The mutual resistance of transducer arrays is investigated in order to design arrays with improved performance for high intensity sounds at a given frequency. This work proposes the theory that the mutual resistance is related to the loading effects of pressure waves propagated from a piston driver on the surface of another driver. Using this interpretation, the important characteristics of the mutual resistance of two piston drivers are explained and the conditions for local maxima in the mutual resistance are easily determined. On the basis of analyses of the interactions between a driver and acoustic pressure waves, we propose a method to determine the driver radius and the distance between two drivers that give maximum mutual radiation resistance. To evaluate the proposed method, the total resistance of a transducer array is calculated using the formulas for mutual and self-resistance established by Pritchard. The results of the calculations of the total resistances of arrays with many drivers show that a transducer array with drivers arranged sparsely can achieve a larger value of the radiation power per unit area as well as better radiation efficiency than an array in which the drivers are in a closely packed arrangement at a given frequency.

Effects of mutual impedance on the radiation characteristics of transducer arrays

A method and apparatus for the in-process measurement of internal particulate temperature utilizing ultrasonic tomography techniques to determine the speed of sound through a specimen material. Ultrasonic pulses are transmitted through a material, which can be a multi-phase material, over known flight paths and the ultrasonic pulse transit times through all sectors of the specimen are measured to determine the speed of sound. The speed of sound being a function of temperature, it is possible to establish the correlation between speed of sound and temperature, throughout a cross-section of the material, which correlation is programmed into a computer to provide for a continuous in-process measurement of temperature throughout the specimen.

Ultrasonic tomography for in-process measurements of temperature in a multi-phase medium

Unburnt gas density measurement in a spherical combustion bomb by infinite-fringe laser interferometry

The disclosure relates to a method for determining a temperature in a pressurized flow path of a gas turbine comprising the steps of sending an acoustic signal from an acoustic signal emitting transducer across a section of the pressurized flow path, detecting the acoustic signal with a receiving transducer, measuring the time needed by the acoustic signal to travel from the acoustic signal emitting transducer to the receiving transducer, calculating the speed of sound, and calculating the temperature as a function of the speed of sound, the heat capacity ratio (□) and a specific gas constant (R spec ) of the gas flowing in the pressurized flow path. Besides the method, a gas turbine with a processor and transducers arranged to carry out such a method is disclosed.

Gas turbine temperature measurement

A communication device includes a speaker, a microphone, and a processor connected to the speaker and the microphone. The processor is arranged for calculating ambient temperature by playing a test sound on the speaker, measuring a transit time of the test sound from the speaker to the microphone, and determining the ambient temperature from the measured transit time. A method of calculating ambient temperature by using a communications device having a speaker, a microphone and a processor is also disclosed. The method can be used for monitoring ambient temperatures of machinery and for detecting fire conditions.

Acoustic-based temperature sensing in telephones

Measuring apparatus for suddenly varying gas temperatures in internal reciprocating engines utilizing ultrasonic waves

A new type of receiving array has been designed and constructed for the purpose of visualizing an object by using the ultrasonic wave at low frequency. The array consists of 24 receiving elements around three coaxial circles on a spherical surface. The multiplication of three additive outputs, each of which is the sum of the eight element outputs on a circle, is performed for the signal processing of the array. After theoretical and experimental studies, it has been proven that the array proposed is appropriate for the high‐directional receiver in the ultrasonic visualization system. A preliminary experiment on imaging the object in the air has been carried out.

Coaxial circular spherical array for ultrasonic imaging

The frequency of a sound wave is changed from the original one by passing through the rapidly temperature changing gas. The new technique for measuring the varying gas temperature by detecting the frequency change of the passing ultrasonic wave was applied to the temperature measurement of combustion gas in a four cycle reciprocating engine. For the check of the measured temperature using this new technique, the measured sound velocity was compared with that by the conventional direct sound velocity measuring method. As a result of the experiment, it was concluded that the new measuring technique was reliable.

Measurement of Combustion Gas Temperature of Internal Combustion Engine by Use of Ultrasonic Wave

Gas Temperature Measurement Using Ultrasonic Waves

1,073,644. Ultrasonic temperature measurement. AGENCY OF INDUSTRIAL SCIENCE & TECHNOLOGY, JAPAN. July 3, 1964, No. 27609/64. Heading H4D. An apparatus for determining the rapidlychanging temperature of a gas comprises a transmitting transducer and at least one spaced receiving transducer arranged in the gas, the temperature being calculated in terms of a frequency difference between transmitted and received sound waves or between sound waves arriving at two receiving transducers. In the embodiment shown in Fig. 1, a generator 5 drives a transmitting transducer 4. Signals from two receiving transducers 2, 3, or from transducers 3 and 4 are compared in frequency by a frequency detector 6 coupled to a computor 20 which calculates the gas temperature at a given time in terms of the temperature at the instant an ultrasonic signal is transmitted or passes transducer 2. A mathematical treatment is given.

Shuji Shibata

Papers

Measuring apparatus for suddenly varying gas temperatures in internal reciprocating engines utilizing ultrasonic waves

Coaxial circular spherical array for ultrasonic imaging

Measurement of Combustion Gas Temperature of Internal Combustion Engine by Use of Ultrasonic Wave

Gas Temperature Measurement Using Ultrasonic Waves

Gas-temperature measuring apparatus utilising ultrasonic waves