Study on Stability Analysis on Acoustic Resonance in Heat Exchanger Tube Bundles

2014 ◽  
Author(s):  
Eiichi Nishida ◽  
Hiromitsu Hamakawa
Keyword(s):  
Stability Analysis ◽  
Vortex Shedding ◽  
Gas Flow ◽  
Acoustic Resonance ◽  
Resonance Mode ◽  
Feedback Effect ◽  
Design Stage ◽  
Resonance Amplitude ◽  
Wake Oscillator ◽  
Tube Bundles

Acoustic resonance may occur in heat exchangers such as gas heaters or boilers which contain tube bundles. This resonance is classified in self-excited oscillation, and feedback effect between vortex shedding and sound field plays important role. The final goal of our study is to develop a method by which to predict the resonance attack critical gas flow velocity and maximum resonance amplitude at the design stage. In order to reach this goal, it is essential to formulate the feedback effect between vortex shedding and a resonance mode concerned, and to execute a stability analysis of the resonance mode. There are two mechanisms in the feedback process: as the acoustic resonance grows, vortex strength is increased and vortex shedding synchronization grows. This paper is concerned with the proposal of phenomenological model suitable to explain this mechanism and the formulation of these kinds of feedback mechanism with the use of this model. The model adopts vortex shedding wake oscillator model which is effective for tube vibration problems. Tube vibration movement is replaced by acoustic particle movement. Another improvement of our study is the introduction of statistical modeling of the wake oscillator to express vortex shedding synchronization effect. Here, the randomness of vortex shedding is explicitly modeled by a probability density function of the phase of the oscillator, and this function depends on the level of acoustic resonance. Based on these ideas to express the vortex/acoustics interaction, the formulas of stability analysis were derived.

Study on Modeling Method of Vortex Shedding Synchronization in Heat Exchanger Tube Bundles

2010 ◽  
Author(s):  
Eiichi Nishida ◽  
Hiromitsu Hamakawa ◽  
Azim Arshad
Keyword(s):  
Vortex Shedding ◽  
Coherence Function ◽  
Phase Fluctuation ◽  
Acoustic Resonance ◽  
Modeling Method ◽  
Resonance Level ◽  
Critical Flow Velocity ◽  
Resonant Level ◽  
Wake Oscillator ◽  
Tube Bundles

Acoustic resonance may occur in heat exchangers such as gas heaters or boilers which contain tube bundles. The purpose of this study is to develop modeling method of vortex shedding synchronization because this is the most essential part of critical flow velocity prediction. Here, acoustic resonance level dependence of spatial correlation of vortex shedding is expressed by coherence function between wake-oscillator behaviors in any two locations in the cavity. The feedback effect in synchronization of vortex shedding is represented by resonant level dependence of the wake-oscillator phase fluctuation range. This method gives the result that when resonance level increases, synchronization level in the tube bundles also increases, which seems to be a reasonable conclusion. Experimental method to identify the undefined parameters in the proposed method is also mentioned.

Acoustic Resonance in Heat Exchanger Tube Bundles—Part I: Physical Nature of the Phenomenon

1987 ◽  
Vol 109 (3) ◽  
pp. 275-281 ◽  
Author(s):  
R. D. Blevins ◽  
M. M. Bressler
Keyword(s):  
Heat Exchanger ◽  
Gas Flow ◽  
Tube Bundle ◽  
Physical Nature ◽  
Transverse Mode ◽  
Acoustic Resonance ◽  
Heat Exchanger Tube ◽  
Sound Levels ◽  
Tube Bundles ◽  
Exchanger Tube

The intense acoustic resonance resulting from gas flow across a bank of heat exchanger tubes in a duct has been investigated experimentally and theoretically. At low gas velocities, the acoustic tone emanating from tube bundles increases in proportion to the flow velocity. When the frequency approaches a bound acoustic transverse mode of the tube bundle, intense sound can result. Sound levels as high as 173 db were measured within the bundle. During resonance, the sound correlates vortex shedding from the tubes and the pressure drop increases in some bundles.

