Langevin Transducer Research Articles

The Effect of the Movement of a Passive Reflector on the Atomization of a Levitating Drop

Abstract This study investigates the instability of distilled water drops under acoustic levitation induced by the movement of a reflector toward the transducer. The experimental setup consisted of a passive concave reflector and a Langevin transducer in a uniaxial-resonance configuration. The experiment consists of achieving a stable levitation of the droplet and then moving the reflector constantly toward the transducer, shortening the distance h between them (reflector-transducer). All experiments were recorded using a high-speed camera to analyze the drop’s behavior. The results revealed three distinct instabilities: radial atomization occurred when the drop volume (VD ) was ≤ 3.74 μl, beyond which central atomization was observed. A third instability is observed when a low reflector velocity (Vr < 0.67 mm/s) is used, where the droplet exhibited modes of oscillation with pulsed central atomization.

Non-contact mechanical Q-factor measurement system based on electromagnetic acoustic transducer

The mechanical quality factor (Q-factor), which is the reciprocal of the vibration loss constant, is one of the most important parameters in vibration engineering; however, there are no methods for its precise measurement. Q-factor databases are thus commonly used. This study proposes a completely non-contact measurement system for the Q-factor that combines non-contact excitation (achieved using an electromagnetic acoustic transducer) with non-contact support (achieved using near-field ultrasonic levitation based on two Langevin transducers). The proposed method was used to measure the Q-factor for a stainless steel (SUS304) sample (thin cylindrical rod with a diameter of 1.5 mm and a length of 80 mm)and a duralumin (A2017). The 5 times average Q-factor was 2010 with standard deviation of 50 for stainless steel (SUS304), and 49,000 with standard deviation of 3900 for duralumin (A2017). The proposed method also allowed for the measurement of Young’s modulus, resulting in 217.17 ± 0.34 GPa for stainless steel (SUS304), and 71.39 ± 0.20 GPa for duralumin (A2017).

Dynamic stability of a nitinol Langevin ultrasonic transducer under power and current tracking conditions

The Langevin transducer is widely used in medical and industrial ultrasonics, typically comprising a piezoelectric ceramic stack preloaded between two end-masses. A principal operational challenge is that, depending on the target application or operational environment, piezoelectric ceramics commonly experience elevated temperatures promoting nonlinear dynamic behaviours, often reducing operational performance. Transducers can be operated via burst excitation to mitigate this, but such methods can have limited efficacy, particularly at elevated temperatures. A novel emergent approach is the incorporation of shape memory Nitinol into the transducer, where its temperature-dependent microstructural phase transformations can compensate for changes in the mechanical properties of the piezoelectric ceramics. However, the ability to maintain dynamic stability under power and current tracking, common methods used to ensure stability of Langevin transducers in practical applications, remains unknown. In this research, a cascaded Nitinol Langevin transducer is used to demonstrate its practical application potential. Dynamic stability is assessed whilst power and current levels are tracked in operation. Stable operating frequency, electrical impedance, and vibration amplitude are shown, using a combination of methods including electrical impedance analysis and laser Doppler vibrometry. This research demonstrates the practical application of Langevin transducers incorporating shape memory materials, including with dynamic stability at elevated temperatures.

Non-Contact Multi-Degree-of-Freedom Motor Based on Hybrid Electromagnetic-Piezoelectric Drive Mode

A new non-contact ultrasonic motor consisting of a Langevin transducer, an electromagnetic device, and a spherical rotor is presented, and the designed motor is theoretically analysis and experimentally verified. The designed motor is driven by a mixture of near-field acoustic levitation and electromagnetism, and the electromagnetic platform is controlled by three stacked piezoelectric actuators to control the deflection direction, thus driving the spherical rotor to achieve the same angle of deflection and self-propagation. By exciting the Langevin transducer under the rotor, the high-frequency vibration of the stator disc causes the air between the stator disc and the rotor to be squeezed periodically, and when the air pressure in the gap is larger than the external atmospheric pressure, the levitation force generated by the stator is larger than the gravity of the rotor, thus levitating the rotor, and when the rotor deflects, it can still achieve stable levitation because of its special geometry. The proposed new motor is expected to be used in applications requiring high output torque and micro-displacement.

