輪,通過建立數(shù)學(xué)模型進(jìn)行了數(shù)值模擬;康偉等[12]則對(duì)可回轉(zhuǎn)雙槳電力推進(jìn)船舶的運(yùn)動(dòng)模型進(jìn)行了研究。
本文將通過理論仿真預(yù)報(bào)與模型試驗(yàn)相結(jié)合的方法,針對(duì)某一民用全回轉(zhuǎn)對(duì)轉(zhuǎn)槳船模,通過數(shù)學(xué)建模、船槳受力分析、水動(dòng)力導(dǎo)數(shù)求取以及方程求解等工作對(duì)其操縱性運(yùn)動(dòng)進(jìn)行仿真預(yù)報(bào),繼而獲得適用于全回轉(zhuǎn)對(duì)轉(zhuǎn)槳船舶的運(yùn)動(dòng)數(shù)學(xué)模型,為全回轉(zhuǎn)槳船模的操縱性快速預(yù)報(bào)提供一種行之有效的方法,為今后綜合評(píng)估裝備有這一新型推進(jìn)器船舶的操縱特性,掌握其操縱運(yùn)動(dòng)的規(guī)律,改進(jìn)其操縱性能提供方法上的借鑒思路。
1.1 坐標(biāo)系
如圖1所示,本文采用2個(gè)右手直角坐標(biāo)系建立MMG船舶操縱運(yùn)動(dòng)方程,一個(gè)固定在地球上,為固定坐標(biāo)系O-x0y0z0,另一個(gè)固定在船體上,為運(yùn)動(dòng)坐標(biāo)系G-xyz(G為坐標(biāo)原點(diǎn),與船舶質(zhì)心重合)。在計(jì)算船舶水動(dòng)力導(dǎo)數(shù)時(shí),采用如圖1所示的運(yùn)動(dòng)坐標(biāo)系,在計(jì)算船舶仿真運(yùn)動(dòng)軌跡時(shí),則采用固定坐標(biāo)系。
圖1 船舶運(yùn)動(dòng)坐標(biāo)系Fig.1 Motion coordinate systems of the ship
1.2 MMG數(shù)學(xué)模型
假定該船模航行在無限深廣水域,船體視作剛體,自由液面作為靜水面;僅考慮船舶在水平面內(nèi)運(yùn)動(dòng),忽略船舶橫搖上的影響,根據(jù)MMG方程的研究方法[8],船舶在水平面上的MMG操縱運(yùn)動(dòng)方程為:
式中:m為船舶質(zhì)量;mx和my分別為船舶在x軸和y軸方向上的附加質(zhì)量;Iz和Jz分別為船體繞z軸的轉(zhuǎn)動(dòng)慣量和附加質(zhì)量轉(zhuǎn)動(dòng)慣量;u和v分別為船舶的縱向速度和橫向速度;r為船體繞z軸的轉(zhuǎn)動(dòng)角速度;u?,v?,r?分別為對(duì)縱向速度、橫向速度和轉(zhuǎn)動(dòng)角速度求導(dǎo)所得加速度;XH,YH和NH分別為除推進(jìn)器外的所有外力作用在船體上的縱向力、側(cè)向力和艏搖力矩;XP,YP和NP分別為螺旋槳作用在船體上的推力、橫移力和艏搖力矩。
1.3 附加質(zhì)量
mx,my,Iz和Jz采用以下回歸公式進(jìn)行計(jì)算。
式中:CB為方形系數(shù);d為設(shè)計(jì)吃水;B為型寬;L為設(shè)計(jì)水線長。
1.4 船體水動(dòng)力
當(dāng)船舶的運(yùn)動(dòng)參數(shù)為微小量時(shí),常常略去高階項(xiàng),故作用在船體上的力和力矩可簡化為:
式中:X0為直航阻力;Xu,Yv,Yr,Nv,Nr為相應(yīng)水動(dòng)力系數(shù)。
1.5 全回轉(zhuǎn)槳水動(dòng)力
本文的研究對(duì)象為全回轉(zhuǎn)對(duì)轉(zhuǎn)槳雙槳船舶,其結(jié)構(gòu)圖如圖2所示。在進(jìn)行槳水動(dòng)力計(jì)算時(shí),分別用L和R表示左、右螺旋槳,螺旋槳模型如圖3所示,主要幾何參數(shù)如表1所示。左右螺旋槳對(duì)稱分布,與船舶質(zhì)心G的距離為xG,與船舶縱向中心線的距離為y。
圖2 全回轉(zhuǎn)雙槳船示意圖Fig.2 Schematic of full-revolving propeller ship
圖3 槳模型Fig.3 Model of propellers
表1 螺旋槳主要幾何參數(shù)Table 1 The main geometric parameters of propellers
以左槳為例,單槳在靜水中產(chǎn)生的軸向推力為TL,當(dāng)螺旋槳在水平方向上產(chǎn)生一個(gè)回轉(zhuǎn)角φ時(shí),螺旋槳推力在運(yùn)動(dòng)坐標(biāo)系x軸、y軸產(chǎn)生的投影分量分別為XL,YL,對(duì)船體產(chǎn)生的轉(zhuǎn)船力矩為NL。各力和力矩公式如下:
