The Pre-Stall Behavior of a 4-Stage Transonic Compressor and Stall Monitoring Based on Artificial Neural Networks

Abstract

Current research concerned with the aerodynamic instability of compressors aims at an extension of the operating range of the compressor towards decreased massflow. In practice, a safety margin is maintained between operating point and stability limit to prevent the compressor from going into stall and surge. In this article, we analyze the behavior of a 4-stage transonic axial compressor before entering the unstable range and present an approach to identifying incipient surge and stall using artificial neural networks. This method is based on measurements of the unsteady static wall pressure in front of the first rotor.Analyzing the static pressure signals by using the Fast Fourier Transform shows that peripheral disturbances (modal waves) can only be identified in a small range close to nominal speed (at 95%). At lower speeds (60 to 80% of nominal speed), the investigated compressor flow enters instability by spike-type stall.Monitoring stability over the entire speed range of the compressor relies on artificial neural networks using the unsteady wall pressure signal. In the present case, artificial neural networks show to be the most useful tool to indicate approaching instability. The method works reliably for both types of instabilities, spike-type stall as well as modal waves.

Stall Warning Algorithm of Axial Compressor Based on SSA-DBN

“…In the previous studies, Methling et al [18] discussed the possibility of using an artificial neural network to identify the initial surge stall detection of the compressor. The characteristics of distorted stall precursor of the compressor are detected by neural network modeling.…”

Identification and classification of operating flow regimes and prediction of stall in a contra-rotating axial fan using machine learning

“…Using CFD, the stall mechanisms of the two fans were studied, indicating tip leakage flow and shock boundary layer interaction as the cause of the stall. Unsteady casing pressure measurements at the rotor and stator of a four-stage axial compressor were used to identify and study the stall and pre-stall behaviour of compressor, at different rotor speeds by Methling et al [24]. The stall was identified to be associated with spike-type disturbances.…”

Experiments on the Use of Signal Visualization Technique for In-Service Stall Detection in Industrial Fans

“…The request of developing warning systems of general validity [12] motivates this circumstance and identifies stall as early as possible to enable an active control system to react and suppress the incipient stall. Early warning time, according to the literature, is approximately two rotor revolutions for axial compressors [13] but perhaps ten times longer for industrial fans [14].…”