TEMPERATURE FIELD ANALYSIS TO GASOLINE ENGINE PISTON AND STRUCTURE OPTIMIZATION

Transcription

1 Journal of Teoretical and Applied Inforation Tecnoloy 0 t February 013. Vol. 48 No JATIT & LLS. All rits reserved. ISSN: E-ISSN: TEMPERATURE FIELD ANALYSIS TO GASOLINE ENGINE PISTON AND STRUCTURE OPTIMIZATION 1 HONGYUAN ZHANG, ZHAOXUN LIN, 1 JIAN XING, 1 Scool of Autoobile and Traffic, Senyan Lion University, Senyan , Liaonin, Cina General Asseble Worksop, Sanai GM (Senyan) Norso Motors Co., Ltd. (SGM-NORSOM), Senyan , Liaonin, Cina ABSTRACT Tis paper introduces te principle of teral analysis for te cobustion enine piston, ets te eat excane coefficient of te piston top and te eat excane coefficient distribution of te piston and te coolin water trou calculation, calculates te teperature field of te piston wit te finite eleent etod and odifies te calculation odel by repeatedly coparin te result wit te easured teperature. It is found out tat te teperatures of te piston top and te first circular roove are relatively i after calculatin te teperature field and based on te results te optiization scee of addin te coolin oil caber is applied to te piston structure. Results sow tat, after optiization, te axiu teperature of te piston top is decreased to 64, and te teperature at te first rin is decreased to 04, tus iprovin te workin condition of te piston rin. Keywords: Enine, piston, Teral Load, Optiization 1. INTRODUCTION As a kind of teral power acine, te workin environent for te enine is severe, as it as to bear te effect of te teral load durin operation. As te ost critical part of te enine, te workin condition of te piston can reatly influence te service life and perforance of te enine, so it is particularly iportant to carry out te teperature field analysis to te enine piston. Nowadays, te teperature field analysis work for te piston includes: Hideiko Kajiwaraa, Yukiiro Fujiokab, Tatsuya Suzukia, Hideo Neisi[1]Usin CFD tools to calculate te coefficient of eat transfer for te coolin allery, wic is influential in piston coolin. J.H. On [] usin te results of a finite eleent analysis for te prediction of te steady state teperature distribution in a i speed diesel enine piston.v. Esfaanian, A. Javaeri, M. Gaffarpour [3] calculates te eat transfer to an enine piston crown. Tree different etods for te cobustion boundary condition are used. Te results of different cobustion side boundary condition treatents are copared and teir effects on te teral beavior of te piston are investiated. H.W. Wu, C.P. Ciu[4] study presents a finite eleent eat transfer odel for te prediction of piston teperature distributions in a real tie operation enine. Te teral boundary conditions are specified adequately in te odel for various operations. Su Yao Lon, Xin Cen Kuai, Jun Cen[5] calculate Te teperature and teral stress fields for te piston of a diesel enine are usin trianular finite eleents and constant boundary eleents. Ravindra Prasad [6] proposes a nuerical etod is presented for calculatin te teperature fields in a sei-adiabatic diesel enine piston avin a coolin oil canal. Yu-Yi Wu, Bo- Ciuan Cen, Fen-Ci Hsie [7] proposes a eat transfer odel usin te Stanton nuber. Avinas Kuar Aarwal [8] Researc tie resolved nuerical odelin of oil jet coolin of a ediu duty diesel enine piston. In tis paper, we ave calculated te teperature field of te piston wit te finite eleent analysis software accordin to te basic teory of teral analysis. We ave copared te easured teperature of te piston at several key points wit te calculated results and repeatedly odified te boundary condition for te teperature and te eat excane coefficient. Fro te analysis results, we ave found out tat te teperatures of te piston top and te first circular roove zone are ier, and effectively iproved te workin condition for te piston top and te first circular roove wit te structure optiization for te piston, obtainin obvious effects, tus decreasin te teral load of te piston. 904

