scholarly journals Ultrasonic Guided Wave Phased Array Focusing Technology and Its Application to Defrosting Performance Improvement of Air-Source Heat Pumps

Energies ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 3117 ◽  
Author(s):  
Haihui Tan ◽  
Xiaofeng Zhang ◽  
Li Zhang ◽  
Tangfei Tao ◽  
Guanghua Xu
Keyword(s):  
Power Consumption ◽  
Heat Supply ◽  
Phased Array ◽  
Guided Wave ◽  
Numerical Calculations ◽  
Stress Effect ◽  
Ultrasonic Array ◽  
Enthalpy Difference ◽  
Advance Time ◽  
Frost Layer

Previous studies have indicated that a basic frost layer negatively affects the heat-transfer efficiency and is difficult to remove using a single ultrasonic transducer. Herein, an ultrasonic phased array technology is proposed for evaporator coil defrosting. First, the dispersion curve of the guided wave in the vibration transfer plate and frosting fin is calculated, and the advance time of each ultrasonic vibrator and the ultrasonic near-field pressures under different velocities are determined through numerical calculations using the MATLAB software. Next, according to the advance time, ultrasonic array focusing is performed to remove the basic frost layer. Finally, the power consumption, heat-supply enthalpy difference, and coefficient of performance (COP) of the air-source heat pump (ASHP) unit are analysed. The theoretical analysis, numerical calculations, and experimental results consistently revealed that ultrasonic array focusing compensates for the energy dissipation and expends the effective defrosting area. Additionally, the perpendicular stress elicited by the Lamb wave and the differential transverse shear stress generated by the SH wave exceed the tensile strength and adhesion stress of the basic frost layer. The basic frost layer cracks and falls away, owing to the combination of the ultrasonic stress effect and the cavitation effect. The defrosting power consumption of the ASHP unit under ultrasonic array excitation decreases from −3.27% to 0.12%, whereas the heat-supply enthalpy difference increases from 4.47% to 10.86%. Therefore, the percentage increment of the COP is between 7.16% and 11.12%, and the power consumption of the reverse-cycle defrosting is 3–12 times that of ultrasonic array defrosting.

Lithium niobate guided-wave beam former for steering phased-array antennas

1994 ◽  
Vol 33 (26) ◽  
pp. 6194 ◽  
Author(s):  
Mario N. Armenise ◽  
Vittorio M. N. Passaro ◽  
Giuseppe Noviello
Keyword(s):  
Lithium Niobate ◽  
Phased Array ◽  
Wave Beam ◽  
Guided Wave ◽  
Phased Array Antennas ◽  
Array Antennas

Damage detection in multilayered fiber–metal laminates using guided-wave phased array

2016 ◽  
Vol 30 (5) ◽  
pp. 2113-2120 ◽  
Author(s):  
Ameneh Maghsoodi ◽  
Abdolreza Ohadi ◽  
Mojtaba Sadighi ◽  
Hamidreza Amindavar
Keyword(s):  
Damage Detection ◽  
Phased Array ◽  
Guided Wave ◽  
Fiber Metal Laminates ◽  
Fiber Metal

scholarly journals Numerical Investigation of Excitation of Various Lamb Waves Modes in Thin Plastic Films

2022 ◽  
Vol 12 (2) ◽  
pp. 849
Author(s):  
Rymantas Jonas Kazys ◽  
Justina Sestoke ◽  
Egidijus Zukauskas
Keyword(s):  
Numerical Investigation ◽  
Lamb Wave ◽  
Guided Waves ◽  
Phased Array ◽  
Ultrasonic Transducer ◽  
Guided Wave ◽  
Ultrasonic Guided Waves ◽  
Plastic Films ◽  
Thin Plastic ◽  
Wave Modes

