ANALYTICAL REDUNDANCY IN THE AUTOMATIC CONTROL SYSTEM OF AN AIRCRAFT TURBOJET BYPASS ENGINE BASED ON OPTIMAL OBSERVERS

Abstract

An analytical redundancy in the automatic control system of a bypass turbojet engine
(ACS turbofan engine) based on optimal observers is proposed. This article is based on previously
obtained results in previous author's works and is a generalization and analysis of these results in
order to develop a methodology for improving the fault tolerance of ACS turbofan engines. This
method is based on the use of optimal observers: the Kalman filter and the Yazvinsky filter, consistent
with the mathematical model of the ACS turbofan engine. The analysis of the mathematical model of
the ACS was carried out using the least squares method in a moving window. The accuracy of identification
of the mathematical model and the required delay time are ensured by optimizing the width
of the moving window. Estimated with the help of optimal observers, the output vector of the ACS
turbofan engine includes the following parameters: the rotor speed of the low-pressure compressor
rotor nв, the rotor speed of the high-pressure compressor nk, the air pressure behind the highpressure
compressor PK, the gas temperature behind the low-pressure turbine TT. When modeling the
Kalman filter, a correlation analysis of the input signals was preliminarily carried out. The rationale
for the advantage of the adaptive Yazvinsky filter compared to the Kalman filter is given. The results
of mathematical modeling of the algorithmic method of reserving the measurement channel of the
ACS turbofan engine based on the data of flight tests of a bypass engine of the PS-90A type as part of
the main narrow-body aircraft TU-214 both in stationary and transient modes are presented. Statistical
analysis of errors in estimation of the output vector of ACS turbofan engines based on the Kalman
and Yazvinsky filter has been carried out. It is shown that the proposed analytical redundancy algorithm
ensures the fulfillment of the requirements for the accuracy and stability of estimates of the
output vector of ACS turbofan engines when using the Yazvinsky filter and can be recommended for
use in advanced ACS turbofan engines. Based on the results proposed redundancy method, a direction
for further research has been formed.