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Axial Flow Compressors and Fans
Published in Ahmed F. El-Sayed, Aircraft Propulsion and Gas Turbine Engines, 2017
A stall is a situation of abnormal airflow through single or multiple stages of the compressor, while a whole compressor stall, known as a “compressor surge,” results in a loss of engine power. This power failure may only be momentary, or it may shut the engine down completely and cause a flameout. The appropriate response to compressor stalls varies according to the engine type and situation, but it usually involves an immediate and steady decrease of the thrust in the affected engine. The most likely cause of a compressor stall is a sudden change in the pressure differential between the intake and combustion chamber. The following factors can induce compressor stall:Engine over-speedEngine operation outside specified engineering parametersTurbulent or disrupted airflow to the engine intakeContaminated or damaged engine componentsJet aircraft pilots must be careful when dropping the airspeed or increasing the throttle.
Numerical Simulation and Analysis of Combustion Stability of Aero-Engine Using Machine Learning and IIoT
Published in IETE Journal of Research, 2022
The main combustion chamber is one of the key parts of aero-engine. When the engine is working in the air, the main combustion chamber will have the alternation of lean and rich oil working conditions in a short time. The repeated changes of high power and low power working conditions will occur. It will have a direct impact on internal flow, heat release, and outlet temperature field variations, affecting working stability and flying safety [5–7]. However, acoustic coupling, acoustic interference, pressure and velocity pulsation, unstable heat release rate, and fuel flow pulsation in the combustion chamber will make the combustion unstable. The combustion stability is also affected by changes in fuel injection speed, atomization quality, pump speed, and compressor rectification blade adjustment. The dynamic interference between engine components will cause the working deviation, such as compressor stall and surge, which will lead to engine flameout [8–11]. As a result, the combustion chamber’s design must guarantee that the air load and lean, rich fuel, and gas ratio are maintained in a stable functioning range under a variety of flying situations.
Investigation on turbulent characteristic of crossflow under suction in a T-junction using Holo-Hilbert spectral analysis
Published in Journal of Turbulence, 2022
Xuefang Xu, Huaishuang Shao, Ruixiong Li, Mei Lin, Peiming Shi
As a more intuitive, direct, and adaptable method, empirical mode decomposition (EMD) has attracted much attention and has been applied in fault diagnosis [20], climate research [21], and stock price prediction [22]. Considering its huge advantage of analysing non-stationary and nonlinear time series, EMD has been used to study the flow of compressor stall [23], a high arch dam flows discharge structure under the excitation of water flow [24], and separate small-scale and large-scale motions in turbulent wall-bounded flows [25]. However, it should be noted that EMD also belongs to additive expansion methods, the nonlinear inter-mode multiplicative interactions also cannot be successfully analysed through EMD. To cure this deficiency, a new method named Holo-Hilbert spectral analysis (HHSA) was proposed by Huang [26] to give a full informational spectral representation for nonlinear and non-stationary data. The HHSA is constructed based on two or more layers of EMD to account for the variations in both the amplitude and frequency modulations, simultaneously. Considering that the HHSA has great advantages over traditional spectrum analysis methods, HHSA is adopted to analyse the crossflow of the ventilation systems under various conditions for interpreting amplitude and frequency modulations.
High-Fidelity Line Operational Simulation Evaluation of Synthetic Vision Flight Deck Technology for Enhanced Unusual Attitude Awareness and Recovery
Published in International Journal of Human–Computer Interaction, 2021
Kyle K. Ellis, Lawrence J. Prinzel, Daniel K. Kiggins, Stephanie N. Nicholas, Kathryn Ballard, Renee C. Lake, Trey J. Arthur
For the dual-engine flameout, all flight crews (n = 12) showed observed indications of startle/surprise (i.e., verbal expressions, visible pilot reactions). Post-experimental briefings confirm that all pilots were aware of volcanic activity in vicinity, but were not expecting they may encounter ash leading to dual-engine shutdown. Moreover, the pilots stated they were initially startled by the realistic auditory and motion effects of the compressor stall followed by the high number and complexity of the EICAS warnings. The flight crew startle/surprise reactions were proximate to two undesired aircraft states for Blue-Over-Brown display condition, but these did not result in unusual attitudes.