其中:k為左(右)槳推力系數(shù);ρ為水密度;n為螺旋槳轉(zhuǎn)速;D1為前槳的槳盤面直徑;t為左(右)槳在x軸方向上的常規(guī)推力減額系數(shù);p為左(右)槳對(duì)船舶y軸方向側(cè)向力的影響系數(shù);q為左(右)槳對(duì)船舶z軸方向艏搖力矩的影響系數(shù);φ為左(右)槳在水平方向上旋轉(zhuǎn)的角度。
同時(shí),對(duì)于此類全回轉(zhuǎn)雙槳式吊艙槳,前槳與后槳、槳與吊艙以及裝配在船后時(shí)與船之間存在相互干擾,使得其水動(dòng)力性能變得尤為復(fù)雜。在確定左右槳推力系數(shù)時(shí),在敞水下選取不同偏轉(zhuǎn)攻角,分別為0°,±15°和±30°,取不同進(jìn)速系數(shù),得出不同攻角、不同進(jìn)速系數(shù)J下前后槳的推力系數(shù),本文計(jì)算時(shí)進(jìn)速系數(shù)公式為
式中,Vm為螺旋槳進(jìn)速,由該公式確定的進(jìn)速系數(shù)可得到本文所用螺旋槳的推力系數(shù)。
由于左右螺旋槳結(jié)構(gòu)、材質(zhì)相同,對(duì)稱安裝,正常工作時(shí)轉(zhuǎn)速始終保持相同且旋轉(zhuǎn)角度在水平面內(nèi)始終為同一方向,所以當(dāng)兩槳同時(shí)工作時(shí),對(duì)船體產(chǎn)生的水動(dòng)力為:
在求解針對(duì)本船模的MMG操縱運(yùn)動(dòng)方程中的水動(dòng)力導(dǎo)數(shù)時(shí),基于STAR-CCM+軟件平臺(tái),采用RANS方程和流體體積(Volume of Fluid,VOF)算法,針對(duì)某一工程船船模(圖4)進(jìn)行PMM運(yùn)動(dòng)數(shù)值仿真模擬,考慮自由液面的興波與航行過程中船模姿態(tài)的變化,建立了船模按斜航運(yùn)動(dòng)、純橫蕩運(yùn)動(dòng)以及不同振蕩模式下艏搖運(yùn)動(dòng)3種工況下的操縱性水動(dòng)力導(dǎo)數(shù)求解方法,并將仿真求解結(jié)果與利用回歸公式的求解結(jié)果相印證,得出全回轉(zhuǎn)對(duì)轉(zhuǎn)槳船模的水動(dòng)力導(dǎo)數(shù),其求解結(jié)果見表2。
3.1 仿真船模要素
數(shù)值仿真計(jì)算船模為一民用工程船模,船模無量綱化主要參數(shù)如表3所示。
圖4 水動(dòng)力導(dǎo)數(shù)計(jì)算船模及網(wǎng)格劃分Fig.4 Calculation model of hydrodynamic derivatives and meshing
表2 水動(dòng)力導(dǎo)數(shù)計(jì)算結(jié)果Table 2 The results of hydrodynamic derivatives
表3 船模無量綱化主要參數(shù)Table 3 Main dimensionless parameters of the model
3.2 仿真實(shí)驗(yàn)
針對(duì)已經(jīng)建立起來的適合全回轉(zhuǎn)雙槳船模的MMG操縱運(yùn)動(dòng)方程,水動(dòng)力導(dǎo)數(shù)借助STAR-CCM+軟件平臺(tái)模擬船舶斜航、純橫蕩和純艏搖3種運(yùn)動(dòng)工況計(jì)算求出,繼而通過求解時(shí)域微分方程即可實(shí)現(xiàn)對(duì)船舶操縱運(yùn)動(dòng)動(dòng)態(tài)特征的計(jì)算機(jī)模擬仿真,得出船模特定的運(yùn)動(dòng)軌跡以及時(shí)域特性。本文借助MATLAB計(jì)算軟件平臺(tái),在不考慮船舶橫搖、縱傾對(duì)船模的影響下,采用四階龍格—庫塔法對(duì)操縱性常微分方程進(jìn)行求解,得到特定航速不同舵角下目標(biāo)船模的回轉(zhuǎn)運(yùn)動(dòng)軌跡以及做回轉(zhuǎn)運(yùn)動(dòng)的定常回轉(zhuǎn)直徑等特征參數(shù)。
在船模航速4.3 kn下,數(shù)值仿真計(jì)算了±5°,±10°,±15°,±20°,±25°,±30°和±35°操舵角下的回轉(zhuǎn)運(yùn)動(dòng)以及±10°和±20°時(shí)的Z形操縱試驗(yàn),左右螺旋槳在計(jì)算過程中保持轉(zhuǎn)速不變且做完全相同的運(yùn)動(dòng)。
3.3 數(shù)值仿真預(yù)報(bào)與自航模試驗(yàn)結(jié)果
數(shù)值仿真預(yù)報(bào)與自航模試驗(yàn)結(jié)果如圖5~圖8所示。定?;剞D(zhuǎn)和Z形操縱的預(yù)報(bào)結(jié)果如表4~表5所示。
