Contact Mechanics and Materials Removal in Abradable Linings

Dr. Matt Marshall 
Dr. Jonathan Stringer
Rolls-Royce Ltd.

From the comfort of their seats, most airline passengers are unaware of the potential for millions of dollars to be lost right outside theirwindows.

The greater the gap between engine blades and the surrounding casing, the higher the fuel consumption and subsequent cost for the airline carrier. It has been estimated that by saving only one per cent of fuel consumed, the airline industry could make savings of 160 million dollars per year. The adjustment between the engine blade and casing needed to achieve this? 25 microns or half the width of a human hair. 

However, because the engine can reach temperatures of up to 1800°C, which leads to the metal distorting, it is not possible to position the blade and outer casing any closer, without risk of the two colliding – with tentially disastrous consequences.

 The solution has been to use an abradable lining inside the casing, which can be worn away safely if need be. Although aero-engine manufacturers have been using these linings for the last 40 years there has been a lack of research into how exactly they are worn.

Working alongside Rolls-Royce, this project aims to investigate the way in which the abradable lining is worn by using ultrasonic  ensors and measuring devices. 

We use ultrasonic sensors to measure the pressure distribution from a rotating blade, which is in itself a completely new area of study as previous research has been restricted to measuring static contacts.

This research will have implications for all turbomachinery, aerospace, surface coatings and wear industries. The ultrasonic element of the study could also be applied to the wheel/rail contact by researchers in the railway industry.

More efficient engines mean less costly engines, leaving the passenger and carrier to enjoy their flight.