Absorption Coefficient Of Liquids Research Articles

Measurement of Ultrasonic Absorption in Liquids by the Observations of Acoustic Streaming

Propagation of an ultrasonic wave through an absorbing liquid contained in a tube gives rise to a gradient of pressure along the axis which is determined by observing the velocity of flow of the liquid through a side tube connected in parallel with the main tube. The intensity of the ultrasonic wave is found by recording the voltage applied to the exciting transducer, the parameters of which are measured in the vicinity of resonance. Obstruction of the sound field by the intensity measurement is thus avoided. The observations are used to evaluate the absorption coefficients of liquids over the range 130 kc/s to 1560 kc/s. The limits and accuracy of the technique are discussed and a new theoretical approach enables the pressure gradient to be derived from second-order acoustic variables without recourse to the concept of radiation pressure.

Two-Crystal Interferometric Method for Measuring Ultrasonic Absorption Coefficients in Liquids

Methods for measuring α, the sound amplitude absorption coefficient in liquids, using two matched quartz crystals are outlined. A standard signal generator drives one of the crystals continuously. The amplitude of the resulting pressure waves is measured at the other crystal by means of a communications receiver and a voltmeter. Partial wave analysis allows the voltage observed at the second crystal to be expressed in terms of the absorption coefficient. Three cases are identified: low, high, and intermediate absorptions, and the above expression is simplified for each of these cases. Data, obtained by these methods, are presented. The internal consistency encountered suggests an accuracy of ±3%.

Radio-Frequency Bridge Methods in Ultrasonic Interferometry

The sound absorption coefficient in liquids may be shown to be simply related to the acoustic resistance of a liquid column [J. Acoust. Soc. Am. 29, 769 (A) (1957)]. It is possible to determine accurately the variations of this resistance by employing radio-frequency bridge techniques. Such a method has been used to measure the temperature dependence of the absorption coefficient of castor oil in the frequency range from 2 to 10 Mc. The experimental accuracy and consistency of the results indicate that this method may aid in removing discrepancies in the existing data. In addition, because of its extreme sensitivity the bridge-type detection system appears to be ideal for velocity and dispersion measurements.

Relation between efficiency of quartz transducers and ultrasonic absorption coefficient of liquids. II

On the basis of the investigation carried out in this Laboratory, a relationship has been worked out between the absorption coefficient of a liquid and the overall efficiency of a quartz transducer vibrating in that medium in Part I of the paper. In this paper a similar relationship is established between the absorption coefficient of the liquid and the net ultrasonic efficiency of the crystal.

Relation between efficiency of quartz transducers and ultrasonic absorption coefficient of liquids. I

Relation between efficiency of quartz transducers and ultrasonic absorption coefficient of liquids. I

A new method for the determination of the acoustic absorption coefficient in liquids

A new way to obtain the acoustic absorption coefficient in liquids by an optical method, making use of standing ultrasonic waves. Some results are given, in good agreement with the experimental results of other authors who worked with different methods at the same frequency and temperature. A noteworthy exception is the case of Benzol, for which we obtained a value much lower (about a sixth) than the generally accepted experimental value. We wish to point out here that Benzol exhibited the strongest anomalies of the experimental absorption coefficient compared with the theoretical values. Our result approximates better the ideal value.

Determination of the ultrasonic absorption coefficient in liquids by the thermal method

In liquids with a high ultrasonic absorption coefficient as, f.i. benzol, has been observed that an augmentation of the power of the piezoelectric quartz might be a cause of energy dissipation to be ascribed to cavitation and acoustic flow which whould be the origin of the high absorption coefficient. Measures are reported from which it appears that the augmentation of power really produces some uncertainty in the measure ofΔT and therefore of the coefficient α; but, anyway, by a proper proceeding it is possible to obtain for α concordant values with respect to several measurements and one sees therefore that for benzol the thermal method gives a value of the absorption coefficient very greater as the theoretical value.

Sound Absorption in Liquids: Thermal Methods

AbstractThe thermal method developed in this Laboratory for the measurement of the ultrasonic absorption coefficient in liquids has been used elsewhere in a modified form. Re‐examination of this new technique reveals that it is not capable of giving a value for the ultrasonic absorption coefficient of liquids.

A New Thermal Method for Sound Absorption in Liquids

AFTER establishing1 the equivalence of sonic and thermal energies (given by the relation I = JH, where I is the intensity of sound at the source, H is the heat produced by absorption of this sound and J the conversion factor which has the same value of 4.19 × 107 ergs/sec. as the mechanical equivalent of heat) this relationship was utilized in this Laboratory to develop a novel technique for the measurement of ultrasonic absorption coefficient in liquids. It consists of the measurement of heat produced at different points along the path of an ultrasonic beam, and its application in the formula H = H 0 exp(− 2αx) where I in the usual formula for attenuation is replaced by H because of the earlier equivalence relation. A series of measurements of absorption coefficient have been taken with this technique and the results have already been reported2 elsewhere along with full experimental details. These results have shown that the accuracy of this method is high and the values of absorption coefficient so obtained are in close agreement with those obtained by other methods of measurement.

Notizen: Determination of Ultrasonic Absorption Coefficient in Liquids by a new Technique

Notizen: Determination of Ultrasonic Absorption Coefficient in Liquids by a new Technique

A Variation of the Radiation Pressure Method of Measuring Sound Absorption in Liquids

An apparatus is described which may be used to measure the ultrasonic absorption coefficient in liquids. The transducer is one-hundred percent modulated at an audiofrequency. This produces the same frequency variation in the radiation pressure. A condenser microphone is used to detect these low frequency pressure changes. The apparatus has been tested in water over the frequency range 9–27 mc and possesses an accuracy which is comparable to that of pulse and optical methods.

The Dependence of Intensity of Sound at Source on Its Absorption Coefficient in Liquids

First Page