Technical Note 2 - Turbine engine bolt balancing

In turbine engine discs with many bolts or heavy bolts, you may want to consider optimizing the arrangement of bolts to aid in overall stage unbalance. In turbine engines like the J44 with a bladed disc with blades all as one piece, there is not an option to arrange the blades. Bolt balancing can aid in producing a better balanced stage.

The basic process is similar to optimizing blade arrangements.

  1. Number the bolts 1 to N with a permanent marker.

  2. Weigh each bolt on a precision pan scale.

  3. Create a set at by creating an account, and then click the "+Add blade set" on the "Blade sets" page. Enter the weights for each bolt.

  4. Optionally measure the disc unbalance on a balancing machine and enter the unbalance in the settings page. Only perform this step if not already using the blade arrangement to compensate for disc unbalance.

  5. Click "Optimize" to get a precision optimization using technology developed for leading turbine companies. You can see how much the new ordering will help compared to the initial random ordering by looking at the initial unbalance calculation compared to the new unbalance calculation. This will help to get an idea if bolt balancing is a good idea on a regular basis.

  6. Assemble the bolts using the optimized order.

  7. Consider repeating the process for the nuts, which are designed to have different weights on some engines, to aid in balancing. This procedure gives a good initial starting point.

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