A Timoshenko-Ehrenfest beam model for simulating Langevin transducer dynamics

The Langevin transducer is a widely used power ultrasonic device across both medical and industrial applications, from orthopaedic surgery to drilling and welding. It is a sandwich-type device which typically consists of piezoelectric ceramic rings between two metallic end-masses. The transducer is commonly operated at a particular resonant mode to deliver ultrasonic vibrations to a target structure of interest, and is generally modelled using approaches including the transfer matrix method and electromechanical equivalent circuit methods. Here, we propose a variational framework to study the dynamics of the Langevin transducer based on the Timoshenko-Ehrenfest beam theory and Hamilton's principle. The variational equation derived from this model is then discretized by the standard finite element method with spectral elements. To verify the proposed one-dimensional electromechanical model, the computed resonance frequencies, or natural frequencies, of the one-dimensional model are compared to those of a three-dimensional finite element model with respect to varying geometry parameters characterizing the transducer. The results of the reduced one-dimensional and full three-dimensional models are then compared to those measured through an experimental investigation consisting of laser Doppler vibrometry. This is undertaken for the first ten eigenfrequencies, including longitudinal and bending modes, where normalized amplitudes and vibration mode shapes are reported. The close correlation between modelling and experiment demonstrates that the proposed one-dimensional electromechanical model can deliver results consistent with the full three-dimensional model and from experiment, thus verifying a rapid and reliable method for studying the free vibrations and dynamics of the Langevin transducer which accounts for the axial vibrations of the piezoelectric ceramic stack in all cases.

A novel rotary ultrasonic motor based on multiple Langevin transducers: design, simulation, and experimental investigation

Traveling wave rotary ultrasonic motors (TRUSMs) have been applied in optical systems, robotics, biomedical and other fields. However, the disadvantages such as short working life, driving performance degradation, and low energy utilization significantly limit the long-term and stable operation of TRUSMs in advanced fields like aerospace mechanisms. To address the above issues, a novel rotary ultrasonic motor based on multiple Langevin transducers is proposed in this paper. First, the structural design, driving principle and general design criteria are described in detail. Then, the structural parameters are optimized by finite element simulation analysis. Second, a prototype is assembled controllably. Subsequently, the impedance test and vibration measurement are carried out. The results show that the traveling wave is successfully generated on the tooth-ring, and all the Langevin transducers are excited to the first-order longitudinal vibration modes, which strongly verify the correctness of design principle. Finally, the driving performance experiment is carried out. The experimental results show that the no-load speed is 62 r min−1 under the pre-pressure of 10 N. The stalling torque is 0.94 N m at the driving voltage of 500 Vp-p. The response characteristics show that the start/stop time are 4.6/5.5 ms, and the angular displacement resolution of clockwise/counterclockwise driving are 6.7/10.2 μrad. The motor proposed in this paper not only exhibits relatively high output performance with excellent vibration characteristics, but also maintains compactness of the structure. The sandwiched structure design effectively avoids the problem that the bonded-type piezoceramic rings in conventional TRUSMs are prone to damage or fall-off when vibrating for a long time. Furthermore, the general design criteria provide a new approach to develop high performance rotary ultrasonic motors. The proposed novel ultrasonic motor is expected to meet the demand for long-term and stable operation in aerospace mechanisms.

Development of Amplitude Measurement System for Ultrasonic Vibration Assisted Micro Forming

Microforming is a process that involves forming a material through plastic deformation at a micro level. However, this method encounters an issue at the micro-scale known as the size effect. There are several new approaches to overcome these difficulties, one of which is using Ultrasonic Vibration Assisted (UVA) micro forming. UVA micro forming is a forming method by applying high-frequency vibrations to the workpiece to reduce forming forces, increase smooth zone, reduce surface roughness, and increase accuracy. A bolted Langevin transducer is needed to produce vibration, which converts electrical signals into acoustic signals in the ultrasonic frequency range. Therefore, the vibration characteristics must be considered in detail to find the best parameters in the micro forming process. This study aims to develop an amplitude measurement system for UVA micro forming. Several things that need to be considered in designing a measurement system are pre-stress characteristics, resonant frequency of the machine, and the amplitude of the vibration generated by the system. Firstly, a pre-stress test was carried out by tightening the pre-stress bolt slowly until the resonant frequency did not change. Then, the resonant frequency is measured using signal generator, oscilloscope, transducer, and resistor to determine the system’s resonant frequency. Finally, the vibration amplitude is measured by observing the displacement at the end of the punch using a digimatic indicator. The result shows that the resonance frequency that produces longitudinal vibration for UVA micro forming system is 28,720 Hz, with a pre-stress of 30 MPa with torque of 14.36 Nm, and total displacement on the normal axis is 9 μm.

