Ultrasonic Radiation Pressure Research Articles

Position dependence of the standing-wave radiation pressure quadrupole projection on a sphere applied to drop shape.

There have been decades of interest in using the ultrasonic radiation pressure of standing waves to deform nearly spherical objects. An analytical approach sometimes associated with the present author involves approximating projections of the radiation pressure on spheres small in comparison with the wavelength and calculating the response to that projection. In 1981, for small fluid spheres, some terms in the quadrupole projection were published along with the dependence on the size and location of the sphere. An associated application was the flattening of levitated drops in air which are attracted toward velocity antinodes of a standing wave having horizontal equiphase surfaces. In subsequent applications of those results, the predicted analytical dependence on the location of the drop is frequently neglected. For the case of small weakly deformed drops in air in normal gravity, that omission is shown to result in an overestimation of the deformation and of the magnitude of the quadrupole radiation pressure projection. The present discussion simplifies the early results when applied to oblate drops and illustrates the consequence of including the position dependence on the modified small deformation. For large trapped oblate bubbles in water (also reviewed), the shape and location depend on the size.

Upgrading Atmospheric Residue by Simultaneous Employment of Ionic Liquid, Ultrasonic and Thermal Cracking

In this study the effect of simultaneous employment of ultrasonic wave radiation, chemical substance of ionic liquid and operating conditions of thermal cracking is investigated experimentally on upgrading the atmospheric residue (AR) of a crude oil atmospheric distillation tower. Five main factors of this process that are investigated are ionic liquid concentration, ultrasonic wave power, ultrasonic radiation time, temperature and pressure. According to Box-Behnken Design, 46 experiments are conducted. Then, the proper experimental condition of this process is determined and hence, based on Multilevel Categoric Design the efficiency of seven different kinds of ionic liquids is compared. According to this design, 14 experiments are conducted. The results of 46 experiments conclude that this process is able to upgrade AR and even the simultaneous employment of ionic liquid, ultrasonic and thermal cracking cause a synergistic effect on AR upgrading. Also, the results of 14 experiments indicate that 1-Propyl boronic acid-3-decylimidazolium bromide is a desirable ionic liquid for this process.

A focused lens for measuring object response to modulated radiation pressure

An ultrasonic lens was designed and tested for use in modulated radiation pressure experiments for the purpose of exciting and identifying the low frequency modes of objects in water. The lens was designed to produce a focused beam, and care was taken to minimize the spherical aberration introduced by the lens. This was done by carefully specifying the shape of the lens surface that was then machined using a computer-controlled lathe. The lens was placed in contact with an electrically excited piezoceramic plate. The quality of the focused sound field was tested and found to display properties predicted by simple models of the focal plane wave-field. The lens was then used to drive low-frequency modes of elastic objects in water using modulated ultrasonic radiation pressure in a way previously summarized involving a commercially made focused transducer [T. D. Daniel et al., J. Acoust. Soc. Am. 140, 3123 (2016)]. [Work supported by ONR.]

Geometric approximation of radiation stress projections for canonical objects

Modulated ultrasonic radiation pressure facilitates the selective excitation of modes of objects through modulation of appropriate surface stress projections [P. L. Marston and R. E. Apfel, J. Acoust. Soc. Am. 67, 27–37 (1980)]. For some large objects, it can be impractical to evaluate the needed stress projections using standard analytical or computational methods. For highly reflecting objects geometric approximations may provide useful insight into the relevant stress projections. The simplest projection gives the translational radiation force on the object. In that case, ray analysis of the far-field scattering was shown to recover the radiation force on large perfectly reflecting spheres in plane waves [P. L. Marston, J. Acoust. Soc. Am. 120, 3518–3524 (2006)]. In the present research, the appropriate force limit is also recovered through integrating a geometrically approximated local stress projection on the object’s surface. Appropriate limiting forces for other canonical objects or situations invo...

