摘要: 針對(duì)液力變矩器高速旋轉(zhuǎn)產(chǎn)生較大攪油功率損失問題,以某液力變矩器為研究對(duì)象,基于CFD數(shù)值模擬及數(shù)據(jù)統(tǒng)計(jì)分析方法,提出一種攪油功率損失預(yù)測(cè)模型.該模型主要考慮液力變矩器裝配間隙幾何特征、運(yùn)行參數(shù)、潤(rùn)滑油物性與潤(rùn)滑狀態(tài)等因素影響,采用正交分解法選擇25組不同運(yùn)行參數(shù)下的攪油過程進(jìn)行數(shù)值模擬,并結(jié)合某傳動(dòng)裝置實(shí)際運(yùn)行工況和使用要求進(jìn)行了多工況驗(yàn)證.結(jié)果表明:隨著潤(rùn)滑油雷諾數(shù)增大,攪油功率損失成指數(shù)型快速增長(zhǎng);攪油功率損失隨徑向間隙的增大而減小,隨軸向間隙的增大而增大;當(dāng)徑向間隙小于9 mm時(shí),攪油損失功率隨著徑向間隙減小而急劇增大;相比于軸向間隙,徑向間隙對(duì)攪油功率損失值的影響程度更大;狹小間隙下液力變矩器攪油功率損失模型結(jié)果與數(shù)值計(jì)算結(jié)果總體符合較好,相對(duì)誤差在10%內(nèi).研究結(jié)果可為狹小間隙液力變矩器設(shè)計(jì)及綜合傳動(dòng)裝置的優(yōu)化提供一定技術(shù)支撐.
關(guān)鍵詞: 液力變矩器;攪油功率損失;狹小間隙;損失模型;數(shù)值模擬
中圖分類號(hào): S277.9;TH132.46文獻(xiàn)標(biāo)志碼: A文章編號(hào): 1674-8530(2024)11-1098-06
DOI:10.3969/j.issn.1674-8530.22.0280
呂懿晨,孫中國(guó),宮武旗,等.狹小間隙下液力變矩器攪油功率損失模型[J]. 排灌機(jī)械工程學(xué)報(bào),2024,42(11):1098-1103.
LYU Yichen, SUN Zhongguo, GONG Wuqi, et al. Churning power loss model for hydraulic torque converter with narrow surface gap[J]. Journal of drainage and irrigation machinery engineering(JDIME), 2024, 42(11): 1098-1103. (in Chinese)
Churning power loss model for hydraulic torque converter
with narrow surface gap
LYU Yichen1, SUN Zhongguo1*, GONG Wuqi1, ZOU Tiangang2, GUI Peng2
(1. School of Energy and Power Engineering, Xi′an Jiaotong University, Xi′an, Shaanxi 710049, China; 2. China North Vehicle Research Institute, Beijing 100072, China)
Abstract: To address the issue of significant power loss due to oil churning in highspeed rotation of hydraulic torque converters, this study focused on investigating a hydraulic torque converter and a predictive model for oil churning power loss based on CFD numerical simulation and data statistical analysis methods was proposed. The main parameters in the calculation model included the assembly clearance characteristics of the torque converter, the operating parameters, the physical properties and states of the lubricating oil. The proper orthogonal decomposition method was employed, and 25 groups of different operating parameters were selected, subsequently the numerical simulations for the oil stirring process were carried out for all the cases. The actual operating conditions and operating requirements of a transmission device were verified under multiple operating conditions. The results indicate that the churning power loss increases exponentially with an increase in Reynolds number of the lubricating oil, while it decreases with an increase in radial clearance and increases with an increase in axial taper. When the radial clearance is less than 9 mm, there is a sharp rise in churning power loss as the clearance decreases. Compared to axial clearance, radial clearance has a greater impact on churning power loss value. The model results for churning power loss of hydraulic torque converter under narrow clearances are generally consistent with numerical calculations, showing relative errors within 10%. These findings can provide technical support for designing hydraulic torque converters and optimizing comprehensive transmission devices.
