Research On Dynamic Responses Of Fan Bridge Truss Of Many Air Cooling Fans In Operation

At present, air cooling system is widely used in large thermal power plant in north China. There are many advantages of large air cooling system, such as saving water and energy, less equipment, simple system, flexibe adjustment in the amount of air, freezing good performance and so on. Fan bridge truss is an important part of air cooling system and supports the structure of fan system. Currently, there is a few of study on effect of many air cooling fans in operation on dynamic response of fan bridge truss. The main reason is air cooling system made up by many fan systems and the dynamic response of fan bridge truss is very complicated when fans are running simultaneously. So it is very important to research on dynamic response response of fan bridge truss for designing reference.Four fans and their supporting structures are selected from air cooling system, and uses structural analysis software ANSYS, establish the finite element modal of the structure, analyse the free vibration of the fan system. This paper select 15 kinds of the combinations of running of fans and exert oscillation forces of 1:1 modle of fan system on the middle of fan bridge truss, choose the vibration response of displancement of a certain fan truss center as a reference, research the effect of many air cooling fans in operation on dynamic response of fan bridge truss.Because of some causal factors such as construction and installation and so on, the quality gravity of designed center of fan rotor and the geometric center of fan system don't overlap, mass eccentricity of fan rotor has been produced. The difference phase angles may exist among oscillation forces in different air cooling fan systems. This paper input difference phase angles of oscillation force on the middle of fan bridge truss, when calculation effect of many air cooling fans in operation on dynamic response of fan bridge truss. Comparing the result of maximum displacement value of the dynamic response of fan bridge truss which are exerted by difference phase angles of oscillation force and the zero phase angles of oscillation force, the most unfavorable combinations of running of fans and the relationship of phase angle of fan blades can be defined.