Development of strawberry pollination system using ultrasonic radiation pressure

An ultrasonic pollination device was developed to achieve effective artificial pollination of strawberries in plant factories with artificial light. Hundreds of ultrasonic transducer were used to obtain several tens of force [mN]. The phase of each transducer was appropriately controlled, and focused on one point in space. The force was modulated at 20 to 30 Hz which is the characteristic frequency of strawberry flower. The pollination experiments were conducted using the strawberry variety “Akai Shizuku”. A marketable rate of strawberry fruit in the ultrasonic pollination plot reached the highest 91.7% at 40 Hz.

AUTOMATIC CONTROL OF THE ORE SUSPENSION SOLID PHASE PARAMETERS USING HIGH-ENERGY ULTRASOUND

Context. The authors have solved the urgent problem of controlling automatically the parameters of solid ore suspension aimed for conversion thus increasing the end product quality and facilitating the choice and adhearance to the concentration specifications. Objective. The research aims at developing the method of obtaining operational data as to iron ore characteristics while concentrating, namely distribution of solid pulp particles as to their sizes and estimated grade applying multi-channel ultrasonic measurements. Method. In order to solve the problem of controlling automatically the parameters of solid ore suspension, the authors suggest the method of measuring the intensity of high-frequency bulk ultrasonic waves covering a fixed distance in a measuring chamber containing ore suspension under the influence of ultrasonic vibrations and in case of their absence. The calculated correlations of the measured values make it possible to determine the parameters of solid ore suspension. Besides, while measuring we can observe the formation of gamma-radiation and low-frequency bulk ultrasonic waves in the ore suspension flow. It is possible to measure the intensity of gamma-radiation and lowfrequency bulk ultrasonic waves covering the fixed distance if the measuring chamber contains some reference fluid and the ore suspension flow under ultrasonic vibrations and in the absence thereof. The intensity of ultrasonic vibrations influencing the suspension flow is changed according to the relevant law. Results. The dynamic effects of high-frequency ultrasound provide a theoretical basis and a practical approval of the method controlling the solid phase of iron ore pulps in order to displace the particles of the required grain-size class to the measuring zone and to determine the grade in ore particles. The developed purpose-designed programme realizes a numerical analysis and graphical representation of simulation results of changing solid pulp particle-sizes under the controlled influence of high-energy ultrasonic radiation pressure. Conclusions. The authors have devised the method for controlling the distribution of the grade in crushed ore particle-size classes in the pulp flow by means of measuring the changes in the distribution parameters of high- and low-frequency ultrasonic waves as well as gamma-radiation. The method is different from the existing ones by the fact that in the course of measuring, the crushed ore particles of the required size and density are displaced to the measuring zone by exposing the pulps to the high-energy ultrasound influence thus increasing the measurement accuracy by 0.76%.

Experimental Research on the Levitation Support Way of Ultrasonic Thrust Bearing

In this paper, two ways of levitation support of ultrasonic thrust bearing are disscussed. Based on the mechanism of the near-field ultrasonic levitation, the front cover of the piezoelectric transducer is designed as conical structure.The ultrasonic radiation pressure which distributes on the conical surface can be decomposed into the axial and radial supporting the levitation subject bidirectionally. Finnally contrast experiments are carried out, indicating that when the requirement of levitation mass being satisfied, the way of bidirectional support runs more stably compared with the pure way of the axial levitation support.It supposes that the way of bidirectional levitation support is more conducive to improve the rotating speed of the rotor.