2 Journal of Teoretical and Applied Inforation Tecnoloy 0 t February 013. Vol. 48 No JATIT & LLS. All rits reserved. ISSN: E-ISSN: FINITE ELEMENT MODEL.1 Geoetrical Model Te finite eleent analysis to te piston is to establis te reasonable and accurate finite eleent odel first, tus carryin out analysis by arkin cell rids to obtain te accurate results finally. Accordin to te structural syetry of te piston, in order to be convenient for calculation and decrease workload, cut te establised piston odel to aintain 1/4 and ten iport te odel to te finite eleent software for te finite eleent analysis to te piston accordin to te fine interface between te odelin software and te finite eleent analysis software. Durin te iportin process, soe details ave been oitted, suc as te cafer and te snap rin of te piston pin etc. Te eoetrical odel for te piston is as sown in Fiure 1. Fiure 1: Geoetrical Model For Te Piston. Pysical Properties of te Material Table 1: Paraeters Of Te Piston Material Paraeters Piston aterial Values of te paraeters Aluinu alloy Poisson ratio 0.3 Elastic odulus of te piston Material density GPa 3 k / Conductivity factor 160 w/( K) Coefficient of teral expansion / K.3 Mes Generation Durin te es eneration for te piston odel, based on experiences and wit several trials, te eit-node exaedron cell SOLID70 is selected in tis paper. Fiure sows te final finite eleent odel after es eneration for te piston. Fiure : Mes Generation For Te Piston 3. FINITE ELEMENT ANALYSIS 3.1 Basic Teory for Teral Analysis To solve te teperature field of an object is te precondition necessary for te calculation of te teral stress, tus obtainin te teral strain and ten carryin out te accuulation wit te positive strain and searin strain of te ecanical load. Based on te basic teory for eat transission, we can deduce te differential equation of te eat transission for te object wit te internal eat source and te transient teperature field: ρ c = k q (1) V t x Were, T is te transient teperature value of te object, t is te tie, k is te conductivity factor of te aterial, ρ is te aterial density, c is te specific eat capacity of te aterial and q V is te internal eat source intensity of te aterial. Usually, k, ρ, c and q V are treated as constants, wile te stable teral analysis as notin to do wit te tie variable t, and no internal eat source as to be taken into consideration for te finite eleent analysis to te piston. So we can et = 0 () x Besides, to et te unique solution for te aforesaid differential equation, te initial condition and te boundary condition sould be added, wic are collectively called te definite condition. Ten we et couplin solution for te differential equation. In tis paper, te tird boundary condition is applied for solvin and analyzin te teperature field for te piston, wic eans tat te teperature T f and te eat excane coefficient 905

3 Journal of Teoretical and Applied Inforation Tecnoloy 0 t February 013. Vol. 48 No JATIT & LLS. All rits reserved. ISSN: E-ISSN: of te fluid ediu contactin te object is treated as te variables wose constants ave been known. We can express in te equation as follows: k = ( T Tf ) (3) n Were, n is te exterior noral vector for te object boundary, is te convection eat excane coefficient and T f is te teperature of te surroundin ediu. Te finite eleent analysis for te teperature field of te piston is to et te extree value te functional of te differential equation wit te variation principle, based on te principle of te functional of te differential equation, tus solvin te equation set wit te node teperature as te unknown variable. Based on te variation principle, te functional equation for solvin te node teperature is k I( T ) = V x ( T ρc T dxdydz t T f T ) ds (4) S Were, S is te piston boundary and V is te solution zone for te piston body. Te teperature function T ( x, y, z, t) of te piston teperature field eetin te boundary condition is obtained by carryin out variation to te aforesaid functional and obtainin te iniu solution as follows δ I = 0 (5) After discrete te piston body wit te finite eleent etod, every eleent can be considered as te sub-doain of te interal coputational e doain, tus obtainin I( T ) = I ( T ), were I e (T ) is te sub-doain for every cell. Wile te functional equation for te cells witin te sub-doain can be expressed as: e k I ( T ) = V x ( T ρc T dxdydz t Tf T ) ds (6) S Te teperature value of any point witin te cell applies te node teperature of te cell to carry out interpolation function and obtain wit calculation: T ( x, y, z, t) = N i T (7) i i Were, N i and T i are te sape function and te of te teperature cell node respectively and is te nuber of cell nodes 3. Deterination of te boundary condition 3..1 Calculation of te eat excane coefficient for te piston top Wen calculatin as a stable teperature field, it is necessary to calculate te averae teperature and te averae eat excane coefficient of te copreensive as witin a workin cycle. It is necessary to obtain te transient eat excane coefficient and te transient as teperature first, respectively. Woscni forula is based on te siilar principle and applies te cylinder diaeter D and te averae piston speed Re as te ain representation aount. Te equation for calculation is: Were, (8) = 453.6D ( CP ) T P te transient as pressure, MPa. T te transient as teperature, K ; C te piston te averae speed, / s. In order to et te averae eat excane coefficient, in te calculation of te teral load of te cobustion enine, te crank anle is pressed as te tie and a workin cycle is 70. Ten we can et = dϕ (9) Based on te coputation as stated above, = W /( K), te averae copreensive as teperature is te teperature based on as. Te expression of it wit is: T res Tus obtainin T res 1 = 0 70 T dϕ = K. (10) 3.. Heat excane coefficient between te piston and te coolin water Te eat absorbed fro te as by te piston is enerally takes up -4% of te total eat of fuel burnin. Wen te piston reaces te teral equilibriu, te eat can be (1) Transitted fro te piston rin zone and te skirt to te circulatin coolin water witin te water jacket trou te cylinder sleeve wall; 906

