| Air-powered engine is the kind of power plants that generate output work through the expansion of high-pressure. In these days of increasingly serious problems of energy security and environment protection, it possesses many advantages which, when compared with existing internal combustion engines, primarily due to its "zero pollution, zero fuel consumption" that can be widely applied in vehicles and power generators and has great prospects for the commercial market. The designs of valve train of recent air-powered engines in studies at home and abroad generally follow the ones of the internal combustion engine, which use rotation of camshaft to achieve the engine inlet and exhaust; or use high energy gas blowing impeller to generate work, and do not give full play to the unique characteristics of high-pressure air-powered engine, and the structure and efficiency are less ideal. The object of this study– the piston-exhausting air-powered engine, which adopts the inlet and exhaust system of cylinder-top inlet and piston-exhausting, possesses better structural simplicity and maneuverability than existing air-powered engines, and, with the unidirectional gas flow, the flow resistance of exhaust can be reduced. In order to further enhance the efficiency of piston-exhausting air-powered engine and establish a reusable, extensible and flexible platform for its design and performance simulation, based on the analysis of working principles and processes of piston-exhausting air-powered engine and the structural optimization of exhaust piston, the mathematical model of the engine is established in this paper, and with this basis the performance simulation platform is implemented. With this platform the performance indices of influence factors of the proposed piston-exhausting air-powered engine are analyzed, including:1) Adopt FLUENT as simulation platform for the analysis of the flow field in the piston exhaust flow channel. Use the flow status of velocity and pressure distribution vectors from results of simulation to predict the flow channel design property, the streamlined channel design is selected according to analysis of the piston exhaust;2) Adopt ANSYS as the analysis platform for the finite element analysis of entire exhaust piston. According to finite element theory, take Pistons 1 / 2 model as an analysis object, select the state of maximum force acting on the piston to perform the static mechanical analysis, use stress field obtained from simulation which includes stress and deformation of the stress distribution to predict the high risk regional and maximum deformation region, according to analysis the vent diameter can be increased to 35mm, the friction with the cylinder wall can be reduced by rounding the bottom of the piston;3) Establish the mathematical model in accordance with the engine working principle and process. A fixed step size fourth-order Runge - Kutta solution method is used in this model, in the MATLAB / GUIDE environment, the performance simulation platform is implemented under the modular design. With this platform the engine performance and impact factor are analyzed to obtain useful conclusions. |