Ultrasonic-guided waves are widely used for the non-destructive testing and material characterization of plates and thin films. In the case of thin plastic polyvinyl chloride (PVC), films up to 3.2 MHz with only two Lamb wave modes, antisymmetrical A0 and symmetrical S0, may propagate. At frequencies lower that 240 kHz, the velocity of the A0 mode becomes slower than the ultrasonic velocity in air which makes excitation and reception of such mode complicated. For excitation of both modes, we propose instead a single air-coupled ultrasonic transducer to use linear air-coupled arrays, which can be electronically readjusted to optimally excite and receive the A0 and S0 guided wave modes. The objective of this article was the numerical investigation of feasibility to excite different types of ultrasonic-guided waves, such as S0 and A0 modes in thin plastic films with the same electronically readjusted linear phased array. Three-dimensional and two-dimensional simulations of A0 and S0 Lamb wave modes using a single ultrasonic transducer and a linear phased array were performed. The obtained results clearly demonstrate feasibility to excite efficiently different guided wave modes in thin plastic films with readjusted phased array.

scholarly journals Analysis of Preload Effect in the Axisymmetric Damped Steel Wire Using Ultrasonic Guided Wave Monitoring

2020 ◽  
Vol 2 (1) ◽  
pp. 1
Author(s):  
Jothi Saravanan Thiyagarajan
Keyword(s):  
Cross Section ◽  
Steel Wire ◽  
Attenuation Factor ◽  
High Strength ◽  
Guided Wave ◽  
Stress Effect ◽  
Propagation Characteristics ◽  
Initial Tension ◽  
Safe Method ◽  
Ultrasonic Guided Wave

Guided ultrasonic wave propagation characteristics in the axisymmetric prestressed viscoelastic waveguide, using the semi-analytical finite element (SAFE) method, are studied broadly for acoustic emission monitoring. For the numerical investigation, a single high strength steel wire is considered. The SAFE method for an axisymmetric cross-section in cylindrical-coordinates is utilized to analyze the two main influencing factors of steel wire in a practical scenario, namely, material damping and initial tension. For pre-stress effect, the calculation shows that the initial tensile stress can increase and decrease the energy velocity and attenuation factor of most modal waves above the cut-off frequency, which is linear.

2-D Directional Phased Array Using Piezoelectric Paint to Detect Damages in Isotropic Plates

2009 ◽  
Author(s):  
Byungseok Yoo ◽  
Darryll J. Pines ◽  
Ashish S. Purekar
Keyword(s):  
Structural Health Monitoring ◽  
Damage Detection ◽  
Health Monitoring ◽  
Ultrasonic Testing ◽  
Phased Array ◽  
Guided Wave ◽  
In Situ Monitoring ◽  
Mode Shapes ◽  
Detection Techniques ◽  
Structural Health

Research interests in structural health monitoring have increased due to in-situ monitoring of structural components to detect damage. This can secure personal safety and reduce maintenance effort for mechanical systems. Conventional damage detection techniques known as nondestructive evaluation (NDE) have been conducted to detect and locate damaged area in structures. Ultrasonic testing, using ultrasonic transducers or electromagnetic acoustic transducers, is one of the most widespread NDE techniques, based on monitoring changes in acoustic impedance. Although the ultrasonic testing has advantages such as high sensitivity to discontinuities and evaluation accuracy, it requires testing surface accessibility, close location to the damaged area, and decent skill and training of technicians. In recent years, modal analysis techniques to capture changes of mode shapes and natural frequency of structures have been investigated. However, the technique is relatively insensitive to small amount of damage such as an initial crack which can rapidly grow in structures under cyclic loadings. In addition, structural health monitoring based on guided waves has become a preferred damage detection approach due to its quick examination of large area and simple inspection mechanisms. There are many techniques used to analyze sensor signals to bring out features related to damage. A phased array coupled with the guided wave approach has been introduced to effectively analyze complicated guided wave signals. Phased array theory as a directional filtering technique is usually used in antenna applications. By using phased array signal processing, virtually steering the array to find the largest response of source, the desired signal component can be enhanced while unwanted information is eliminated.

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