Numerical Investigation on the Flow Mechanism of Multi-Peak Frequency Feature of Rotating Instability

2020 ◽  
Author(s):  
Hao Wang ◽  
Yadong Wu ◽  
Shaoyuan Yue ◽  
Yan’gang Wang
Keyword(s):  
Numerical Investigation ◽  
Peak Frequency ◽  
Flow Mechanism ◽  
Rotating Instability ◽  
Frequency Feature

An Experimental and Numerical Investigation Into the Mechanisms of Rotating Instability

2001 ◽  
Author(s):  
Joachim März ◽  
Chunill Hah ◽  
Wolfgang Neise
Keyword(s):  
Experimental Study ◽  
Numerical Investigation ◽  
Axial Flow ◽  
Rotating Stall ◽  
Tip Clearance ◽  
Stable Mode ◽  
Tip Clearance Flow ◽  
Double Phase ◽  
Clearance Flow ◽  
Rotating Instability

This paper reports on an experimental and numerical investigation aimed at understanding the mechanisms of rotating instabilities in a low speed axial flow compressor. The phenomena of rotating instabilities in the current compressor were first identified with an experimental study. Then, an unsteady numerical method was applied to confirm the phenomena and to interrogate the physical mechanisms behind them. The experimental study was conducted with high-resolution pressure measurements at different clearances, employing a double phase-averaging technique. The numerical investigation was performed with an unsteady 3-D Navier-Stokes method that solves for the entire blade row. The current study reveals that a vortex structure forms near the leading edge plane. This vortex is the result of interactions among the classical tip-clearance flow, axially reversed endwall flow, and the incoming flow. The vortex travels from the suction side to the pressure side of the passage at roughly half of the rotor speed. The formation and movement of this vortex seem to be the main causes of unsteadiness when rotating instability develops. Due to the nature of this vortex, the classical tip-clearance flow does not spill over into the following blade passage. This behavior of the tip-clearance flow is why the compressor operates in a stable mode even with the rotating instability, unlike traditional rotating stall phenomena.

scholarly journals Measurement of the Radius of Metallic Plates Based on a Novel Finite Region Eigenfunction Expansion (FREE) Method

2020 ◽  
Author(s):  
Ruochen Huang ◽  
Mingyang Lu ◽  
Zhijie Zhang ◽  
Qian Zhao ◽  
Yuedong Xie ◽  
...  
Keyword(s):  
Analytical Solution ◽  
Eigenfunction Expansion ◽  
Analytical Approach ◽  
Peak Frequency ◽  
Finite Region ◽  
Finite Radius ◽  
A Value ◽  
Wide Range ◽  
Frequency Feature ◽  
Tree Method

Eddy current based approaches have been investigated for a wide range of inspection applications. Dodd-Deeds model and the truncated region eigenfunction expansion (TREE) method are widely applied in various occasions, mostly for the cases that the sample is relatively larger than the radius of the sensor coil. The TREE method converts the integral expressions to the summation of many terms in the truncated region. In a recent work, the impedance of the co-axial air-cored sensor due to a plate of finite radius was calculated by the modified Dodd-Deeds analytical approach proposed by authors. In this paper, combining the modified analytical solution and the TREE method, a new finite region eigenfunction expansion (FREE) method is proposed. This method involves modifying its initial summation point from the first zero of the Bessel function to a value related to the radius of the plate, therefore makes it suitable for plate with finite dimensions. Experiments and simulations have been carried out and compared for the verification of the proposed method. Further, the planar size measurements of the metallic circular plate can be achieved by utilising the measured peak frequency feature.

scholarly journals Numerical investigation on flow mechanism in a supersonic fluidic oscillator

2021 ◽  
Vol 34 (5) ◽  
pp. 214-223
Author(s):  
Yongjun SANG ◽  
Yong SHAN ◽  
Jingzhou ZHANG ◽  
Xiaoming TAN ◽  
Yuanwei LYU
Keyword(s):  
Numerical Investigation ◽  
Flow Mechanism ◽  
Fluidic Oscillator

scholarly journals Measurement of Radius of a Metallic Ball Using Eddy Current Testing Based on Peak Frequency Difference Feature

2021 ◽  
Author(s):  
Gang Hu ◽  
Ruochen Huang ◽  
Mingyang Lu ◽  
Lei Zhou ◽  
Wuliang Yin
Keyword(s):  
Eddy Current ◽  
Test Piece ◽  
Peak Frequency ◽  
Frequency Difference ◽  
Current Sensor ◽  
Current Testing ◽  
Lift Off ◽  
Analytical Result ◽  
Current Feature ◽  
Frequency Feature