A cascaded Nitinol Langevin transducer for resonance stability at elevated temperatures

Across power ultrasonics and sensing, piezoelectric ultrasonic transducers commonly experience degradation in mechanical, electrical, and dynamic performance due to the relatively high sensitivity of piezoelectric materials to changes in temperature. These changes, arising for example through high excitation voltages or environmental conditions, can lead to nonlinear dynamic behaviours which compromise device performance. To overcome this, the excitation signal to the piezoelectric material is often pulsed, mitigating the influence of temperature rises. However, there remain constraints on suitable candidate piezoelectric materials for power ultrasonic devices. As a novel approach to mitigating the influence of temperature on the properties of piezoelectric materials, the phase-transforming shape memory alloy Nitinol is incorporated into the piezoelectric stack of a Langevin power ultrasonic transducer, in a cascade formation. The underlying principle is that the nonlinear hardening response of Nitinol to rising temperature can be used to dynamically compensate for the nonlinear softening of the piezoelectric materials. Thus, the dynamic response of the transducer can be linearised at elevated excitation levels. In this study, two configurations of Langevin transducer are designed and characterised. One transducer incorporates a Nitinol middle mass, and in the second, titanium. A combination of electrical and thermomechanical characterisation is undertaken, where it is demonstrated that the nonlinear softening of the piezoelectric stack can be mitigated through control of the Nitinol microstructure. The vibration amplitudes of the Nitinol-middle cascaded transducer are higher and more stable when the Nitinol is austenite rather than a combination of martensite and austenite at room temperature. It has also been shown that the vibration amplitude and resonance frequency of Nitinol-middle cascaded transducer remain stable as temperature changes from 20 °C to 45 °C, dependent of the excitation voltage. Moreover, the self-heating experiment demonstrates the resonance stability of the Nitinol-middle cascaded transducer for continuous operation.

Multi-modal transducer-waveguide construct coupled to a medical needle.

Annually, more than 16 × 109 medical needles are consumed worldwide. However, the functions of the medical needle are still limited mainly to cutting and delivering material to or from a target site. Ultrasound combined with a hypodermic needle could add value to many medical applications, for example, by reducing the penetration force needed during the intervention, adding precision by limiting the needle deflection upon insertion into soft tissues, and even improving tissue collection in fine-needle biopsy applications. In this study, we develop a waveguide construct able to operate a longitudinal-flexural conversion of a wave when transmitted from a Langevin transducer to a conventional medical needle, while maintaining high electric-to-acoustic power efficiency. The optimization of the waveguide structure was realized in silico using the finite element method followed by prototyping the construct and characterizing it experimentally. The experiments conducted at low electrical power consumption (under 5 W) show a 30 kHz flexural needle tip displacement up to 200 μm and 73% electric-to-acoustic power efficiency. This, associated with a small sized transducer, could facilitate the design of ultrasonic medical needles, enabling portability, batterization, and improved electrical safety, for applications such as biopsy, drug and gene delivery, and minimally invasive interventions.

Design and Characterization of Ultrasonic Langevin Transducer 20 kHz Using a Stepped Horn Front-Mass

Ultrasonication is a method that is widely used in various fields. One of its applications is to accelerate the process of homogenization, emulsification, and extraction. In the ultrasonicator system, the transducer is an extremely important device. The resonant frequency, longitudinal vibration amplitude, and electromechanical coupling are the targets in designing an ultrasonic transducer. In this investigation, the main contribution was the development of a simple and effective method for mechanically tuning the resonant frequency of the transducer by adding mass to the front end of the mass or stepped horn. This study also aimed to obtain optimal results by examining the effects of geometric dimensions, bolt prestress, stress distribution, resonant frequency, amplitude, and electrical impedance. The ultrasonic transducer model was designed with a resonant frequency of 20 kHz and simulated using the finite element analysis. The steps involved included calculating the dimensions and geometric structure of the transducer, modeling using the finite-element method, and experimental validation. The simulation results and measurements showed that the series resonant frequency, electrical impedance, and effective electromechanical coupling of the Model-4 transducer 16∙13 mm radiator configuration were 20.15 kHz, 100 Ω, and 0.2229 from the simulation results, and 20.17 kHz, 24.91 Ω, and 0.2033 from the measurement results. A percentage difference, or relative error, of 0.1% was obtained between the simulation and the experimental results for this Model-4 with bolt prestressing at 15 kN.