Key words: hydraulic torque converters;churning power loss;narrow surface gaps;loss model;numerical simulation
液力機(jī)械綜合傳動(dòng)裝置是現(xiàn)代履帶車輛的主要傳動(dòng)形式之一[1],其性能很大程度上影響車輛的可靠性和動(dòng)力輸出.液力機(jī)械綜合傳動(dòng)裝置內(nèi)常裝載一定量潤(rùn)滑油,在零件表面形成潤(rùn)滑油膜,可減少摩擦損失及零件損耗,同時(shí)利用潤(rùn)滑油循環(huán)帶走零件表面因摩擦而產(chǎn)生的熱量,但也會(huì)增加傳動(dòng)部件的攪油功率損失而降低運(yùn)行效率[2].液力變矩器的殼體外部并不需要潤(rùn)滑,但為了滿足齒輪、軸承等相鄰零部件的浸油潤(rùn)滑條件,其外殼也浸入潤(rùn)滑油液中被動(dòng)攪油.因此,提出一種預(yù)測(cè)液力變矩器在狹小空間中攪油損失功率的計(jì)算方法對(duì)高性能綜合傳動(dòng)裝置設(shè)計(jì)具有重要意義.
KARMAN[3]針對(duì)無限靜態(tài)流體中盤旋轉(zhuǎn)造成的損失計(jì)算提出了經(jīng)驗(yàn)公式.SOO等[4]分析了流體浸沒旋轉(zhuǎn)圓盤的阻力矩.TEREKHOV[5]進(jìn)行齒輪攪油試驗(yàn),并基于量綱一化分析建立了單齒輪攪油損失計(jì)算公式.梁文宏等[6]通過試驗(yàn)測(cè)定了單個(gè)直齒輪的攪油功率損失,同時(shí)應(yīng)用π定理推導(dǎo)出相應(yīng)功率損失公式.WILD等[7]采用數(shù)值計(jì)算和試驗(yàn)相結(jié)合的方法研究了旋轉(zhuǎn)圓柱在封閉空間內(nèi)的能量損失.FRANCO等[8-9]使用高精度數(shù)值方法分析了幾何參數(shù)和工作參數(shù)對(duì)單個(gè)齒輪攪油功率損失的影響.趙二輝等[10]結(jié)合仿真計(jì)算及試驗(yàn)測(cè)試,研究了流體壓力對(duì)濕式離合器的摩擦影響.
旋轉(zhuǎn)件在狹小空間中的攪油功率損失計(jì)算最早可以追溯到人們對(duì)筒軸旋轉(zhuǎn)流動(dòng)的研究.COUETTE[11]利用同軸旋轉(zhuǎn)圓柱流動(dòng)的特性測(cè)量了流體的黏度.TAYLOR[12]對(duì)同軸旋轉(zhuǎn)圓柱的流動(dòng)進(jìn)行試驗(yàn)研究,發(fā)現(xiàn)隨著轉(zhuǎn)速增大,在環(huán)隙中會(huì)生成沿軸向排列的渦,即Taylor渦.MANN等[13]對(duì)圓盤攪油的試驗(yàn)研究證明,徑向間隙對(duì)攪油阻力矩的影響要比軸向間隙小.CHANGENET等[14]通過試驗(yàn)研究了單個(gè)直齒輪下徑向和軸向間隙對(duì)于攪油損失的影響,并推導(dǎo)出經(jīng)驗(yàn)公式.李超等[15]利用CFD方法研究了不同油氣比下徑向間隙對(duì)渦旋壓縮機(jī)的泄漏機(jī)理,建立了泄漏模型.
目前,針對(duì)攪油功率損失的研究,基本以齒輪攪油為主.文中以某一處于浸油狀態(tài)及狹小間隙中的液力變矩器為研究對(duì)象,基于CFD數(shù)值模擬及數(shù)據(jù)統(tǒng)計(jì)分析方法,提出一種液力變矩器攪油功率損失的預(yù)測(cè)模型,同時(shí)以某傳動(dòng)裝置內(nèi)液力變矩器的實(shí)際工況為依據(jù),對(duì)預(yù)測(cè)模型進(jìn)行驗(yàn)證.
1數(shù)值計(jì)算
1.1計(jì)算模型與網(wǎng)格劃分
采用正交分解法,選取液力變矩器25組典型運(yùn)行算例,如表1所示.表中n為轉(zhuǎn)速,T為潤(rùn)滑油溫度,h為浸油深度,jr為徑向間隙,ja為軸向間隙,μ為潤(rùn)滑油動(dòng)力黏度.