This paper proposes a linear eddy-current feature to determine the radius of a metallic ball in a non-contact manner. An electromagnetic eddy-current sensor with two coils is placed co-axially to the metal ball during measurement. It is well known that the distance between the sensor and test piece (i.e. lift-off) affects eddy-current signals. In this paper, it is found that the peak frequency feature of inductance spectrum is linear to the lift-off spacing between the centre of coil and ball. Besides, the slope of peak frequencies versus lift-offs is linked to the radius of ball. The radius of metallic balls is retrieved from the experimental and embedded analytical result of the slope. Measurements have been carried out on 6 metallic balls with different radii. The radius of the metallic ball can be retrieved with an error of less than 2 %.

scholarly journals Measurements of Thickness for Metallic Plates with Co-Axial Holes Using a Novel Analytical Method with the Modified Integration Range

2020 ◽  
Author(s):  
Wuliang Yin ◽  
Ruochen Huang ◽  
Mingyang Lu ◽  
Zhijie Zhang ◽  
Anthony Peyton
Keyword(s):  
Material Properties ◽  
Analytical Method ◽  
Peak Frequency ◽  
Upper Limit ◽  
Integration Limit ◽  
Air Core ◽  
Open Hole ◽  
Electromagnetic Sensor ◽  
Simulation Results ◽  
Frequency Feature

The existence of the hole on a plate affects the calculation of eddy current problems. Consequently, the accuracy for the prediction of the material properties decreases if the effect of the hole is not taken into account. In this paper, a novel analytical method based on the modified integration range is proposed which can address the presence of the hole. Due to the presence of the hole, the conventional Dodd-Deeds analytical solution cannot be used to calculate the inductance change. Therefore, a revised upper integration limit is introduced to replace the original limit -- ∞ when using the co-axially air-core electromagnetic sensor. With the presence of the hole, the magnitude of the received signal reduces, and the peak frequency feature changes. The analytical method is validated by measured and numerical simulation results. It is found that the upper limit is related to the radius of the open hole. With the new technique, the thickness of sample plates with holes can be estimated based on the peak frequency feature.

Experimental and Numerical Investigation of the Unsteady Endwall Flow in a Highly Loaded Axial Compressor Stator

2014 ◽  
Author(s):  
Christian Beselt ◽  
Dieter Peitsch ◽  
Ruben van Rennings ◽  
Frank Thiele ◽  
Klaus Ehrenfried
Keyword(s):  
Numerical Simulations ◽  
Pressure Distribution ◽  
Numerical Investigation ◽  
Pressure Fluctuations ◽  
Axial Compressor ◽  
Pressure Measurements ◽  
Rotating Instability ◽  
Operating Points ◽  
Measured Pressure ◽  
Highly Loaded

The unsteady endwall pressure distribution is investigated by means of highly resolved pressure measurements and numerical simulations in an axial compressor stator exhibiting the phenomenon of rotating instability. The endwall flow has been observed to play an important role in the inception of rotating instability. The statistical properties of the measured pressure fluctuations at the hub endwall of the axial compressor stator are compared for a series of blade loadings. The results allow conclusions about the location of regions being closely connected to the unsteady dynamics related to the rotating instability phenomenon. Furthermore the operating points with detected rotating instability are compared with unsteady numerical results.

An Experimental and Numerical Investigation into the Mechanisms of Rotating Instability

2002 ◽  
Vol 124 (3) ◽  
pp. 367-374 ◽  
Author(s):  
Joachim Ma¨rz ◽  
Chunill Hah ◽  
Wolfgang Neise
Keyword(s):  
Experimental Study ◽  
Numerical Investigation ◽  
Axial Flow ◽  
Rotating Stall ◽  
Tip Clearance ◽  
Stable Mode ◽  
Tip Clearance Flow ◽  
Double Phase ◽  
Clearance Flow ◽  
Rotating Instability

This paper reports on an experimental and numerical investigation aimed at understanding the mechanisms of rotating instabilities in a low speed axial flow compressor. The phenomena of rotating instabilities in the current compressor were first identified with an experimental study. Then, an unsteady numerical method was applied to confirm the phenomena and to interrogate the physical mechanisms behind them. The experimental study was conducted with high-resolution pressure measurements at different clearances, employing a double phase-averaging technique. The numerical investigation was performed with an unsteady 3-D Navier-Stokes method that solves for the entire blade row. The current study reveals that a vortex structure forms near the leading edge plane. This vortex is the result of interactions among the classical tip-clearance flow, axially reversed endwall flow, and the incoming flow. The vortex travels from the suction side to the pressure side of the passage at roughly half of the rotor speed. The formation and movement of this vortex seem to be the main causes of unsteadiness when rotating instability develops. Due to the nature of this vortex, the classical tip clearance flow does not spill over into the following blade passage. This behavior of the tip clearance flow is why the compressor operates in a stable mode even with the rotating instability, unlike traditional rotating stall phenomena.

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