Design of a low-frequency ultrasound diagnostic sensor based on skin mechanical impedance

Skin integrity assessment is a very important matter in the nursing care, especially for patients with low mobility. However, the methodology of skin analysis is limited by a lack of reliable yet portable tools. In this paper, a new sensor is proposed for skin mechanical impedance characterisation, aiming to provide an objective assessment of skin health. The device consists in a microcontroller connected to a Langevin transducer. Using the vector control method, the reference vibration of the transducer is assured, and the mechanical impedance is observed. To ensure the repeatability of the measurements, tests in the morning and in the afternoon were taken. To verify if the device can distinguish sites with different mechanical properties on the same body, tests were made on 2 different body sites: the palm of the hand and the volar forearm. Measurements of skin hydration were also taken, to find a potential correlation of these parameters and skin acoustical mechanical impedance. Results have shown that the measurements provided by the device are mostly reliable, and reveal a fair correlation between mechanical impedance and hydration, in the level of stratum corneum, the outermost layer of skin. Also, the device is able to show the difference on the mechanics of the skin in the different body sites tested, independently of the hydration.

Dynamic resonance frequency control for a resonant-type smooth impact drive mechanism actuator

Multimodal piezoelectric actuators combine multiple vibration modes to achieve specific motions for precise actuation, or to enhance the output performance. For such a combination, the operating frequency ratio is necessarily an integer constraint. However, the resonance frequencies of target modes can be mismatched in assembly, and shift easily during operation, limiting the actuator applications. Therefore, we proposed a dynamic resonance frequency control method for multimodal piezoelectric actuators and applied it to a resonant-type smooth impact drive mechanism actuator. Passive piezoelectric parts were deployed on a Langevin transducer and connected with a field effect transistor (FET) switch. As a pulse width modulation (PWM) signal continuously adjusting the electrical boundary of these passive parts, the first longitudinal L1 mode’s resonance frequency was dynamically controlled to match the third L3 mode’s frequency with a ratio of two, generating a quasi-sawtooth displacement to drive a rotor. Experimental results indicated that the prototype’s L1 frequency can be continuously tuned from 25.715 to 24.76 kHz at 27 ℃, and the corresponding frequency ratio was adjusted from 1.953 to 2.028. Multimodal resonance frequency static matching was confirmed by changing the switching signal’s duty ratio. The L1 and L3 mode driving voltages were 50 Vp-p, and 23 Vp-p, respectively, and the speed of the rotor was 133.7 r/min. Dynamic resonance frequency control was realized with a feedback control system. As the driving PZT temperature increased to 70.5 ℃, both modes were matched and maintained resonance for 400 s. The results demonstrate that this method is conducive to improving actuator performance.

Determination of the Temperature-Dependent Resonance Behavior of Ultrasonic Transducers Using the Finite-Element Method

PurposeLangevin transducers are ultrasonic transducers that convert electrical into mechanical energy through the piezoelectric effect. This class of transducers achieves the highest efficiency in their mechanical resonance. Studies have shown that the resonant frequency changes with temperature. The aim of this contribution is to reproduce this temperature-dependence resonance frequency as accurately as possible with FEM simulations.MethodsTherefore, the temperature-dependent resonance behavior of Langevin transducers is examined experimentally. A FEM model is created on the basis of temperature-dependent measured material coefficients. Using parameter correlations and optimization algorithms, the FEM model is fitted and validated by experimental results. Six variants of Langevin transducers are examined in the range from 30 °C to 80 °C with resonance frequencies between 34 and 38 kHz. They differ in three geometries and two materials.ResultsThe experimental results show that the resonance frequencies decrease with increasing temperatures by 5.0–19.4 Hz/°C, depending on the material and geometry. As decisive parameters for the model fitting of the FEM results, three function-dependent stiffness coefficients of the piezoelectric material PZT8 and the Young’s moduli of the metallic materials are determined by parameter correlation.ConclusionThrough the targeted fitting of these function-dependent parameters, the calculation of the resonance frequencies of Langevin transducers can be qualitatively and quantitatively improved, independent of shape and material.

