en سیستم های ذخیره ساز انرژی Storage systems (battery, ultracapacitor, flywheel, etc) پژوهشي Research Use of natural gas has been proposed as one of the solutions to reduce fossil fuel consumption such as petrol and gasoline, which emit more pollutants. In this regard, more attention has been directed toward use of natural gas due to its high calorific value and low pollution. This paper studies the effect of different fluid rotation coefficients in parallel form with a surface of a piston bowl (Swirl). And, it attempts to explore the changing effects of this indicator on power and major pollutants of sparking ignition gas engines. Three-dimensional computational fluid dynamics are employed to simulate the procedure. Open-cycle engine, the moment between air-intake-valve opens and the exhaust-valve opens, is simulated through applying combustion equations of turbulence and emissions. First, the results are validated based on experimental data. Then, an analysis of different rotation coefficients is used to compare the temperature and pressure inside the cylinder, productivity, and the amount of generated pollution. The results demonstrate that changing the shape of entrance port, which leads to concomitant change in the fluid rotation rate in the chamber, causes a slight change in the output power. But, the change has a significant impact on the production of pollutants. gas engine, output power, pollution, rotation coefficient, air entrance port 3167 3177 http://ase.iust.ac.ir/browse.php?a_code=A-10-370-1&slc_lang=en&sid=1 Yasin Babajanpour yasin_babajanpour@yahoo.com 180031947532846003572 180031947532846003572 Yes Sama technical and vocational training college, Islamic Azad University, Babol Branch, Babol, Iran Davood Domiri Ganji ddg_davood@yahoo.com 180031947532846003573 180031947532846003573 No Mechanical Engineering Department, Babol Noshirvani University of Technology, P.O. Box 484, Babol ,Iran Saber Gholipour sgh6889@gmail.com 180031947532846003574 180031947532846003574 No Department of Mechanical Engineering, Sari Branch, Islamic Azad University, Sari, Iran