Abstract
This thesis is mainly concerned with the second order effects on cubical oval shaped cross-section blading. A detailed analysis is made on the variations of blade constants with reference to thickness and width of cubical oval cross section blades. Differential equations of motion are derived based on strain, allowing for the effects of second order terms, pretwist and rate of pretwist. A transformation method of solution of the differential equations which was developed by Dawson (17) is adopted for solving the equations. This method consists of transforming the original equations into a set of simultaneous first order differential equations and solving by a step-by-step finite difference process. The natural frequencies of vibration up to third mode are obtained for two sets of blades of equivalent width to thickness ratios of 15.7:1 and 7.9:1. In either case frequencies are calculated firstly including the second order terms and secondly neglecting the second order terms. Three programs were developed by the author in ALGOL to calculate i) the blade parameters ii) to check the ordinates, and iii) to compute the natural frequencies. The theoretical results obtained are compared to measured frequencies and the effect of the second order terms is shown. The cubical oval cross-section blades were manufactured by a modified shaping machine and were excited by means of an electro-magnetic exciter.