Axial Fan Blade Failure

7 8 stressing of axial impellers 7 8 1 introduction.

Axial fan blade failure.

The forced draft fan is an axial flow fan horizontally in front of the boiler and the fan is single stage. The depth and length of the cracks and the rapid increase in vibration from the fan speed apparently from the fan blade flexing at the crack s during rotation led to the conclusion that at least one blade was on the way to catastrophic failure. Causes of inadequate airflow to the fan include a backwards installed or running impeller improper blade angle setting missing cut off an impeller not centred with inlet collars slow fan speed dirty or clogged inlet improper running clearance or improper inlet cone to wheel fit. The forced draft fan fdf blade in a 300 mw coal fired power plant that experienced catastrophic failure has been investigated.

This paper includes the affects on the performance of axial fan due to the failure of different parts. Visual inspection metallographic analysis chemical composition and hardness test were carried out to find the cause of the failure. There were two main locations of the blade damage namely damage at. The flow is axial at entry and exit.

Both blades were replaced with care to maintain the balance of the entire assembly and then. Fan performance is wrong. Flow induced vibrations and failure of axial fan blades in electric generators axial ventilation by use of axial fans was the most common cooling concept for hydropower generators in sweden during the 50 70 s when the main part of the swedish hydropower plants where built. Wtw bill cory in fans and ventilation 2005.

The fdf blade has been run for 5 years and before its failure the fdf experienced high vibration 14 mm s. As in most cases the blades are cantilevered and only supported at the end adjacent to the hub fluctuating stresses are more important. E authors concluded that the blade crack was due to fatigue situations in resonance state and the. Axial flow fan impellers will also be subject to centrifugal forces and thus the various elements will be stressed.

The fan is designed to produce a pressure difference and hence force to cause a flow through the fan factors which determine the performance of the fan include the number and shape of the blades. An axial fan is a type of fan that causes gas to flow through it in an axial direction parallel to the shaft about which the blades rotate.