Balancing of high-speed machinery: Theory, methods and experimental results

Abstract

Rotating machinery accounts for the vast majority of modern technological hardware. While the dynamic behavior of such machinery has always been important, the current emphasis on higher efficiency has resulted in the design of machines which are increasingly susceptible to vibratory phenomena. In particular, reduction in weight, coupled with increased operating speeds, have substantially increased the flexibility of rotating machinery. Thus, many types of machines are currently being designed to operate supercritically, and this trend is likely to continue. Consequently, reduction of mass unbalance in rotating machinery is often essential to ensure safe operation and reasonable life for such machines. This is particularly true for machines with flexible rotors. This paper strives to describe the three principal flexible rotor balancing methods: modal balancing, influence coefficient balancing, and the Unified Balancing Approach. Each of these methods is discussed in some detail, including analytical basis and specific implementation procedures. The methods are compared from a procedural standpoint and results from a series of comparative tests are presented. The results of these tests indicate the relative superiority, at least for this example, of the Unified Balancing Approach.