Efficient Electromagnetic Analysis and Design Techniques in Jet Engines

Abstract

A statistical electromagnetics based approach is proposed for efficient analysis of electromagnetic propagation inside harsh environments, like jet engines, to establish a communication channel inside the environment. The study of electromagnetic propagation inside the jet engine compressors that are close to turbine blades faces several difficulties due to the design complexity. The jet engine environment is an extremely complex geometry and exhibits random behavior due to the presence of moving metallic parts. The complex geometry environment combined with the inhomogeneous volumetric target render traditional analytical and simulation modeling techniques highly inefficient. To address this issue, two different approaches are proposed. The first is an innovative dynamic simulation approach based on statistical electromagnetic methods and inspired by analysis of mechanically stirred reverberation chambers.A dimension scaling method is introduced along with the dynamic simulation approach to solve the complex jet engine environment. Furthermore, the effect of excitation on the field characteristics of the dynamic system has been analyzed to prove that the dynamic system is statistically linear. In the second approach, a novel statistical excitation method is applied to develop an equivalent model for the fields generated by a fixed excitation inside a jet engine with dynamic rotating blade. Hence, the jet engine is considered as a static system without blade rotation, but with a random excitation. The dynamic and static systems have been compared using full wave simulation method and numerical methods. The results proved that there is a statistical equivalence between the dynamic and the static systems. The effect of the Doppler frequency shift on the electric field strength inside a jet engine is analyzed by using a stepwise stationary blade rotation method. The results show that the amplitude deviation due to frequency shift is negligible at all receiving probe locations. Later, the effect of blade rotation on the electric field phase variation is also analyzed. The results are very promising for the future modeling of the jet engine Doppler shift in terms of field phase time variation. A new low profile microstrip antenna array is proposed and analyzed for wireless sensor applications in extremely harsh jet engine environments. This design is to establish a communication link between the wireless sensors inside the jet engine with the receiving antennas and hence the entire system is designed for ISM band of frequency. Due to the environmental constraints, the antenna is designed to be extremely thin and flexible. The proposed antenna is designed to have a canonical beam pattern. Three different models of patch antenna arrays, circular, half circular, and hybrid rectangular circular models are designed, simulated, fabricated and experimentally measured. The proposed antennas radiate symmetrically around the normal axis Z, with a null in the boresight direction. The radiation pattern of the proposed antenna is promising for real-time applications inside a jet engine since the strongest radiation field of the antenna is pointed towards the engine blades.