38 1 010 () Journal of Fuzhou University(Natural Science) Vol. 38 No. 1 Feb. 010 : 1000-43 (010) 01-0080 - 06 FLUENT,, (, 350108) : (CFD), Fluent,,.,,,.,,,., CFD,,,. : FLUENT; ; ; ; : TK4 : A Num er ica l sim ula tion of the flow f ield in d iesel eng ine exhaust man ifold ba sed on FL UENT HUANG J ian, L IN Xiao - hui, YAN Shi - rong (College ofm echanical Engineering and Automation, Fuzhou University, Fuzhou, Fujian 350108, China) Abstract: A computational fluid dynam ics( CFD ) model was constructed for exhaust manifold of diesel engine. W ith the software of FLUENT the air - flow through it was analyzed. The design quality of m anifold could be evaluated by means of calculating the degree of distribution and circulation of the flow field. According to the results of calculation, the inlet and outlet m ass flow were evenness and air flow s were basically smoothly, no visible turbulence was found, but there were still some areas that showed higher dynam ic p ressure. m anifold was imp roved. In order to reduce the energy lost, the mechanical structure of the The numerical sim ulating study indicated that both flow ability and dynam ic p ressure were significantly imp roved. CFD technology has been app lied to study how the mechanical structure of the manifold would affect its internal flow field and help find a way to imp rove the perform ance of the engine including op tim ization of manifold structure and help reduce the resistance of the in ternal air flow and enhancem ent of the exhausting efficiency. Keywords: FLUENT; diesel engine; exhaust manifold; flow field; numerical simulation 1,,. [ 1 ],,,,,.,,,,,., CFD (Cmputational Fluid Dynam ics),,,,. : 009-03 - 31 : (1965 - ),,, E - mail: huangjian 0 @ yahoo. com. cn
1, : FLUENT 81 CA4113Z,,,,.,,. [ ] : :, 9 9t (<) + div (u<) = div ( < grad<) + S < (1) t, u, <, <, < S <,, 1., u i i, E,. k - RNG, () (3) [ 3-4 ],. 5 ( k) + 5 5t 5 ( ) 5t + 5 u j k - eff 5k k u - eff j - = k t ( c 1 P + c 3 P B ) - = t ( P + P B ) - - 5 1 Tab. 1Equa tion s of correspond ing var iable < < S < 1 0 0 5p u i - + S i E - pdiv( u) + < + S i 3 5u i t - c k + c 4 5u i 3 5u i t + k 5u i : k,, t,, P = 5u i ( 5u i + 5u j ), P B = - + k 5u i () - C 3 (1 - / 0 ) 1 + 3 k (3) eff, eff =+ t, PP B g i 5, g i i,, = S k, S. RNG k - Tab. Table of RNG k -m odel coeff ic ien t c c 1 c c 3 c 4 k 0 0. 085 1. 4 1. 68 0-0. 387 0. 719 0. 719 4. 38 0. 01 CFD [ 5 ].,,,,,. PRO /E,, Fluent Gambit,. 1. Tet/ Hybrid, Tgrid.,, 47 188,,. 136 54 10-6 m, 6. 77 917 10-5 m,. 179 03 10-9 m 3, 1. 761 898 10-7 m 3. 1 Fig. 1Grid of flow field
8 () 38, 3,,,, 0. 3 MPa, 1 000 K, 0. 11 MPa, 700 K,,,,,,. Fluent,. 3 Tab. 3The property of sm oke /kgm - 3 C p /Jkg - 1 K - 1 /W m - 1 K - 1 /kgm - 1 s - 1 0. 354 1 46 0. 085 1 4. 14e - 05 3 3. 1,,. 5,,,,.,,,, 4 5,. Fig. Contours of dynam ic p ressure when cylinder 1 exhaust 3 Fig. 3Path lines when cylinder 1 exhaust 4 ( ) Fig. 4Velocity vectors ( intersection of tube ) 5 ( ) Fig. 5Velocity vectors ( intersection of tube 3) 3.,.,,,, 8 9.
1, : FLUENT 83 6 Fig. 6Contours of dynam ic p ressure when cylinder exhaust 7 Fig. 7Path lines when cylinder exhaust 8 ( ) Fig. 8Velocity vectors ( intersection of tube 1) 9 ( ) Fig. 9Velocity vectors ( intersection of tube 3) 3. 3,,,,.,,,. 4, CA4113Z,,,,,,,.,,,,,,, 10,, Fig. 10Model of flow field after imp rovement. 10.,, 11 1,, 13 14.
84 () 38 11 Fig. 11Comparison the intersection of outlet before and after imp rovement when cylinder 1 exhaust 1 Fig. 1Comparison the intersection of outlet before and after imp rovement when cylinder exhaust 13 Fig. 13H istogram of velocities when cylinder 1 exhaust 14 Fig. 14H istogram of velocities when cylinder exhaust
1, : FLUENT 85 4,,,,, 9. 45%9. 44%1. 89% 1. 88%. : - = 4 Tab. 4The in let and outlet ma ss flow when each tube exhaust q m1 /kgs - 1 q m /kgs - 1 q m3 /kgs - 1 q m4 /kgs - 1 /% 0. 74 337 9 0. 368 767 38 0. 368 758 47 0. 74 097 89 9. 45 0. 74 343 07 0. 368 748 64 0. 368 756 65 0. 74 098 04 9. 44 5. 155 80e - 06 1. 874 566e - 05 1. 817 94e - 06 1. 490 116e - 07 / 0. 403 998 0. 50 806 31 0. 50 00 6 0. 403 6 7 1. 89 0. 403 949 71 0. 50 75 07 0. 501 986 3 0. 403 605 1. 88 4. 848 838e - 05 5. 44 03e - 05 3. 47 67e - 05 1. 749 396e - 05 / 5 1) [ 6 ],,,,. ),,. 3),,,. : [ 1 ],,,. [ J ]., 00, 0 (5) : 44-48. [ ],,,. Fluent[M ]. :, 007: 33-35. [ 3 ]. [D ]. :, 003. [ 4 ],,,. FLUENT - [M ]. :, 004. [ 5 ],. [ J ]., 006, 8 (4) : 5-7. [ 6 ] Ugur Kesgin. Study on the design of inlet and exhaust system of a stationary internal combustion engine[ J ]. Energy Conversion and Management, 005 (46) : 58-87. ( : )