Compact aerial ultrasonic source integrating the transverse vibration part with the bolt-clamped Langevin transducer

We have previously developed a compact circular vibrating plate aerial ultrasonic source with a grooved uniform rod that can produce a large vibration displacement by using piston vibration and emit intense sound waves perpendicular to the vibration surface. In this paper, to create a compact ultrasonic source that can radiate intense aerial ultrasonic waves, we produced a compact aerial ultrasonic source integrating the transverse vibration part with a bolt-clamped Langevin transducer and we investigated the sound source characteristics. These results demonstrated that compared with a conventional source, the length of our source was shorter, the sound pressure was higher, and its structure was simpler.

Analysis on electric impedance-controlled active ultrasonic horn in radial vibration

As a key component of high-powered ultrasonic vibration systems, ultrasonic horns play an important role in various practical application scenarios. Recent advances in longitudinal ultrasonic horns have enabled them to magnify the Langevin transducer's mechanical vibration and efficiently transmit the mechanical vibration to the mechanical load. However, limited research has been devoted to active radial ultrasonic horns in radial vibration. Here we propose an electric impedance-controlled active radial ultrasonic horn (ARUH) capable of tuning both resonance frequency and displacement magnification in radial vibration. The resulting device consists of a radially polarized piezoelectric ring connected with adjustable electric impedance and two metal rings with variable sections. The underlying mechanism is that the change of the converted mechanical impedance of the piezoelectric material by the external electric impedance connected to the piezoelectric material modulates the resonance frequency and displacement magnification of the ARUH. It can be found that the resonant frequency shifts to higher frequencies as the resistance increases and the resonant frequency shifts to lower frequencies as the inductance and capacitance increase, while the displacement magnification has the opposite trend to the resonance frequency. For example, the resonance frequency of the constant-section radial horn is 41130.2 Hz. When the inductance increases from −0.007 to 0.007H, the resonance frequency shifts from 41171.3 to 34606.2 Hz and the displacement magnification moves from 1.189 to 3.5. The experiments are conducted to verify the effectiveness of the resulting device, which is in good agreement with the simulated results and theoretical predictions. Our design with functionality and flexibility opens up possibilities for the design of ARUHs and may find important application prospects in diverse fields such as cold-drawn steel tubes and ultrasonic plastic welding.

Ultrasonic Enhancement of Chondrogenesis in Mesenchymal Stem Cells by Bolt-Clamped Langevin Transducers.

We recently investigated the design and fabrication of Langevin-type transducers for therapeutic ultrasound. Effect of ultrasonic energy arising from the transducer on biological tissue was examined. In this study, the transducer was set to radiate acoustic energy to mesenchymal stem cells (MSCs) for inducing differentiation into cartilage tissue. The average chondrogenic ratio in area was 20.82% in the control group, for which no external stimulation was given. Shear stress was applied to MSCs as the contrast group, which resulted in 42.66% on average with a 25.92% minimum rate; acoustic pressure from the flat tip causing transient cavitation enhanced chondrogenesis up to 52.96%. For the round tip excited by 20 Vpp, the maximum differentiation value of 69.43% was found, since it delivered relatively high acoustic pressure to MSCs. Hence, the results from this study indicate that ultrasound pressure at the kPa level can enhance MSC chondrogenesis compared to the tens of kHz range by Langevin transducers.

High-Frequency Ultrasonic Radiator Power Increase by Means of Summation of Vibrations of Symmetrically Arranged Langevin Transducers

The article focuses on the research of processes of summation of ultrasonic vibrations of individual Langevin transducers symmetrically arranged on a common summator. This design could be used to solve the problem of increasing the power of a high-frequency ultrasonic radiator by means of the summation of the vibrations of individual Langevin transducers. The results of the presented theoretical and experimental investigations supported the possibility of summation of symmetrical diametrical vibrations when they are transformed into longitudinal vibrations. As a result, a new design scheme for high-frequency radiator construction was developed that provides symmetry and uniformity of vibration amplitude distribution of piezoceramic elements. This made it possible to eliminate the damage of piezoceramic elements. The article establishes that an acoustic power (continuous mode) of 1450 W at an efficiency of 78% is achieved when the vibrations from 9 to 11 of symmetrically arranged Langevin transducers at a resonant frequency of 30.05 kHz with an amplitude of 26 µm are summed. The use of this ultrasonic high-frequency radiator with increased power will provide intensification of processes in various areas of industry.

Modeling and Measurement of an Ultrasound Power Delivery System for Charging Implantable Devices Using an AlN-Based pMUT as Receiver.