4 Journal of Teoretical and Applied Inforation Tecnoloy 0 t February 013. Vol. 48 No JATIT & LLS. All rits reserved. ISSN: E-ISSN: () Transitted to te fres air trou te ead of te piston durin te intake process; (3) Transitted to te oil ist and te coolin oil trou te interior caber and te oil caber of te piston. Te eat excane coefficient between te cylinder sleeve and te coolin water is = 3715W /( K). As for te initial boundary condition of te piston rin zone, please refer to Table Table : Te Boundary Condition Of Te Piston Rin Zone Location Sybol Heat excane coefficient Piston junk Top ede of te first 456 circular roove Inner ede of te first 375 circular roove 3 Botto ede of te first 331 circular roove 4 Top ede of te second 389 circular roove 5 Inner ede of te second 44 circular roove 6 Botto ede of te second 389 circular roove 7 Top ede of te tird 387 circular roove 8 Inner ede of te tird 44 circular roove 9 Botto ede of te tird 387 circular roove 10 Botto rin land of te 145 first rin 11 Botto rin land of te 145 second rin 1 Te piston skirt Boundary condition for te piston teperature field calculation Fro te eat excane coefficient calculation for eac part of te aforesaid piston, we can et tat te boundary condition for te eat excane coefficient calculation for eac part, tus ettin te piston teperature field calculation. In soe parts, te oriinal coputational doain is subdivided accordin to te coputation results, increased or decreased based on te different positions, tus eetin te actual condition better. Wen deterinin te boundary condition, in order to et te analyzed results ore close to te actual operation condition of te piston. based on te structure features and key parts, te piston 13 surface can be divided into 18 boundary zones wit te position of eac part as sown in Fiure 3. Fiure 3: Dividin Diara For Te Teral Boundary Zone Of Te Piston Wit te coparison to te experiental results and repeated coputation adjustent of te experiental results, te eat excane coefficient and te teperature of te piston boundary are as sown in Table 3. Table 3: Heat Excane Coefficient And Teperature Of Te Piston Location Heat excane coefficient Abient teperature Coputation and Result Analysis of te Teperature Field Based on te establised eoetrical odel and finite eleent odel as well as te establised boundary condition and wit te stable teral analysis odule of te finite eleent analysis software, we can calculate and et results as sown in Fiures 4&5. 907

5 Journal of Teoretical and Applied Inforation Tecnoloy 0 t February 013. Vol. 48 No JATIT & LLS. All rits reserved. ISSN: E-ISSN: Fiure 4: External Surface Teperature Field Of Te Piston Fiure 5: Teperature Field Of Te Inner Caber Of Te Piston Fro Fiures 4&5, we can et: (1) Te piston teperature canes between and wit te axiu teperature at te piston top and te iniu teperature at te lower part of te piston skirt. () At te piston rin land, teperatures are distributed uniforly alon te piston in te radial direction. We can see clearly tat te teperature of te piston skirt is alon te piston pin ole is ier tan tat perpendicular to te pin ole, tus causin te teral deforation of te piston in te direction of te piston pin is reater. (3) Te piston teperature canes uniforly fro te piston top to te botto, witout any sarp cane penoenon. Te piston axiu teperature is at te piston top surface wit te teperature of about 80 and te teperature of te upper surface of te first circular roove bein about 30. However, te allowable averae teperature of te first circular roove of te aluinu piston is 180 to 0 and te teperature of te first circular roove is ier. (4) Te isoteral line of te circular roove zone is ticker tan tat of te skirt, indicatin tat te teperature of te circular roove zone of te piston canes reatly, so te teral stress is relatively concentrated, causin it easy to be daaed. To assess te teral condition of te piston, we sould first pay attention to te axiu teperature of te piston top and te teperature of te first circular roove, te allowable averae teperature of te aluinu piston top is 300 to 350 and te allowable averae teperature of te first circular roove is 180 to 0. Tis standard indicates tat except te teperature of te first circular roove, te overall teperature of tis piston is witin te allowable averae teperature, but te teral load is severe. In i teperature, te aterial intensity will decrease and te i-teperature creep will occur. In te uneven teperature field, te piston in operation will cause reat teral stress, wic will easily cause te piston cracked after lon-tie operation. Te over-i teperature of te first circular roove will not only decrease te intensity of soe aterials of te circular roove, speed up te circular roove wearin, and influence te aseous rin titness, but also easily cause te piston rin ceented. So, it is necessary to take easures to carry out optiization desin for te piston, so as to decrease te teral load of te piston. 4. STRUCTURE OPTIMIZATION ANALYSIS OF THE PISTON 4.1 Te Model after Optiization Fro te teperature field analysis, we can et tat te axiu teperature of te piston is below 80, so no special aterials are needed, but aluinu alloy will be acceptable. Te teperature of te first piston rin is i, wic can easily cause carbonization of lubricatin oil, tus leadin to te ceentation of te piston rin wic will cause te rin to lose obility. So tis can be te key point for optiization. We sould apply te etod of addin te coolin oil caber to decrease te teperature of te first circular roove. Te odel after te structure optiization is as sown in Fiure 6. Fiure 6: Te Tree-Diensional Model Of Te Piston After Optiization 908