Ultrasonic particle size fractionation in a moving air stream

Identification of bio-aerosol particles may be enhanced by size sorting before applying analytical techniques. In this paper, the use of ultrasonic acoustic radiation pressure to continuously size fractionate particles in a moving air stream is described. Separate particle-laden and clean air streams are introduced into a channel and merged under laminar flow conditions. An ultrasonic transducer, mounted flush to one wall of the channel, excites a standing ultrasonic wave perpendicular to the flow of the combined air stream. Acoustic radiation forces on the particles cause them to move transverse to the flow direction. Since the radiation force is dependent upon the particle size, larger particles move a greater transverse distance as they pass through the standing wave. The outlet flow is then separated into streams, each containing a range of particle sizes. Experiments were performed with air streams containing glass microspheres with a size distribution from 2–22 μm, using a centerline air stream velocity of approximately 20 cm/s. An electrostatic transducer operating at a nominal frequency of 50 kHz was used to drive an ultrasonic standing wave of 150 dB in pressure amplitude. The microsphere size distributions measured at the outlet were compared with the predictions of a theoretical model. Experiments and theory show reasonable correspondence. The theoretical model also indicates an optimal partitioning of the particle-laden and clean air inlet streams.

X-ray elastography: Modification of x-ray phase contrast images using ultrasonic radiation pressure

The high resolution characteristic of in-line x-ray phase contrast imaging can be used in conjunction with directed ultrasound to detect small displacements in soft tissue generated by differential acoustic radiation pressure. The imaging method is based on subtraction of two x-ray images, the first image taken with, and the second taken without the presence of ultrasound. The subtraction enhances phase contrast features and, to a large extent, removes absorption contrast so that differential movement of tissues with different acoustic impedances or relative ultrasonic absorption is highlighted in the image. Interfacial features of objects with differing densities are delineated in the image as a result of both the displacement introduced by the ultrasound and the inherent sensitivity of x-ray phase contrast imaging to density variations. Experiments with ex vivo murine tumors and human tumor phantoms point out a diagnostic capability of the method for identifying tumors.

0133 固気二相流噴流による超音波表面加工(OS1-6 噴流,後流および剥離流れの流動解析と応用,オーガナイズドセッション)

Sandblast techniques that gas-solid jet impinges on surface of the work are known to process a work surface. Many cases gas is air in general and solid particles are metal, plastics and ceramics etc. The solid particles are accelerated by gas flow and impacts on the work and process it's surface. However the solid particles stream out with gas flow without an impact for fine particles because of large viscosity. For fine processing by means of fine solid particles the viscosity resistance becomes serious obstacle to process surface of the work. When ultrasonic is radiated on the solid particles ultrasonic radiation pressure acts on the solid particles and accelerates it. The radiation pressure is determined by a medium, an acoustic intensity and frequency of the ultrasonic.

Liquid jet response to internal modulated ultrasonic radiation pressure and stimulated drop production

Experimental evidence shows that a liquid jet in air is an acoustic waveguide having a cutoff frequency inversely proportional to the jet diameter. Ultrasound applied to the jet supply liquid can propagate within the jet when the acoustic frequency is near to or above the cutoff frequency. Modulated radiation pressure is used to stimulate large amplitude deformations and the breakup of the jet into drops. The jet response to the modulated internal ultrasonic radiation pressure was monitored along the jet using (a) an optical extinction method and (b) images captured by a video camera. The jet profile oscillates at the frequency of the radiation pressure modulation and where the response is small, the amplitude was found to increase in proportion to the square of the acoustic pressure amplitude as previously demonstrated for oscillating drops [P.L. Marston and R.E. Apfel, J. Acoust. Soc. Am. 67, 27-37 (1980)]. Small amplitude deformations initially grow approximately exponentially with axial distance along the jet. Though aspects of the perturbation growth can be approximated from Rayleigh's analysis of the capillary instability, some detailed features of the observed jet response to modulated ultrasound are unexplained neglecting the effects of gravity.