圖5 4.3 kn,15°舵角回轉(zhuǎn)運(yùn)動(dòng)時(shí)的無因次軌跡仿真和試驗(yàn)曲線Fig.5 The dimensionless simulation and trial curves of rotating motion in 4.3 kn,15°rudder angle
圖6 4.3 kn,10°舵角回轉(zhuǎn)運(yùn)動(dòng)時(shí)的無因次軌跡仿真和試驗(yàn)曲線Fig.6 The dimensionless simulation and trial curves of rotating motion in 4.3 kn,10°rudder angle
圖7 4.3 kn,10°/10°Z形操縱試驗(yàn)曲線Fig.7 The trial curve of zigzag test in 4.3 kn,10°/10°rudder angle
圖8 4.3 kn,20°/20°Z形操縱試驗(yàn)曲線Fig.8 The trial curve of zigzag test in 4.3 kn,20°/20°rudder angle
表4 航速4.3 kn下定?;剞D(zhuǎn)預(yù)報(bào)結(jié)果Table 4 The prediction results of constant turning at 4.3 kn
表5 航速4.3 kn下Z形操縱預(yù)報(bào)結(jié)果Table 5 The prediction results of zigzag test at 4.3 kn
3.4 結(jié)果分析
以全回轉(zhuǎn)雙槳船模為計(jì)算模型,數(shù)值模擬船模的PMM運(yùn)動(dòng),基于3種不同運(yùn)動(dòng)工況求得船舶操縱的各線性水動(dòng)力導(dǎo)數(shù),并與通過回歸方程的計(jì)算結(jié)果進(jìn)行比對(duì),驗(yàn)證了數(shù)值仿真的有效性。
在船模的回轉(zhuǎn)運(yùn)動(dòng)仿真預(yù)報(bào)中,特定航速不同舵角下的各回轉(zhuǎn)運(yùn)動(dòng)軌跡、定?;剞D(zhuǎn)直徑以及回轉(zhuǎn)戰(zhàn)術(shù)直徑等操縱性參數(shù)與自航模試驗(yàn)數(shù)據(jù)結(jié)果吻合較好,均在船舶操縱性標(biāo)準(zhǔn)規(guī)定的波動(dòng)范圍內(nèi)。
在Z形操縱試驗(yàn)仿真預(yù)報(bào)中,超越角、初轉(zhuǎn)期以及表征船舶操縱性能的各個(gè)指數(shù),其仿真預(yù)報(bào)值與模型試驗(yàn)結(jié)果相吻合,符合艦船通用規(guī)范的要求。
考慮到全回轉(zhuǎn)槳受力的復(fù)雜性以及初次探索該型船操縱性預(yù)報(bào)方法,本文針對(duì)全回轉(zhuǎn)槳船舶建立的數(shù)學(xué)模型僅考慮了線性部分,在接下來的工作中將考慮進(jìn)一步完善。
本文圍繞全回轉(zhuǎn)對(duì)轉(zhuǎn)雙槳船舶的操縱性展開仿真計(jì)算研究,在建立針對(duì)此船型的數(shù)學(xué)模型、數(shù)值計(jì)算出該目標(biāo)船型的水動(dòng)力導(dǎo)數(shù)的基礎(chǔ)之上,對(duì)全回轉(zhuǎn)槳船舶的回轉(zhuǎn)運(yùn)動(dòng)軌跡、Z形操縱試驗(yàn)軌跡進(jìn)行了數(shù)值仿真,根據(jù)仿真預(yù)報(bào)結(jié)果與船舶湖試試驗(yàn)數(shù)據(jù)的對(duì)比分析,得出如下結(jié)論:
1)本文提出了一種針對(duì)全回轉(zhuǎn)槳船舶的操縱性預(yù)報(bào)方法,并將仿真預(yù)報(bào)的回轉(zhuǎn)試驗(yàn)、Z形操縱結(jié)果與自航模試驗(yàn)結(jié)果進(jìn)行了對(duì)比,驗(yàn)證了本文針對(duì)全回轉(zhuǎn)對(duì)轉(zhuǎn)雙槳建立的船舶運(yùn)動(dòng)數(shù)學(xué)模型的有效性與適用性;
2)通過將數(shù)值仿真計(jì)算與回歸公式結(jié)果進(jìn)行比對(duì),驗(yàn)證了本文采用的水動(dòng)力導(dǎo)數(shù)計(jì)算方法與計(jì)算結(jié)果的準(zhǔn)確性,為求解所建立的船舶運(yùn)動(dòng)數(shù)學(xué)模型奠定了基礎(chǔ);
3)本文對(duì)于全回轉(zhuǎn)對(duì)轉(zhuǎn)槳船舶操縱性的準(zhǔn)確預(yù)報(bào)具有一定的工程實(shí)用價(jià)值,可為今后全回轉(zhuǎn)槳船舶的操縱性快速預(yù)報(bào)提供技術(shù)支撐與依據(jù)。