定義浸油深度h、徑向間隙jr及軸向間隙ja等特征幾何參數(shù)如圖1所示.
液力變矩器數(shù)值計(jì)算模型如圖2所示.
在圖2a中,液力變矩器周向與同軸套筒之間形成徑向間隙,端面與擋板之間形成軸向間隙.圖2b為箱體模型與圖2a中模型做布爾減運(yùn)算得到的流體域.
采用Mesh軟件對(duì)齒輪箱流體域進(jìn)行非結(jié)構(gòu)化網(wǎng)格劃分,如圖3所示.隨著25組典型算例運(yùn)行參數(shù)及幾何尺寸的變化,流體域網(wǎng)格數(shù)量在400萬~600萬內(nèi).壁面處設(shè)置邊界層網(wǎng)格,網(wǎng)格精度滿足Y+值要求.
以液力變矩器扭矩為判據(jù),選取5套網(wǎng)格數(shù)(330萬、400萬、460萬、540萬、610萬)進(jìn)行網(wǎng)格無關(guān)性驗(yàn)證.當(dāng)網(wǎng)格數(shù)為460萬時(shí),液力變矩器扭矩值與網(wǎng)格數(shù)540萬及610萬時(shí)的近似相等.因此,后續(xù)計(jì)算采用460萬網(wǎng)格數(shù).
1.2邊界條件與湍流模型
應(yīng)用計(jì)算流體動(dòng)力學(xué)軟件ANSYS-Fluent對(duì)攪油過程的非定常流動(dòng)進(jìn)行數(shù)值計(jì)算,液力變矩器旋轉(zhuǎn)運(yùn)動(dòng)采用VOF模型和滑移網(wǎng)格法.
流體域內(nèi)同時(shí)存在空氣和油兩相,設(shè)第一相為空氣,第二相為油相.計(jì)算時(shí)考慮潤(rùn)滑油重力的作用,定義y軸負(fù)方向?yàn)橹亓Ψ较?,重力加速度大小?.8 m/s2.箱體的內(nèi)壁面、擋板及套筒均設(shè)置為無滑移固定壁面.
湍流模型選取標(biāo)準(zhǔn)壁面函數(shù)的RNG k-ε模型.壓力與速度的耦合采用SIMPLE算法,對(duì)流體空間中各參數(shù)的離散,梯度項(xiàng)采用Least squares cell Based,壓力項(xiàng)采用PRESTO!.為獲得較高計(jì)算精度,計(jì)算均采用二階格式獲得最終解.
2液力變矩器攪油功率損失計(jì)算
根據(jù)表1提供的運(yùn)行參數(shù)開展25組算例的數(shù)值計(jì)算,通過數(shù)據(jù)提取和統(tǒng)計(jì),獲得相應(yīng)的液力變矩器攪油功率損失并進(jìn)行分析.
2.1計(jì)算方法與流程
液力變矩器的工況或檔位直接影響攪油流動(dòng)狀態(tài),即飛濺油滴的尺寸和時(shí)空分布等,進(jìn)而決定了攪油的損失機(jī)理類型及其功率損失大小.為描述和設(shè)計(jì)方便,通常用單一公式擬合全部檔位的攪油功率損失,但擬合精度相對(duì)較低,尤其在狹小表面間隙情況下.
文中針對(duì)狹小空間中液力變矩器的攪油功率損失,提出一種新的計(jì)算流程.首先提取基本參數(shù)(主要包括液力變矩器形狀參數(shù)、運(yùn)行參數(shù)、間隙幾何尺寸、潤(rùn)滑油物性、潤(rùn)滑狀態(tài)等),計(jì)算弗勞德數(shù)Fr和雷諾數(shù)Re,然后以雷諾數(shù)大小為依據(jù),選擇相應(yīng)流態(tài)下的模型,最后計(jì)算攪油功率損失.計(jì)算流程如圖4所示.
2.2力矩計(jì)算公式
弗勞徳數(shù)是表征流體慣性力與重力相對(duì)大小的量綱一數(shù).浸油狀態(tài)下,液力變矩器的弗勞徳數(shù)Fr為
Fr=vgh,(1)
式中:v為液力變矩器線速度.