Ultrasound power delivery can be considered a convenient technique for charging implantable medical devices. In this work, an intra-body system has been modeled to characterize the phenomenon of ultrasound power transmission. The proposed system comprises a Langevin transducer as transmitter and an AlN-based square piezoelectric micro-machined ultrasonic transducer as receiver. The medium layers, in which elastic waves propagate, were made by polydimethylsiloxane to mimic human tissue and stainless steel to replace the case of the implantable device. To characterize the behavior of the transducers, measurements of impedance and phase, velocity and displacement, and acoustic pressure field were carried out in the experimental activity. Then, voltage and power output were measured to analyze the performance of the ultrasound power delivery system. For a root mean square voltage input of approximately 35 V, the power density resulted in 21.6 µW cm-2. Such a result corresponds to the data obtained with simulation through a one-dimensional lumped parameter transmission line model. The methodology proposed to develop the ultrasound power delivery (UPD) system, as well as the use of non-toxic materials for the fabrication of the intra-body elements, are a valid design approach to raise awareness of using wireless power transfer techniques for charging implantable devices.

Acoustic and Thermal Characterization of Therapeutic Ultrasonic Langevin Transducers under Continuous- and Pulsed Wave Excitations.

We previously conducted an empirical study on Langevin type transducers in medical use by examining the heat effect on porcine tissue. For maximum acoustic output, the transducer was activated by a continuous sinusoidal wave. In this work, pulsed waves with various duty factors were applied to our transducer model in order to examine their effect on functionality. Acoustic power, electro-acoustic conversion efficiency, acoustic pressure, thermal effect on porcine tissue and bovine muscle, and heat generation in the transducer were investigated under various input conditions. For example, the results of applying a continuous wave of 200 VPP and a pulse wave of 70% duty factor with the same amplitude to the transducer were compared. It was found that continuous waves generated 9.79 W of acoustic power, 6.40% energy efficiency, and 24.84 kPa acoustic pressure. In pulsed excitation, the corresponding values were 9.04 W, 8.44%, and 24.7 kPa, respectively. The maximum temperature increases in bovine muscle are reported to be 83.0 °C and 89.5 °C for each waveform, whereas these values were 102.5 °C and 84.5 °C in fatty porcine tissue. Moreover, the heat generation around the transducer was monitored under continuous and pulsed modes and was found to be 51.3 °C and 50.4 °C. This shows that pulsed excitation gives rise to less thermal influence on the transducer. As a result, it is demonstrated that a transducer triggered by pulsed waves improves the energy efficiency and provides sufficient thermal impact on biological tissues by selecting proper electrical excitation types.

Simulation and experimental investigation of an ultrasound system with cavitation in concentric zone

Nowadays, ultrasonic cavitation has been successfully used for the degradation of organic pollutants. However, many sonotrodes employed for wastewater treatment are excited to present a longitudinal vibration mode. Thus, the strongest cavitation generally occurs at the tip end of the sonotrodes or the inner walls of ultrasound baths, resulting in severe erosion of the vibrating metal surface caused by ultrasonic cavitation, even though the sonotrodes are made of titanium alloy. In addition, recontamination is possible due to corrosion of the sonotrode. To avoid the above issues, a novel ultrasound system composed of a cylindrical sonotrode and a Langevin-type transducer, is proposed for generating cavitation only in the concentric zone of the cylindrical sonotrode. The first-order longitudinal vibration and the radial vibration are simultaneously stimulated in the Langevin transducer and the cylindrical sonotrode, respectively, to produce the focused cavitation at the concentric zone of the sonotrode. At first, the finite element simulation is conducted to confirm the planned vibration of the ultrasound system and to compute its sound pressure. Subsequently, the prototype of the proposed ultrasound system is manufactured and assembled for vibration measurements. Finally, experimental investigations are carried out on the ultrasound system prototype. By the aluminum foil experiments, the cavitation bubbles occurred in the center of the cylindrical sonotrode. The erosion area increased with the increase of the working power and processing time. After treating the methyl violet solution by ultrasonic cavitation for 60 min, the methyl violet in the solution is reduced by 60%, which certainly will help the development of an appropriate flow system for dye degradation. • An ultrasound system for dye wastewater treatment without re-contamination is proposed, simulated, and experimental investigated. • Cavitation bubbles were only produced at the center of the ring sonotrode. • Concentration of methyl violet solution after ultrasonic treatment decreased significantly.