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Maneuverability prediction for a ship with full-revolving twin propellers
WU Xingya,GAO Xiaopeng
Department of Naval Architecture Engineering,Naval University of Engineering,Wuhan 430033,China
To predict the maneuverability of full-revolving propeller ships,this paper analyzes the propeller force and establishes MMG equations for controlling motion mathematical models that are suited to the full-revolving propeller model,in accordance with the modeling method of the separating ship motion model and taking into account the special nature of the force and flexibility of a full rotation in the horizontal plane of a full-revolving propeller.Secondly,hydrodynamic force derivatives for the ship model are obtained by simulating the model's PMM movement,and the controlling Ordinary Differential Equation (ODE)is solved using the four-stage Rung-Kuta method.Finally,the numerical simulation of a certain ship's rotating motion and its zigzag test in still water is obtained,and the prediction results are compared with that of a self-running model.It is found that the simulation results agree well with the trial results,and the effectiveness of the ship motion model for the full-revolving propeller model is validated.In brief,this paper provides a reliable and effective method of predicting the maneuverability of full-revolving propeller ships.
full-revolving propeller;MMG mathematical model;hydrodynamic derivatives;numerical simulation;maneuverability prediction
U661.33
A
10.3969/j.issn.1673-3185.2017.01.005
2016-06-06
2016-12-28 15:59
吳興亞(通信作者),男,1992年生,碩士生。研究方向:艦船流體動(dòng)力性能。E-mail:282294867@qq.com高霄鵬,女,1971年生,博士,副教授。研究方向:艦船流體動(dòng)力性能
http://www.cnki.net/kcms/detail/42.1755.TJ.20161228.1559.032.html期刊網(wǎng)址:www.ship-research.com
吳興亞,高霄鵬.全回轉(zhuǎn)雙槳船舶操縱性預(yù)報(bào)[J].中國艦船研究,2017,12(1):27-31,62. WU X Y,GAO X P.Maneuverability prediction for a ship with full-revolving twin propellers[J].Chinese Journal of Ship Research,2017,12(1):27-31,62.