scholarly journals Efficient Azimuthal Mode Analysis using Compressed Sensing

2016 ◽  
Author(s):  
Maximilian Behn ◽  
Roman Kisler ◽  
Ulf Tapken
Keyword(s):  
Compressed Sensing ◽  
Mode Analysis ◽  
Azimuthal Mode

Azimuthal Mode Characteristics of Rotating Instability in Axial Compressor Using Compressed Sensing Method

2021 ◽  
pp. 1-53
Author(s):  
Jie Tian ◽  
Zonghan Sun ◽  
Xiaopu Zhang ◽  
Hua Ouyang
Keyword(s):  
Compressed Sensing ◽  
Dynamic Pressure ◽  
Robustness Analysis ◽  
Axial Compressor ◽  
Mode Analysis ◽  
Reconstruction Method ◽  
Sampling Point ◽  
Complex Flow ◽  
Azimuthal Mode ◽  
Rotating Instability

Abstract A signal reconstruction algorithm based on the compressed sensing (CS) theory with dual-uniform sampling point (DUSP) distribution is developed and applied to identify the circumferential mode of axial compressor. A regular failure signal pattern is found and the corresponding explanation is presented with validation. Circumferential mode analysis is applied to both numerical and experimental pressure fluctuation signals of rotating instability in the axial compressor tip region. For numerical calculations, the signal in the circumferential mode domain is reconstructed by the CS with random measurement points and DUSP respectively. The success rates and the reconstruction errors are discussed in details. It is shown that the circumferential mode reconstruction method based on CS combined with DUSP is capable to identify the complex flow modes in tip region of axial compressor. For the experimental results, high circumferential mode numbers are reconstructed based on dynamic pressure signals measured by DUSP. Circumferential mode analysis efficiency is thereby significantly improved. The time-resolved characteristics of the rotating instability (RI) is discussed. Moreover, a robustness analysis is conducted, demonstrating the ability of the CS-based method with DUSP to address fault sensor problems.

Sound Power Measurements at Radial Compressors Using Compressed Sensing Based Signal Processing Methods

2019 ◽  
Author(s):  
Jakob Hurst ◽  
Maximilian Behn ◽  
Ulf Tapken ◽  
Lars Enghardt
Keyword(s):  
Signal Processing ◽  
Compressed Sensing ◽  
Matching Pursuit ◽  
Orthogonal Matching Pursuit ◽  
Radial Mode ◽  
Mode Analysis ◽  
Sound Power ◽  
Test Rig ◽  
Azimuthal Mode ◽  
Radial Compressor

Abstract Two sound power measurement approaches were developped that are easy to install and have the ability to detect the dominant modal content by applying the modern signal processing method, Compressed Sensing. In general Compressed Sensing requires only few measurement positions for an exact reconstruction of sparse acoustic mode fields. For a current study we have chosen two Compressed Sensing algorithms. Each require separate sensor array arrangements and deliver different modal contents, from which the sound power can be derived. Firstly, an Azimuthal Mode Analysis is conducted by applying the Enhanced Orthogonal Matching Pursuit (EOMP) algorithm to a sound pressure measurement vector. The measurements are obtained by using a sensor ring array with optimized positions. In a subsequent step, the sound power is calculated by referring the detected azimuthal mode spectrum to a model describing the energy distribution over the radial mode content. Secondly, using the Block Orthogonal Matching Pursuit (BOMP) algorithm, the radial mode amplitudes are determined directly. This algorithm requires the sensors to be placed at optimized azimuthal and axial positions and reconstructs a set of dominant radial modes that occur in groups. With the objective to verify both methods, the newly designed and optimized arrays in combination with the aforementioned mode reconstruction algorithms are applied to a numerical data set. This data was provided by URANS simulations of a radial compressor set-up, which is an exact replication of an actual test rig located at the RWTH Aachen University. The introduced estimation methods perform well as shown by comparison with an exact and high resolution Radial Mode Analysis Method. In the near future, the presented measurement approaches will be applied in an experimental study performed at the radial compressor test rig.

Investigation into the Noise Characteristics Based on Rotating Instabilities Mechanism in a Multi-Stage Axial Compressor

2012 ◽  
Vol 160 ◽  
pp. 366-372
Author(s):  
Yun Dong Sha ◽  
Xian Zhi Cui ◽  
Feng Tong Zhao ◽  
Xiao Chi Luan
Keyword(s):  
Axial Compressor ◽  
Flow Region ◽  
Rotor Blades ◽  
Mode Analysis ◽  
Stable Operation ◽  
Sound Waves ◽  
Theoretical Formulation ◽  
Azimuthal Mode ◽  
Noise Characteristics ◽  
Multi Stage

Rotating instability can be observed in the tip flow region of axial compressor stage while stable operation. In order to investigate the noise characteristics in a multi-stage axial compressor, the noise inner compressor casing is measured simultaneously with the vibration of the rotor blades on a high pressure compressor component rig testing. An azimuthal mode analysis and theoretical formulation of the rotating source mechanism are applied to the unsteady pressure at the casing wall immediately upstream of the inlet plane of the rotor. It is shown that RIs might be described by a group of superimposed modes. This is the reason why RIs can be identified as an amplitude increase in a frequency band. The mode orders of RI are consecutively numbered riseing with frequency. The frequency in the source frame (ωN) closed to the frequency in the rotating frame (ωN) can be got well recovered. The results presented in this paper can be a reference for further understanding of the characteristics of unsteady flow field and the effects of the high intensity sound waves on the rotor blades.

Rotor–Stator Interactions in a 2.5-Stage Axial Compressor—Part I: Experimental Analysis of Tyler–Sofrin Modes

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Marius Terstegen ◽  
Christoph Sanders ◽  
Peter Jeschke ◽  
Harald Schoenenborn
Keyword(s):  
Predictive Accuracy ◽  
Measurement Data ◽  
Axial Compressor ◽  
Mode Analysis ◽  
Frequency Domain Method ◽  
Nonlinear Frequency ◽  
Azimuthal Mode ◽  
Flow Solver ◽  
Numerical Predictions ◽  
Timing Data

Abstract This two-part paper investigates the influence of rotor–stator interactions on the blade vibrational stresses of the first rotor, excited by the downstream stator. To this end, aeroacoustic and aeroelastic measurements and numerical setup studies for the solver TRACE are conducted in order to improve the predictive accuracy of blade vibrational stresses. Part I compares tip timing data for resonance crossings of three blisk modes to numerical predictions. Due to the single-row analysis within the linearized version of the flow solver TRACE, unsteady rotor–stator interactions are excluded by default. The findings show that leaving out these interactions in the numerical setup can lead to 97% lower vibrational stress predictions with respect to the absolute value measured. To validate the prediction of rotor–stator interactions by the nonlinear frequency domain method of TRACE, unsteady pressure measurements were conducted at the casing in the inter-row section of the first stage. The results were analyzed using an optimized measuring grid and applying a compressed sensing-based azimuthal mode analysis. Predicted azimuthal mode numbers are in accordance with the experiment, whereas amplitudes deviate from the measurements in part. Part II focuses on the prediction of blade vibrational stresses. To this end, a detailed grid study is performed and comparisons to steady and unsteady measurement data are made. In summary, this two-part paper confirms the importance of rotor–stator interactions for blade vibrational stresses excited by downstream vanes at a state-of-the-art high-pressure compressor.

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