Effects of Different Deviations of Helical Inlet Port on Performance

2012 ◽  
Vol 516-517 ◽  
pp. 888-891 ◽  
Author(s):  
Xue Dong Zhang ◽  
Ping Sun ◽  
Wen Xia Lu ◽  
Li Hua Ye
Keyword(s):  
Numerical Simulation ◽  
Diesel Engine ◽  
Flow Characteristics ◽  
Inlet Port ◽  
Axial Deviation ◽  
Solid Models

In this paper, the helical inlet port of CZ4B26 diesel engine is studied. Its3-D solid models of port with the axial deviation and rotated port are made to research the effect on helical inlet port performance. Based on the validation of CFD precision by test, the numerical simulation of flow characteristics in ports-valve-cylinder system is carried out. The results showed that the axial deviation of the port and rotated port have a range of effects on the performance of inlet port.

A Numerical Simulation of Fuel Premixing for PCCI Combustion by Direct Injection

2011 ◽  
Author(s):  
Tsuyoshi Kondo ◽  
Tsuguhiko Nakagawa
Keyword(s):  
Numerical Simulation ◽  
Diesel Engine ◽  
Direct Injection ◽  
Vertical Direction ◽  
General Purpose ◽  
Injection Timing ◽  
Injection Angle ◽  
Equivalent Ratio ◽  
Local Equivalent ◽  
The Rich

Diesel engine has some advantages that thermal efficiency is high and control response is fast. On the other hand, more particulate matter (PM) and nitrogen oxide (NOx) are contained in the exhaust gas of diesel engine. Premixed charge compression ignition (PCCI) combustion is proposed to reduce the PM and NOx. In the lean range of equivalent ratio, unburned fuel is left and in the rich range, PM and soot are generated. For the practical use of PCCI combustion, mixing fuel and air well is important under the low equivalent ratio of injection. In this study, the mixing characteristics of fuel and air in a cylinder were numerically evaluated. A numerical simulation was performed with general-purpose simulator. The fuel has been injected into the vertical direction of cylinder and injection angle has been defined as 0 degree. In order to express the collusion, impingement on the wall model, that defines behavior of a droplet impinged on the wall with the Weber number of a droplet, was applied. By the injection timing, standard deviation of local equivalent ratio at Top Dead Center (TDC) was plotted. In this study, Frequency of mixing in each cell statistically was observed to evaluate the fuel-air mixing degree. The authors have taken notice of the condition which can be reduced the amount of scatter in the distribution of local equivalent ratio.

Numerical Simulation Study on the Recovery Process of Autonomous Underwater Vehicle

2021 ◽  
Author(s):  
Weigang Huang ◽  
Donglei Zhang ◽  
Jiawei Yu ◽  
Tao He ◽  
Xianzhou Wang
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Autonomous Underwater Vehicle ◽  
Flow Characteristics ◽  
Recovery Process ◽  
Underwater Vehicle ◽  
Hydrodynamic Performance ◽  
Time Step ◽  
Convergence Test ◽  
Motion Paths

Abstract AUV (Autonomous Underwater Vehicle) recovery is considerably influenced by the nearby flow field and simulations of AUV in different motion paths in the wake of a submarine with a propeller are presented in this paper. A commercial CFD solver STAR CCM+ has been used to research the motion and flow characteristics of AUV, which using the advanced computational continuum mechanics algorithms. The DARPA (Defense Advanced Research Projects Agency) SUBOFF Submarine (L1 = 4.356m) propelled with INSEAN (Italian Ship Model Basin) E1619 propeller is used in this study, and the self-propulsion characteristics of the propeller at an incoming flow velocity of 2.75m/s are obtained through numerical simulation and results are compared with the available experimental data to prove the accuracy of the chosen investigation methodology. A grid/time-step convergence test is performed for verification study. AUV (L2 = 0.4356m) is a smaller-scale SUBOFF without a sail, which approaches the submarine in different motion paths in the submarine wake at a relative speed combined with the dynamic overlapping grid technology. The hydrodynamic performance of the AUV when approaching the submarine and the velocity distribution of the surrounding flow field are analyzed, which provides a useful reference for underwater recovery of the AUV.

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