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Optimization Research on a Nature Gas Engine Compression Ratio Guodong Feng1, Ying Gao, Jun Li，Yan Qin State Key Laboratory of Automotive Simulation and Control, Jilin University, Changchun, China 1838135048@qq.com Keywords: Compression Ratio, Nature Gas Engine, Combustion chamber Abstract: The CNG engine in this paper is developed based on a prototype diesel engine platform.
We designed three different models with different compression ratio for the simulation and the analysis in the condition that other parameters being equal.
Table.1 The engine operating conditions Parameters Speed Pressure Temperature Equivalent ratio Mixture gas Density Value 1400r/min 140KPa 420K 0.67 1.2Kg/m3 As the cylinder calculation in the CFD-WM module of the fire is transient calculation.
The analysis and optimization of the simulation results In the combustion process, the temperature, pressure, flame surface density and the turbulent kinetic energy directly reflect the combustion state under different compression ratio.

Golovitchev .CFD-Based Optimization of a Diesel-fueled Free Piston Engine Prototype for Conventional and HCCI Combustion[C].SAE 2008-01-2423 [3] Mao J, Zuo Z, Li W, et al.
Multi-dimensional scavenging analysis of a free-piston linear alternator based on numerical simulation[J].
Numerical simulation of a spark ignited two-stroke free-piston engine generator [J].
Simulation of a two-stroke free-piston engine for electrical power generation [J].

This environment monitoring system can be extended to other fields of fire control training simulations, and it has a broad application prospect.
Using a CFD Simulation in Designing a Smoke Management System in a Building[C].
Proceedings of the 2006 Winter Simulation Conference, Dec, 2006:2071-2076 [2] Sheng'an Duan, Kaitao Cheng, Quanbo Ge, Chenglin Wen.

Introduction To reduce environmental degradation of Urban Heat Island, many researches regarding to outdoor environment are carried out, such as field measurement, simulation and wind tunnel test.
Yoshida Shinji, Murakami Shuzo and Mochida Akashi et al. developed a new method for predicting the human comfort in outdoor thermal space with the aid of CFD (Computational Fluid Dynamics), integrated with convection, radiation and moisture transport [4].
The ground material is considered to influence the outdoor thermal environment, however, most of the research on the ground material focused on simulation and few constant observation data is published.
Influence of Green Area Ratio on Outdoor Thermal Environment with Coupled Simulation of Convection, Radiation and Moisture Transport.

Structure Optimization and Numerical Verification of Plenum Chamber for Relaxation Heat Setting Machine Shuquan Song1, 2, a , Youhua Ge 1, b and Haitao Zhao1, c 1College of Mechanical Engineering, Yancheng Institute of Technology, Yancheng 224051, China 2College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics & Astronautics, Nanjing, 210016, China asq_song@126.com, bcngeyh@126.com, czhaotaohai@sina.com  Keywords: structure optimization, flow distribution, numerical simulation, opening ratio.
Based on experiments, Zhang et al suggest that the air flux which flowing through orifice plate is closely related to opening ratio, unreasonable opening ratio will lead to uneven airflow distribution upon the fiber [2].Zhang et al study the impingement freezer with different opening ratio by numerical simulation method, and think 5% is the optimum rate [3].
Table 1 Structure parameters of the plenum chamber Opening ratio β(%) 10 Working width of machine Wg (m) 1.2 Maximum width of machine Wmax (m) 2.0 Height of air inlet Hin (m) 0.2 Minimum aspect ratio of plenum chamber imin 3 Length of setting machine LD (m) 2.0 Table2 Results of optimization design β1 (%) β2 (%) β3 (%) β4 (%) β5 (%) W (m) H (m) 16.5 10.2 8.4 7.7 7.3 1.727 0.386 Numerical Validations of Optimization Results The simulation of the flow field is conducted with the commercial CFD code FLUENT, which applies a finite-volume method for the solution of conservation equations for mass, momentum and energy of a continuous fluid.
The numerical simulation results indicate that reduce opening ratio along the width and select optimization dimension is an effective method, it can results in the relative velocity error rate decrease by 23.7%.
China Synthetic Fiber Industry.Vol.33 (2010), p.55 [3] Z.Zhang, J.XIE: Numerical Simulation on flow and temperature Fields in quick freezer with perforated plates.

In 2008, Wang Yang et al set up a simulation model of water-jet guided laser cutting silicon wafer, stainless steel and 65Mn, the simulation results revealed that the effect of water jet cooling on temperature field is very distinct and the silicon wafer had the least heat affected zone of all [4].
All the above several literatures treated the simulation of water–jet guided laser processing almost based on the thermal action of laser and convective heat transfer of water jet.
The parameters related to the simulation were listed in Table 1.
Parameters employed in the simulation Parameter Type Pulse energy [J] Pulse width [ms] Jet diameter [mm] Jet speed [m/s] Material type Material diameter [mm] Thickness [mm] Setting 0.1 0.5 0.13 100 Stainless steel disc 0.3 0.1 Before these operations, using computational fluid dynamic (CFD) software to get the impact curves of water jet, which included wall pressure and shear, but the forces were variable with the geometric shape of water jet and closely related to the moving erosion front between water jet and workpiece.
The simulation model was established with two-dimensional axisymmetric mode.

Simulation Results and Discussions The Development of CI Engine Model.
Simulation Results.
Comparison of Simulation Results for Different Equivalence Ratios.
The simulation results show good agreement between with the measured data.
Oztop, Mujdat Firat, Ahmet Koca, CFD modeling of heat transfer and fluid flow inside a pent-roof type combustion, International Communications in Heat and Mass Transfer. (2010)

Fire simulation on buildings with accommodation inside the factory (hazard): use fire simulation to analyze the effective evacuation time with residential fire alarms.
Chen, A study of Hazard Rescue Simulation for Steel Frame Building at Residential and Commercial Mixed Area-Examle of Fukano Bakery Fire in Changhua County, DaYeh University, (2017)
Smokeview, A Tool for Visualizing Fire Dynamics Simulation Data Volume I: User's Guide, NIST Sp.
Jang, CFD Simulation and Assessment of Life Safety in a Subway Train Fire, Tunnel.

This work consists in performing a three-dimensional numerical simulation of a two-phase Hydrogen-Water flow inside a horizontal cylindrical channel.
Modeling and numerical simulation are used as solutions to problems encountered in different industries [1-15].
The simulation was performed unsteady for several seconds, with a time step of 0.01 seconds.
Modélisation et simulation numérique d’écoulements diphasiques pour la microfluidique.
Thomas, Advances in computational fluid dynamics (CFD) of 3-dimensional gas-liquid multiphase flows, ANSYS Germany GmbH, Otterfing, Germany, (2005)

A multi-propose commercial CFD software, FLUENT 6.3, has been employed in solving the governing equations for continuity, momentum, and energy for the numerical simulations of flow and temperature fields.
All the simulations used the structured computational mesh and the total number of cells is approximately 21,000.
The advection of moving fiber is included in the present simulations and the temperature of glass fiber is also the part of numerical solutions.
This flow pattern is in fact similar to the results by Yoo and Jaluria [10] in their isothermal flow simulations which used constant resin viscosity and did not include any thermal effects.
Jaluria, “Simulation of the flow in a coating applicator for optical fiber manufacture,” Comput.