Acoustic Resonance in Heat Exchanger Tube Bundles—Part II: Prediction and Suppression of Resonance

1987 ◽  
Vol 109 (3) ◽  
pp. 282-288 ◽  
Author(s):  
R. D. Blevins ◽  
M. M. Bressler
Keyword(s):  
Experimental Data ◽  
Heat Exchanger ◽  
Vortex Shedding ◽  
Empirical Model ◽  
Acoustic Resonance ◽  
Heat Exchanger Tube ◽  
Tube Bundles ◽  
Semi Empirical ◽  
Exchanger Tube

In the first part of this series, experimental data were presented which suggest that the acoustic resonance in heat exchanger tube bundles is tied to periodic vortex shedding from the tubes. In this paper, a semi-empirical model for predicting the onset of resonance is developed. This model is compared with experimental data and other models from the literature. Methods of suppressing the resonance are developed and experimental data on their effectiveness are presented.

scholarly journals Gas-Flow Sensor Based on Self-Oscillating and Self-Sensing Cantilever

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 846
Author(s):  
Jens-Peter Zöllner ◽  
Steve Durstewitz ◽  
Jaqueline Stauffenberg ◽  
Tzvetan Ivanov ◽  
Mathias Holz ◽  
...  
Keyword(s):  
Resonance Frequency ◽  
Flow Measurement ◽  
Gas Flow ◽  
Resonance Mode ◽  
Flow Sensor ◽  
Resonance Amplitude

In this work the application of a self-sensing and self-actuating cantilever for gas-flow measurement is investigated. The cantilever placed in the flow is excited permanently at its first resonance mode. Simultaneously the resonance amplitude, the resonance frequency and the static bending of the cantilever are detected. All three sizes are related to the velocity of the gas-flow.

Study on Modeling Method of Vortex Shedding Synchronization in Heat Exchanger Tube Bundles II: Experimental Verification

2011 ◽  
Author(s):  
Eiichi Nishida ◽  
Hiromitsu Hamakawa
Keyword(s):  
Vortex Shedding ◽  
Experimental Verification ◽  
Coherence Function ◽  
Sound Field ◽  
Modeling Method ◽  
Resonance Level ◽  
Simple Method ◽  
Critical Flow Velocity ◽  
Wake Oscillator ◽  
Tube Bundles

Acoustic resonance may occur in heat exchangers such as gas heaters or boilers which contain tube bundles. This resonance is classified in self-excited oscillation, and feedback effect in vortex shedding and sound field plays important role. The purpose of this study is to develop a modeling method of the resonance level dependence of vortex shedding synchronization because this is the most essential part of critical flow velocity prediction. The level of synchronization is expressed by a coherence function between vortex shedding in any two locations in the tube bundle. Here, we introduce the wake oscillator model of vortex shedding, and based on this model, a simple method to estimate the resonance level dependence of the coherence function is proposed. In this method, the relationship of vortex shedding and the sound field in an arbitrary tube is expressed by a statistical model where the effect of resonance on the wake-oscillator is expressed by the width of the fluctuation range of phase between wake-oscillator and acoustic particle velocity. From this model, the resonance level dependence of the coherence function is derived in simple form. This method gives the result that when the resonance level increases, the synchronization level in the tube bundles also increases, which seems to be a reasonable conclusion. The results of experimental verification showed the validity of the proposed modeling method.