雷諾數(shù)是表征流體慣性力與黏性力相對(duì)大小的量綱一數(shù).浸油狀態(tài)下,液力變矩器的雷諾數(shù)Re為
Re=ρωRDμ,(2)
式中:ρ為潤(rùn)滑油密度;ω為液力變矩器角速度;R為液力變矩器端面半徑; D為液力變矩器端面直徑;μ為潤(rùn)滑油動(dòng)力黏度.
液力變矩器的攪油功率損失P為
P=Mω,(3)
其中
M=ρω2R5CM,(4)
式中:M為液力變矩器攪油扭矩?fù)p失;CM為扭矩系數(shù).
當(dāng)Relt;2.0×105時(shí),
CM=10-0.874Re0.072Fr-1.947VpR3-1.118·jrR-1.111jaR1.096,(5)
當(dāng)2.0×105≤Relt;6.0×105時(shí),
CM=10-5.257Re0.541Fr0.620hR16.995·VpR311.172jrR-1.169jaR0.470,(6)
當(dāng)Re≥6.0×105時(shí),
CM=10-1.830Re0.073Fr-0.538hR-7.105·VpR35.29jrR-0.297jaR0.409,(7)
以上式中:Vp為液力變矩器浸入潤(rùn)滑油部分的體積.
2.3計(jì)算結(jié)果分析
表2為利用模型公式和數(shù)值模擬得到的液力變矩器攪油扭矩?fù)p失結(jié)果對(duì)比,表中e為相對(duì)誤差.可以看出,整體上,模型公式計(jì)算的液力變矩器攪油扭矩?fù)p失與數(shù)值模擬結(jié)果較吻合,除個(gè)別算例外,二者總體相對(duì)誤差小于10%,這表明文中所提出的狹小間隙下液力變矩器攪油功率損失計(jì)算模型是可靠的.
由于實(shí)際運(yùn)行工況比較復(fù)雜,轉(zhuǎn)速覆蓋不同雷諾數(shù)范圍,文中依據(jù)數(shù)據(jù)分析和實(shí)踐經(jīng)驗(yàn),分別針對(duì)3個(gè)雷諾數(shù)展開動(dòng)力黏度、浸油深度、徑向間隙和軸向間隙等因素對(duì)攪油損失功率的影響分析.
取動(dòng)力黏度μ=0.40 Pa·s,徑向間隙jr=20 mm,軸向間隙ja=20 mm,當(dāng)雷諾數(shù)Relt;2.0×105,轉(zhuǎn)速為50~250 rad/s,不同浸油深度(80.0,120.0,160.0,200.0,247.5 mm)時(shí),轉(zhuǎn)速對(duì)攪油功率損失的影響如圖5所示.
由圖5可以看出:整體上,攪油損失功率隨轉(zhuǎn)速增大而單調(diào)線性增大;相同轉(zhuǎn)速下,浸油深度越大,損失功率越大;損失功率隨轉(zhuǎn)速增大的速率與浸油深度具有統(tǒng)計(jì)學(xué)意義.
取動(dòng)力黏度μ=0.05 Pa·s,徑向間隙jr=20 mm,軸向間隙ja=20 mm,當(dāng)雷諾數(shù)為2.0×105~ 6.0×105,轉(zhuǎn)速為100~300 rad/s,不同浸油深度(80.0,120.0,160.0,200.0,247.5 mm)時(shí),轉(zhuǎn)速對(duì)攪油功率損失的影響如圖6所示.可以看出:攪油損失功率隨轉(zhuǎn)速增大而呈指數(shù)型增長(zhǎng);相同轉(zhuǎn)速下,浸油深度越大,損失功率越大;攪油損失功率在浸油深度較大時(shí),隨轉(zhuǎn)速增大而增大的速率越大.
取動(dòng)力黏度μ=0.01 Pa·s,徑向間隙jr=20 mm,軸向間隙ja=20 mm,當(dāng)雷諾數(shù)Regt;6.0×105,轉(zhuǎn)速為100~300 rad/s,不同浸油深度(80.0,120.0,160.0,200.0,247.5 mm)時(shí),轉(zhuǎn)速對(duì)攪油功率損失的影響如圖7所示.可以看出:此雷諾數(shù)段時(shí)轉(zhuǎn)速和浸油深度對(duì)攪油功率損失的影響與圖6較為相似,即攪油損失功率隨轉(zhuǎn)速增大呈指數(shù)性非線性增大,且隨浸油深度增大而增大,浸油深度增大還會(huì)加速攪油功率損失隨轉(zhuǎn)速增大的幅度.