Excitation of a vertical liquid capillary jet waveguide by modulated ultrasonic radiation pressure

The excitation of a liquid capillary jet issuing from a nozzle is investigated using internally applied modulated ultrasonic radiation pressure. The transducer used here is more efficient than one used in prior studies [J. B. Lonzaga et. al., J. Acoust. Soc. Am. 116, 2598 (2004)] and is suitable for nozzle velocities as low as 25 cm/s. At low velocities, the liquid jet is significantly tapered. As a consequence of the taper, the acoustic cutoff frequency increases with increasing distance from the nozzle. For ultrasound propagation down the jet from the nozzle, finite‐element calculations of the radiation pressure show that the radial stress at the cutoff location is significantly larger than at any other region of the jet. Two distinct capillary modes exist and are conjectured to be excited near the cutoff location by modulated radiation pressure: one traveling upward and the other traveling downward. In a certain range of modulation frequencies, the latter is an exponentially growing mode and leads to the forced disintegration of the jet into liquid drops. Excitation of the growing mode at the nozzle is achieved for low‐speed jets by using carrier frequencies close to or below the nozzle cutoff frequency. [Work supported by NASA.]

Supersonic shear imaging

There is a great interest for developing in vivo quantitative imaging of the shear tissue properties. This can be achieved by using an ultrafast ultrasonic imaging device able to follow in real time the propagation of low frequency transient shear wave in the body. We have developed such an ultrafast scanner that can give up to 5.000 images/s. From the spatio-temporal evolution of the elastic field a local inversion algorithm allows to recover the shear modulus and viscosity map without the limitations induced by diffraction. Transient shear sources are induced by ultrasonic radiation pressure generated by the ultrasonic probe array. The most interesting configuration that induces high amplitude shear waves used a sonic shear source that moves at supersonic velocities. In vitro and in vivo results will be presented that demonstrate the great interest of supersonic shear imaging.

Acoustically modulated x-ray phase contrast imaging

We report the use of ultrasonic radiation pressure with phase contrast x-ray imaging to give an image proportional to the space derivative of a conventional phase contrast image in the direction of propagation of an ultrasonic beam. Intense ultrasound is used to exert forces on objects within a body giving displacements of the order of tens to hundreds of microns. Subtraction of images made with and without the ultrasound field gives an image that removes low spatial frequency features and highlights high frequency features. The method acts as an acoustic ‘contrast agent’ for phase contrast x-ray imaging, which in soft tissue acts to highlight small density changes.

Optical detection of the response of liquid jets to internal modulated ultrasonic radiation pressure

A liquid jet in air is an acoustic waveguide having a cutoff frequency inversely proportional to the jet diameter. Ultrasound applied to the jet supply liquid can propagate down the jet when the carrier frequency is near-to or above the cutoff frequency. The jet response to the internal acoustic radiation pressure of amplitude modulated ultrasound was monitored along the jet using an optical pseudo-extinction method. The jet profile oscillates at the frequency of the radiation pressure modulation and, where the response is small, the amplitude was found to increase in proportion to the square of the acoustic pressure amplitude as previously demonstrated for oscillating drops [P. L. Marston and R. E. Apfel, J. Acoust. Soc. Am. 67, 27–37 (1980)]. Small amplitude deformations initially grow approximately exponentially with axial distance along the jet. Modulated radiation pressure can be used to stimulate large amplitude deformations and the breakup of the jet into drops. [Work supported by NASA.]

Radiation pressure of standing waves on liquid columns and small diffusion flames

The radiation pressure of standing ultrasonic waves in air is demonstrated in this investigation to influence the dynamics of liquid columns and small flames. With the appropriate choice of the acoustic amplitude and wavelength, the natural tendency of long columns to break because of surface tension was suppressed in reduced gravity [M. J. Marr-Lyon, D. B. Thiessen, and P. L. Marston, Phys. Rev. Lett. 86, 2293–2296 (2001); 87(20), 9001(E) (2001)]. Evaluation of the radiation force shows that narrow liquid columns are attracted to velocity antinodes. The response of a small vertical diffusion flame to ultrasonic radiation pressure in a horizontal standing wave was observed in normal gravity. In agreement with our predictions of the distribution of ultrasonic radiation stress on the flame, the flame is attracted to a pressure antinode and becomes slightly elliptical with the major axis in the plane of the antinode. The radiation pressure distribution and the direction of the radiation force follow from the dominance of the dipole scattering for small flames. Understanding radiation stress on flames is relevant to the control of hot fluid objects. [Work supported by NASA.]

