Multistep Degradation Tendency Prediction for Aircraft Engines Based on CEEMDAN Permutation Entropy and Improved Grey–Markov Model

Table 2

Description of the selected monitoring signals for the construction of IDI series.

Index	Monitoring signal	Abbreviation	Unit
1	Total temperature at low-pressure compressor outlet	T24	°R
2	Total temperature at high-pressure compressor outlet	T30	°R
3	Total temperature at low-pressure turbine outlet	T50	°R
4	Total pressure at high-pressure compressor outlet	P30	psia
5	Static pressure at high-pressure compressor outlet	Ps30	psia
6	Ratio of fuel flow to Ps30	Phi	pps/psia
7	Bypass ratio	BPR	—