Advanced materials mean advanced engines

Abstract

In this, the third Finniston Lecture, the recent advances in aero engine technology made possible by interdisciplinary collaboration between materials scientists and design and manufacturing engineers are reviewed. Of crucial importance is the efficient and cost effective design of component geometries with due regard for material properties and manufacturing process capability. The three operating parameters that most directly define the thrust and fuel consumption of an aircraft gas turbine – fan airflow, or diameter, overall pressure ratio, or compressor delivery temperature, and turbine inlet temperature – are in turn largely dependent on these capabilities. As bypass ratios of commercial turbofans increase, the weight of the large diameter components becomes increasingly important. Titanium and composite materials, each with their own advanced manufacturing techniques, allow thrusts of 100 000 lb to be achieved at acceptable weight. Overall pressure ratio is a major influence in improving fuel consumption. The resulting temperature determines the choice of material – nickel alloy or advanced titanium, and detail design of components in this area is important to make full use of the material capability. High pressure turbine blades represent a most complex design challenge. Nickel alloys have developed to a third generation single crystal standard and ceramics offer a prospect of even higher temperature capability. It is concluded that planning from the start to have dual use application in civil and defence markets is the most cost effective route to further progress.