Active stabilization of liquid capillary bridges using optically sensed modal amplitudes

Cylindrical capillary bridges consisting of liquid between two circular supports naturally become unstable and break when the length of the bridge exceeds its circumference for the situation where the weight or buoyancy of the bridge can be neglected. This is the Rayleigh–Plateau (RP) slenderness limit which is relevant to the management of liquids and to the formation of liquid drops. We have demonstrated methods of suppressing this instability based on the optical sensing of the instantaneous modal amplitude and the rapid adjustment of the axial distribution of applied radial stress. This applied stress may be the result of ultrasonic radiation pressure [M. J. Marr-Lyon et al., J. Fluid Mech. 351, 345–357 (1997)] or electrostatic stresses from an array of electrodes [M. J. Marr-Lyon et al., Phys. Fluids (accepted)]. We have stabilized bridges as much as 42% beyond the RP limit by phasing the stress so that the effective modal spring constant becomes positive; however, the modal damping is then decreased. The closed-loop response includes terms associated with boundary-layer damping and the sensor’s response time. The analysis indicates that damping of short bridges may be enhanced by reversing the feedback phase. [Work supported by NASA.]

Results of Experiments on the Significance of Ultrasonic Radiation Pressure in Ultrasonic Cleaning in Water and Aqueous Solutions

SUMMARYMeasurements have been made of ultrasonic radiation pressure (measured through balancing of the weight of a measuring cone) versus temperature during the application of ultrasound at 33+34 kHz in water and aqueous solutions used in ultrasonic cleaning. Results are given in the form of diagrams; they are discussed in relation to degassing and nature of salts used.

Containerless protein crystal growth in rotating levitated drops

A method for growing protein crystals in a containerless environment using an ultrasonic–electrostatic hybrid levitator is evaluated. In this approach, a single protein solution droplet bearing a surface charge is electrostatically levitated and acoustically rotated along a horizontal axis during the crystal nucleation and growth phases. Sample rotation is induced by ultrasonic streaming and radiation pressure applied in addition to the electrostatic levitation force. This unique approach is developed in order to create controlled crystal growth conditions which would reproduce some of the aspects of the low-gravity environment. We present the outcome of a development effort and feasibility study showing the successful growth of lysozyme and thaumatin crystals suspended within the bulk of quiescent liquid protein solutions inside rotating droplets also containing a very small concentration of agarose. Even though the crystals are not growing in a completely gelled medium and rotation is required for their long-term suspension, there are indications that a convectionless crystal growth environment has been obtained within the rotating drop, and that artificial flow can be introduced in a controlled manner by imposing drop shape oscillations.

Driven and freely decaying nonlinear shape oscillations of drops and bubbles immersed in a liquid: experimental results

Large-amplitude oscillations of drops and bubbles immersed in an immiscible liquid host have been investigated using ultrasonic radiation pressure techniques. Single levitated or trapped drops and bubbles with effective radius between 0.2 and 0.8 cm have been driven into resonant shape oscillations of the first few orders. The direct coupling of driven drop shape oscillations between the axisymmetric l=6 and l=3 modes has been documented as well as the interaction between axisymmetric and non-axisymmetric l=3 and l=2 modes. Effective resonant energy transfer from higher- to lower-order modes has been observed together with a much less efficient energy transfer in the reverse direction. The first three resonant modes for bubbles trapped in water have also been excited, and mode coupling during driven and free-decaying oscillations has been measured. The evidence gathered thus far indicates that efficient drop resonant coupling between a higher- and a lower-order mode occurs when the characteristic frequency of the latter mode roughly coincides with a harmonic resonance.