為研究徑向間隙對(duì)攪油損失功率的影響,取雷諾數(shù)Re分別為1.5×105,4.0×105和8.0×105,轉(zhuǎn)速ω=200 rad/s,浸油深度h=120 mm,軸向間隙ja=20 mm,以滿足公式適用條件,按照實(shí)際條件取徑向間隙為4~20 mm,結(jié)果如圖8所示.可以看出:整體上,不同雷諾數(shù)時(shí),攪油功率損失隨徑向間隙減小均呈非線性增大趨勢(shì);當(dāng)徑向間隙小于9 mm時(shí),攪油損失隨徑向間隙的減小而急劇增大,當(dāng)雷諾數(shù)越大時(shí),攪油功率損失越?。划?dāng)徑向間隙為9~13 mm時(shí),雷諾數(shù)Re=1.5×105工況攪油功率損失最大,而雷諾數(shù)Re=4.0×105工況攪油功率損失最?。划?dāng)徑向間隙大于13 mm時(shí),雷諾數(shù)Re=8.0×105工況的攪油功率損失最大,而雷諾數(shù)Re=4.0×105工況損失最小.
3條功率損失曲線出現(xiàn)交叉,推測(cè)當(dāng)雷諾數(shù)達(dá)到一定數(shù)值時(shí),徑向間隙內(nèi)的流動(dòng)狀態(tài)發(fā)生轉(zhuǎn)變,使得損失類型和數(shù)值發(fā)生變化.
同樣地,取徑向間隙jr=20 mm,在相同的轉(zhuǎn)速、浸油深度和雷諾數(shù)下,研究軸向間隙對(duì)攪油損失功率的影響,結(jié)果如圖9所示.
由圖9可以看出:整體上,攪油功率損失隨軸向間隙增大而線性增大;雷諾數(shù)Re=8.0×105工況的功率損失相對(duì)最大,在研究范圍內(nèi)均高于另2個(gè)算例;雷諾數(shù)Re=1.5×105,4.0×105工況的攪油功率損失曲線發(fā)生交叉,軸向間隙小于11 mm時(shí),后者功率損失較大,軸向間隙大于11 mm時(shí),前者功率損失較大;軸向間隙對(duì)損失功率的影響為0~5 kW,與圖8徑向間隙攪油功率損失數(shù)值(0~25 kW)相比明顯較小.
3結(jié)論
針對(duì)液力變矩器處于浸油狀態(tài)且表面間隙狹小情況下的攪油功率損失進(jìn)行了研究,得到結(jié)論如下:
1) 基于運(yùn)行參數(shù)正交分解和典型工況計(jì)算流體動(dòng)力學(xué)數(shù)值模擬,提出了一種狹小表面間隙液力變矩器攪油功率損失的預(yù)測(cè)方法.構(gòu)建以液力變矩器結(jié)構(gòu)、運(yùn)動(dòng)參數(shù)、潤(rùn)滑油物性與潤(rùn)滑狀態(tài)等為主要影響因素,以雷諾數(shù)為基準(zhǔn)的通用攪油功率損失計(jì)算模型,對(duì)攪油狀態(tài)進(jìn)行分段評(píng)估.攪油功率損失計(jì)算模型整體相對(duì)誤差小于10%,具有較高的預(yù)測(cè)精度,可為液力變矩器優(yōu)化設(shè)計(jì)提供依據(jù).
2) 基于提出的攪油功率損失計(jì)算模型,分析了轉(zhuǎn)速、徑向間隙和軸向間隙對(duì)攪油功率損失的影響.隨著轉(zhuǎn)速或雷諾數(shù)增大,攪油功率損失呈指數(shù)型快速增大.徑向間隙較軸向間隙對(duì)攪油功率損失的影響更大.
參考文獻(xiàn)(References)
[1]毛明, 周廣明, 鄒天剛. 液力機(jī)械綜合傳動(dòng)裝置設(shè)計(jì)理論與方法[M]. 北京:兵器工業(yè)出版社, 2015: 32.
