Research On Urban Air Convection Mechanis Based On Vortex Engine Theory

This paper attempts to use the vortex engine theory to alleviate the problem of excessive temperature in the central area of the city and the difficulty of spreading the concentration of pollutants.A narrow scale geometric model is established,experiments and numerical calculations are carried out to verify the feasibility of the vortex engine system in urban buildings.For the optimal design of the stability and strength of the enhanced vortex flow field,the main conclusions are as follows:?1?Through experiments and numerical calculations on the reduced geometric model,and comparing the obtained results,through the experimental phenomena and the measurement of various parameters,it shows that the design in this paper successfully forms the vortex flow field,and the numerical calculation results.Compared with the experimental results,the error is kept within 10%,which indicates that the numerical calculation results can show the actual situation of the flow field more comprehensively.?2?The diameter of the exit of the vortex flow field stabilization zone will affect the strength and stability of the vortex flow field.When the ratio of the inlet diameter of the vortex stabilization zone to the height of the vortex generator is 0.75,the vortex intensity is the largest,and The mass flow at the exit is large,the pressure in the central region of the vortex flow field is low,and the vortex flow field has the best effect.When the diameter of the inlet of the vortex flow field is too small,the vortex flow field cannot be formed.During the process of increasing,the vortex gradually increases.After reaching a certain value,the influence of the increase of the diameter on the vortex flow field decreases.?3?According to the influence of inlet temperature on the vortex flow field,the results show that the temperature at the inlet determines the formation of the vortex flow field and the strength and stability of the vortex flow field under certain conditions.Increasing the temperature can enhance the strength and stability of the vortex flow field.The optimal inlet temperature in this paper is 1200K.?4?Under the different inclined angles of the baffle placement,when the inclination angle is large,the average speed of the bottom of the vortex generator is larger and the distribution is more uniform.Therefore,it is considered that the inclination angle of the baffle placement can be appropriately increased,so that the vortex can occur.The internal velocity of the device is large and the distribution is relatively uniform.The numerical calculation and comparison results for the geometric model in this paper show that the average velocity distribution inside the vortex generator is more uniform when the inclination angle is 25°.?5?Try to keep the slit between the buildings as small as possible,which can improve the strength and stability of the vortex flow field.When the slit width is 50mm,the vortex intensity at the exit of the vortex flow field stabilization region is the maximum value of14.593,and the negative pressure at the center of the vortex flow field is lower at this time,and the mass flow at the outlet of the vortex flow field stabilization region is higher.Large,so this paper believes that for this geometric model,when the slit width between buildings is 50mm,a relatively more stable and stronger vortex flow field can be obtained.?6?Using the similarity theory to calculate the parameters in the urban building complex,the results are as follows:the temperature difference between the heat source and the external environment required to form the vortex flow field in the urban building group is approximately 7.7×10^-2?,and the air throughput for the urban center reaches:At10839t/h,which means that the vortex engine system is built in the urban building complex,which has feasibility and application value.