Analysis of the Noise Level Generated by Axial Flow Fan Composed of Radial-Bladed Centrifugal Rotor

2014 ◽  
Author(s):  
S. S. Borges ◽  
R. Barbieri ◽  
P. S. B. Zdanski
Keyword(s):  
Sound Pressure Level ◽  
Sound Pressure ◽  
Axial Flow ◽  
Acoustic Resonance ◽  
Pressure Level ◽  
Resonance Mode ◽  
Numerical Techniques ◽  
Cooling Systems ◽  
Centrifugal Fans ◽  
Motor Cooling

The objective of this work is to present, by means of experimental, analytical and numerical techniques that sound pressure level generated by radial-bladed centrifugal fans of electric motor cooling systems may be expressed by a logarithmical ratio of the peripheral velocity of rotor, volumetric flow and efficiency of the fan. The proposed methodology proved to be efficient and simple in the prediction of generated noise by radial-bladed centrifugal fans of TEFC motors with accuracy of ± 3 dB. In addition, the acoustic resonance mode of the fan cavity were determined by means of numerical simulations, which its results were validated through experiments using waterfall spectrum.

Relation between Acoustic Resonance and Vortex Shedding from Tube Banks

2020 ◽  
Vol 2020 (0) ◽  
pp. 606
Author(s):  
Yuudai YAMAGUCHI ◽  
Hayato KOCHYO ◽  
Hiromitsu HAMAKAWA ◽  
Eiichi NISHIDA ◽  
Eru KURIHARA
Keyword(s):  
Vortex Shedding ◽  
Acoustic Resonance ◽  
Tube Banks

Applicability of The Equivalent Diameter Approach to Estimate Vortex Shedding Frequency and Acoustic Resonance Excitation From Different Finned Cylinders In Cross-Flow

2021 ◽  
Author(s):  
Mohammed Alziadeh ◽  
Atef Mohany
Keyword(s):  
Strouhal Number ◽  
Vortex Shedding ◽  
Interaction Mechanism ◽  
Acoustic Resonance ◽  
Resonance Excitation ◽  
Equivalent Diameter ◽  
Effective Diameter ◽  
Finned Tubes ◽  
Vortex Shedding Frequency ◽  
Shedding Frequency

Abstract This article explores the applicability of utilizing different equivalent diameter (Deq) equations to estimate the vortex shedding frequency and onset of self-excited acoustic resonance for various types of finned cylinders. The focus is on three finned cylinder types that are commonly used in industrial heat exchangers: straight, twist-serrated, and crimped spirally finned cylinders. Within each type of fins, at least three different finned cylinders are investigated. The results indicate that at off-resonance conditions, utilizing the appropriate equivalent diameter collapses the Strouhal number data within the typical Strouhal number variations of an equivalent diameter circular, bare cylinder. However, when acoustic resonance is initiated, the onset and the peak of resonance excitation in all of the finned cylinder cases generally occurred at a reduced flow velocity earlier than that observed from their equivalent diameter bare cylinders. This suggests that although utilizing the appropriate equivalent diameter can reasonably estimate the vortex shedding frequency away from acoustic resonance excitation, it cannot be used to predict the onset of acoustic resonance in finned tubes. The findings of this study indicate that the effective diameter approach is not sufficient to capture the intrinsic changes in the flow-sound interaction mechanism as a result of adding fins to a bare cylinder. Thus, a revision of the acoustic Strouhal number charts is required for finned tubes of different types and arrangements.

scholarly journals Theoretical stability analysis of mixed finite element model of shale-gas flow with geomechanical effect

2020 ◽  
Vol 75 ◽  
pp. 33
Author(s):  
Mohamed F. El-Amin ◽  
Jisheng Kou ◽  
Shuyu Sun
Keyword(s):  
Finite Element ◽  
Stability Analysis ◽  
Shale Gas ◽  
Gas Flow ◽  
Mixed Finite Element ◽  
Mixed Finite Element Method ◽  
Element Model ◽  
Mathematical Proofs ◽  
The Stability ◽  
Shale Gas Transport

In this work, we introduce a theoretical foundation of the stability analysis of the mixed finite element solution to the problem of shale-gas transport in fractured porous media with geomechanical effects. The differential system was solved numerically by the Mixed Finite Element Method (MFEM). The results include seven lemmas and a theorem with rigorous mathematical proofs. The stability analysis presents the boundedness condition of the MFE solution.

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