| Light rail is,a kind of modern vehicle transportation,which is convenient and fast.People's demand for the car environment is also increasing when they enjoy the convenience of travel.Comfortable inside environment of vehicles relies not only on the stable performance of supply air duct system but also on reasonable layout of air inlet to achieve ideal indoor air distribution,which bears close relation with the air quality,airflow velocity,temperature and humidity inside the compartment.Narrow space and varying passenger capacity at different time of a day could result in great difference on the inside environment of vehicles.Therefore,studies on the uniformity of supply air,rationality of airflow distribution and relationship between the change of passenger capacity and supply air parameters have important theoretical value and practical significance in ensuring the comfort of vehicle environment as well as conserving resources and reducing consumption.The study of this thesis takes a mid-carriage of certain light rail as research object,established 3-D models of the hydrostatic air duct and typical passenger capacity and performed simulation analysis of the airflow field inside light rail by applying CFD numerical simulation method.Numerical simulation analysis of static pressure air duct was initially introduced in this thesis to analyze the influence of internal structure factors on the uniformity of supply air and the static pressure plate angles inside the static pressure cavity.Meanwhile,the thesis adopted a measure which was to add baffle plate and wind deflector to solve the problem of low supply air velocity on the sides of air outlet.After that,a simulation analysis was given to indoor airflow field of full-load in summer.The result showed the distribution of indoor airflow was not uniform.By analysis of different schemes on air inlet layout and hydrostatic plate angle which affected airflow distribution,the thesis proposed an optimized structure solution features layout of air inlet asymmetric with the air outlet in distribution and varied angles of diffuser.Based on the optimized structure,the influence of solar radiation on the airflow inside the compartment was analyzed,which showed that the optimized structure can reduce the average temperature in the passenger area from 23.953? to 23.115? and effectively improve the utilization of refrigerating output.At the same time,relative humidity increased from 47.27% to 50.37% with the decrease of average wind speed from 0.434m/s to 0.300m/s,which met the average wind speed requirement for compartment(below 0.35m/s).Finally,the thesis analyzed the relationship between passenger capacity and supply air parameters.By simulating the temperature field characteristics of compartment under 4 typical passenger capacity circumstances,the result showed that due to the variation of daily passenger capacity,the waste rate of refrigerating output was about 15.44% when the air conditioner was in the constant temperature output mode.Therefore,changing temperature output of air-conditioner according to different passenger capacity conditions can not only improve the comfort level of passengers but also reduce the electricity consumption and save energy.The study of this thesis demonstrated practical value in providing references for the design of air diffuser blade angle,optimizing indoor airflow distribution of light rail compartment and adjusting supply air parameters according to different passenger capacity conditions. |
PDF Full Text Request