Research On Flow Characteristic Of The Flameproof Diesel Engine Exhaust System

Flameproof diesel engine, as one of underground vehicle powers, is applied more and more widely. Its advantages contain high thermal efficiency, low fuel consumption, as well as safety use, flexible operation and so on. Washing tank and outlet flame trap, which are installed on the exhaust system, increase the resistance of exhaust system, and induce to bad ventilation process and combustion process, weak dynamic property and fuel economy. This paper mainly engages in reducing exhaust resistance and decreasing pressure loss, and it has great significance for improving the whole performance of flameproof diesel engine.Taking flameproof diesel engine exhaust system as the research object, this paper uses fluid dynamics analysis software FLUENT to simulate and analyze fluid flow characteristics. The research goal is to reduce the resistance of flameproof diesel engine exhaust system. The main research contents are shown as follows:1) With the use of FLUENT software, it is easy to simulate gas flow in exhaust manifold, exhaust pipe and exhaust manifold-exhaust pipe, and get the distributions of flow field velocity in the exhaust system. The results show that strong eddy currents in two side positions disappear in the improved exhaust gas model, and flow resistances decrease. Furthermore, to some extent, it improves exhaust performance of flameproof diesel engine exhaust.2) With the help of UG software, three dimensional models of exhaust manifold wall, inner gas, and inner cooling water are established separately, then, these models are assembled together. This paper also divides mesh by using GAMBIT software, and simulates fluid flow, heat transfer, and coupled heat transfer between exhaust manifold and fluid by using FLUENT software. So, inner flow field distribution and temperature field distribution can be concluded. The results show that the surface temperature of original water-jacket exhaust manifold and improved model does not reach423k, and it meets the need of explosion-proof request.3) The model of gas-liquid two-phase flow in washing tank is established. Then, this paper conducts the numerical simulation and contrast analysis for three kinds of models, including primitive washing tank, single smoke board washing tank and double smoke board washing tank. So, the distributions of inner pressure, velocity and gas phase volume fraction are mainly studied. The results show that, in smoke board washing tank, the contact surfaces between cooling water and gas increases, and its cooling effect is better.4) Three dimensional models of original square tube outlet flame trap and improved square tube outlet flame trap are established by using UG software. Then, with the applying of FLUENT software, the distributions of pressure, velocity, turbulent kinetic energy are analyzed in comparison. The results show that improved square cube outlet flame trap can reduce the intensity of swirl, decrease gas loss, enhance stability of flow field, and improve exhaust performance of outlet flame trap in flameproof diesel engine.