[2]PETRY-JOHNSON T T, KAHRAMAN A, ANDERSONN E, et al. An experimental investigation of spur gear efficiency[J]. Journal of mechanical design, 2008, 130(6):747-758.
[3]KARMAN V. On laminar and turbulent friction[J]. Zeitschrift fur angewandte mathematik und mechanik, 1921, 1(4):244-249.
[4]SOO S L, PRINCETON N J. Laminar flow over an enclosed rotating disk[J]. Journal of fluids engineering, 1958, 80:287-296.
[5]TEREKHOV A S. Hydraulic losses in gearboxes with oil immersion[J]. Russian engineering journal, 1975, 55(5): 7-11.
[6]梁文宏, 劉凱, 崔亞輝. 直齒輪攪油功率損失的試驗(yàn)研究[J]. 試驗(yàn)力學(xué), 2015(2):239-244.LIANG Wenhong, LIU Kai, CUI Yahui. Experimental study of power loss in spur gear churning[J]. Experimental mechanics, 2015(2):239-244. (in Chinese)
[7]WILD P M, DJILALI N, VICKERS G W. Experimental and computational assessment of windage losses in rotating machinery[J]. Journal of fluids engineering, 1996, 118:116-122.
[8]FRANCO C, TORRE A D, GORLA C, et al. A new integrated approach for the prediction of the loadindependent power losses of gears: development of a meshhandling algorithmto reduce the CFD simulation time[J]. Advances in tribology, 2016:2957151.
[9]FRANCO C, GORLA C, TORRE A D, et al. Churning power losses of ordinary gears: a new approach based on the internal fluid dynamics simulations[J]. Lubrication science, 2015, 27(5): 313-326.
[10]趙二輝, 郭闖, 汪成文, 等. 壓力對(duì)濕式離合器局部潤(rùn)滑與摩擦特性影響研究[J]. 機(jī)電工程, 2023, 40(1):8-15.
ZHAO Erhui, GUO Chuang, WANG Chengwen, et al. Influence of pressure on local lubrication and friction characteristics of wet clutch[J]. Journal of mechanical amp; electrical engineering, 2023, 40(1):8-15. (in Chinese)
[11]COUETTE M M. Etudes sur le frottement des liquides[J]. Annales de chimie et de physique, 1890, 21:433.
[12]TAYLOR G I. Stability of viscous liquid contained between two rotating cylinders[J]. Philosophical transactions of the Royal Society of London, 1923, 223:289-343.
[13]MANN R W, MARSTON C H. Friction drag on bladed disks in housings as a function of Reynolds number, axial and radial clearance, and blade aspect ratio and solidity[J]. Journal of fluids engineering, 1961, 83:719-726.
[14]CHANGENET C, VELEX P. Housing influence on churning losses in geared transmissions[J]. Journal of mechanical design, 2008, 130(6):681-688.
[15]李超, 金銀霞, 尹賀龍, 等. 渦旋壓縮機(jī)油氣混合介質(zhì)徑向間隙泄漏特性研究[J]. 流體機(jī)械, 2022, 50(8):45-51.
LI Chao, JIN Yinxia, YIN Helong,et al. Study on radial clearance leakage characteristics of oil and gas mixture medium in scroll compressor[J]. Fluid machinery, 2022, 50(8):45-51. (in Chinese)
(責(zé)任編輯陳建華)
收稿日期: 2022-11-14; 修回日期: 2023-02-09; 網(wǎng)絡(luò)出版時(shí)間: 2024-11-08
網(wǎng)絡(luò)出版地址: https://link.cnki.net/urlid/32.1814.TH.20241108.0949.014
基金項(xiàng)目: 國(guó)防科工局基礎(chǔ)研究項(xiàng)目(20195208003)
第一作者簡(jiǎn)介: 呂懿晨(1996—),男,陜西旬邑人,碩士研究生(lvyichen007@163.com),主要從事計(jì)算流體動(dòng)力學(xué)研究.
通信作者簡(jiǎn)介: 孫中國(guó)(1981—),男,湖北宜昌人,教授,博士生導(dǎo)師(sun.zg@mail.xjtu.edu.cn),主要從事流體機(jī)械數(shù)值模擬與試驗(yàn)研究.