6 Journal of Teoretical and Applied Inforation Tecnoloy 0 t February 013. Vol. 48 No JATIT & LLS. All rits reserved. ISSN: E-ISSN: Coparison of te Teperature Fields before and after te Structure Optiization Wit te boundary condition wic is te sae as tat used for te stable teral analysis before optiization, te eat excane coefficient of te coolin oil caber of 1300 W /( K) and te abient teperature of 130, te analysis result is as sown in Fiures 7&8. piston rin, so te overall optiization result is satisfactory. 5. CONCLUSION Result of te finite eleent analysis of te piston sows tat, te axiu teperature of te piston before optiization is 80 wic occurs at te piston top, te teperature of te first circular roove is about 30,and tat of te first circular roove is relatively i so it needs to be optiized. Wit te optiization scee of addin te coolin oil caber, te axiu teperature te piston is decreased by 16 and te overall averae teperature of te first circular roove is decreased to 04, wic confors to te allowable averae teperature of te piston. So te optiization scee is effective. Fiure 7: Te Teperature Field Of Te External Surface Of Te Piston After Optiization Fiure 8: Te Teperature Field Of Te Inner Caber Of Te Piston After Optiization Coparin te result in Fiure 4 wit tat in Fiure 5, we can et tat te axiu teperature of te piston top after addin te coolin oil caber is decreased to 64, wic is 16 lower tan te axiu teperature of te oriinal odel of 80. It as also been effectively relieved tat te teperature of te piston skirt alon te piston pin ole is ier tan tat perpendicular to te pin ole, tus decreasin te teral deforation of te piston in te direction of te piston pin. Fro te fiure, we can et tat te axiu teperature of te first circular roove of te piston is 19 but te overall averae teperature is about 04, tus effectively iprovin te workin condition of te first rin. Te teral load of te circular roove zone decreases and te teral stress will also decrease accordinly, tus extendin te service life of te REFERENCES: [1] Hideiko Kajiwara, Yukiiro Fujioka, Tatsuya Suzuki, Hideo Neisi, An analytical approac for prediction of piston teperature distribution in diesel enines, JSAE Review, Vol. 3, No. 4, 00, pp [] J.H, On.Steady state teral analysis of a diesel enine piston, Coputers in Industry, Vol. 15, No. 3, 1990, pp [3] V. Esfaanian, A. Javaeri, M. Gaffarpour, Teral analysis of an SI enine piston usin different cobustion boundary condition treatents, Applied Teral Enineerin, Vol. 6, No. -3, 006, pp [4] H.W. Wu, C.P. Ciu, Finite eleent odel for teral syste in real tie operation diesel piston, Coputers & Structures, Vol. 3, No. 5, 1989, pp [5] Su Yao Lon, Xin Cen Kuai, Jun Cen, Boundary eleent analysis for axisyetric eat conduction and teral stress in steady state, Enineerin Analysis wit Boundary Eleents, Vol. 1, No. 4, 1993, pp [6] Ravindra Prasad, Investiation of eat transfer in an oil cooled piston wit and witout ceraic insulation on crown face, International Journal of Mecanical Sciences, Vol. 31, No. 10, 1989, pp [7] Yu-Yi Wu,Bo-Ciuan Cen, Fen-Ci Hsie, Heat transfer odel for sall-scale aircooled spark-inition four-stroke enines, International Journal of Heat and Mass Transfer, Vol. 49, No. 1-, 006, pp

7 Journal of Teoretical and Applied Inforation Tecnoloy 0 t February 013. Vol. 48 No JATIT & LLS. All rits reserved. ISSN: E-ISSN: [8] Avinas Kuar Aarwal, Tie resolved nuerical odelin of oil jet coolin of a ediu duty diesel enine piston, International Counications in Heat and Mass Transfer, Vol. 38, No. 8, 011, pp [9] M. Spaniel, J. Macek, M. Divis, R. Ticanek, Diesel enine ead steady state analysis, International Journal of Middle European Construction and Desin of Cars, Vol., No. 3, 003, pp [10] R. Ticanek, M. Spaniel, M. Divis, Steady state eat analysis of enine ead, International Journal of Szécenyi István University of Applied Sciences, Vol. 0, No. 3, 003, pp