An Analysis of the Couple Vibration Response to Fan-Air Cooled Structure in Large Thermal Power Plant

Air cooled structure is a steel-concrete vertical hybrid structure and its stiffness and mass is highly non-uniform at vertical direction.Power equipment-structural coupling vibration response is obvious.Air cooled structural dynamic property,its dynamic displacement response and dynamic strain response under different industrial conditions and different frequencies are studied by the experiment with a large-scale model and simulation calculation with ANSYS software.Results show that tested vibration mode tallies with the result of finite element analysis.Its torsion effect is significant.The vibration modes are highly coupled.Calculated model frequency is less than tested model frequency.Back-calculated archetypal structure frequency is larger than calculated archetypal structure frequency.The tested and calculated couple vibration response results are found to be in agreement with calculated results.Its low order resonance response is larger than that of high order.Fan frequency should be kept away from the first structural three frequencies.The structural dynamic displacement under the excitation of all fans can't be neglected though its dynamic strain is still within its elastic range.Great attention should be paid to fatigue failure,and it is suggested that the steel with better shock flexibility and cold-bent property and bolts with good friction and high strength should be used.