A Health Monitoring Modelling Case Study: Humidity Effects on Engine Deterioration Prediction

Asteris Apostolidis,Konstantinos P Stamoulis,S Pantelakis,K Tserpes,G Lampeas

doi:10.1051/matecconf/202134903011

Asteris Apostolidis, Konstantinos P Stamoulis + Show 3 more

Open Access

https://doi.org/10.1051/matecconf/202134903011

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Abstract

This work focuses on humidity effects of turbofan engines, in order to identify the magnitude of the error in operational conditions and the implications on maintenance decision support. More specifically, this paper employs a set of different methods, including semi-empirical corrections used in engine test beds, performance simulation models and analysis of historical data, in order to investigate the effects of humidity. We show that varying humidity can have a noticeable influence on the performance of the engine. These discrepancies cannot be currently quantified by health monitoring systems. Simulation and test bed correlations indicate a decrease of EGT of 0.35% per 1wt% of absolute humidity, which varies worldwide between 0 and 3wt%. Consequently, deviations in EGTM can be up to 1%, a figure which can be up to 12K for a modern civil turbofan. In practice, variations in ambient humidity have the potential to conceal possible deterioration in engine components. Following, the flight historical data were corresponded to historical humidity data. The two methods were identified to provide comparable results, indicating a higher EGTM for increasing ambient humidity. Overall, it was concluded that EGTM corrections for ambient humidity is an area of significant interest, especially for newer engine types where accurate diagnostics are of increasing importance.

Highlights

Engine health monitoring is a crucial function for aircraft operators and Maintenance, Repair and Overhaul (MRO) providers, for two main reasons: First, to secure a safe and reliable operation and second, to identify the maintenance needs of individual engines
Two different tools were used to examine the impact of humidity across the whole operational range of these engine types: The first is the correlations used in experimental rigs, known as test beds, where engines are tested after every shop visit
It is important to mention that the original values of EGT were measured by the engine manufacturer with the assumption of 0 wt% humidity, which means that the correction for real conditions of humidity will result in a reduced Exhaust Gas Temperature Margin (EGTM)

Summary

Introduction

Engine health monitoring is a crucial function for aircraft operators and Maintenance, Repair and Overhaul (MRO) providers, for two main reasons: First, to secure a safe and reliable operation and second, to identify the maintenance needs of individual engines. The scope of individual shop visits, or even long-term maintenance programmes is usually determined before the induction of actual engines and the necessary inspections that take place, and it is mainly based in standardised rules that take into account the accumulated flight hours and flight cycles [4] This results in the underestimation of the influence of environmental factors that can have an adverse impact in the planned type of maintenance. Exceeding a gas temperature limit, which results in negative EGTM, means that an engine has reached its operational limits and some actions are needed on the operator’s side [5]. As a result of this technical shortcoming, the main research finding that will be presented in this work can be stated as follows: In this paper, a computational framework is proposed that augments engine diagnostics by correcting on-wing reported EGTM for ambient humidity variations

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