A wide bandwidth spectrometer for rapid ultrasonic absorption measurements in liquids

Abstract

An acoustic near plane-wave absorption spectrometer has been developed for use in small samples of liquid (30 ml) over bandwidths of up to 60 MHz, using a two transducer short-pulse transmission technique. The instrument is controlled by computer, and on-line digital signal processing is used to correct for transducer insertion, radiation coupling, and the transient responses of transmitter and receiver electronics. The raw data acquisition time is short and the instrument in its present form could be used to estimate absorption at 100-ms intervals. The instrument can be used on both stationary chemical systems and systems undergoing chemical reaction. Experimental results are presented that show excellent agreement with absorption measurements by traditional (slower) techniques.

The Detection of Structural Transformations in Kaolin Suspensions by Ultrasound

“…The equipment used to measure ultrasonic attenuation and velocity dispersion spectra of kaolin suspensions is a broadband ultrasonic spectrometer which has been described in detail elsewhere (15) and therefore will only be summarized here. The spectrometer consists of a high-voltage pulse generator which feeds a piezoelectric transducer at one end of a 36-mm cube test cell, into which a liquid test sample can be placed.…”

The Effects of Flocculation on the Propagation of Ultrasound in Dilute Kaolin Slurries

“…Equation [2] reduces to the well-known Einstein relation (9) eff ϭ (1 ϩ K) at low concentrations. The shape factor K of a particle is defined by Vand (10) as K ϭ 5/(2Ј) where Ј is the ratio of particle volume to volume of particle plus volume of "attached" liquid as a result of its nonspherical shape and is given by Simha (4) as K ϭ 64a/(15l ) for platelet-shaped particles, where a(ӷ l ) is the radius of a circle with the same area as the particle face and l is the particle thickness.…”

Ultrasonic wave propagation in concentrated slurries – The modelling problem

“…The samples were prepared by dilution with deionised distilled water from a 40wt% suspension to obtain a range of concentrations between 1.5%v/v and 33%v/v. The attenuation measurements were made using a broad band (70MHz) spectrometer instrument built in-house many years ago [27]. Figure 3 shows the experimental results obtained at 20 MHz and the corresponding predictions of the standard ECAH/LB model.…”