727 results about "Acoustic speed" patented technology

Apparatus (15, 30) and methods for performing acoustical measurements are provided having some and preferably all of the following features: (A) the system (15, 30) is operated under near-field conditions; (B) the piezoelement (40) or piezoelements (40, 48) used in the system are (i) mechanically (41, 49) and electrically (13, 16) damped and (ii) efficiently electrically coupled to the signal processing components of the system; (C) each piezoelement (40, 48) used in the system includes an acoustical transformer (42, 50) for coupling the element to a gaseous test medium (9); (D) speed of sound is determined from the time difference between two detections of an acoustical pulse (81, 82) at a receiver (40, FIG. 3; 48, FIG. 7); (E) cross-correlation techniques are employed to detect the acoustical pulse at the receiver; (F) forward and inverse Fourier transforms employing fast Fourier transform techniques are used to implement the cross-correlation techniques; in such a mathematical manner that the peak of the cross-correlation function corresponds to the detection of a pulse at the receiver and (G) stray path signals through the body (31) of the acoustic sensor (15, 30) are removed from detected signals prior to signal analysis. Techniques are also provided for performing acoustical measurements on gases whose thermodynamic properties have not been measured and on mixtures of compressible gases. Methods and apparatus (29) for performing feedback control of a gas of interest in a mixture of that gas and a carrier gas are provided in which the controlled variable is the flow of the carrier gas.

In industrial sensing applications at least one parameter of at least one fluid in a pipe 12 is measured using a spatial array of acoustic pressure sensors 14,16,18 placed at predetermined axial locations x1, x2, x3 along the pipe 12. The pressure sensors 14,16,18 provide acoustic pressure signals P1(t), P2(t), P3(t) on lines 20,22,24 which are provided to signal processing logic 60 which determines the speed of sound amix of the fluid (or mixture) in the pipe 12 using acoustic spatial array signal processing techniques with the direction of propagation of the acoustic signals along the longitudinal axis of the pipe 12. Numerous spatial array-processing techniques may be employed to determine the speed of sound amix. The speed of sound amix is provided to logic 48, which calculates the percent composition of the mixture, e.g., water fraction, or any other parameter of the mixture, or fluid, which is related to the sound speed amix. The logic 60 may also determine the Mach number Mx of the fluid. The acoustic pressure signals P1(t), P2(t), P3(t) measured are lower frequency (and longer wavelength) signals than those used for ultrasonic flow meters, and thus is more tolerant to inhomogeneities in the flow. No external source is required and thus may operate using passive listening. The invention will work with arbitrary sensor spacing and with as few as two sensors if certain information is known about the acoustic properties of the system. The sensor may also be combined with an instrument, an opto-electronic converter and a controller in an industrial process control system.

A method and apparatus is provided to analyze a dual wall structure having at least one hollow core therein and having the same unknown material sound velocities in walls and in post as well. A transducer is located in at least two different positions with respect to the structure, whereby the transducer propagates an ultrasonic wave toward the dual wall structure. A portion of the ultrasonic wave is reflected back to the transducer. One wave traverses a portion of the dual wall structure that has a core filled with a medium having a known material acoustic property. A second wave traverses a portion of the post that has an unknown material sound velocity. From time of flight measurements of the above mentioned waves, the wall thickness and core shift, if any, can be determined.

Aspects of this invention include a downhole tool having first and second radially offset ultrasonic standoff sensors and a controller including instructions to determine at least one of a drilling fluid acoustic velocity and a drilling fluid attenuation coefficient from the reflected waveforms received at the standoff sensors. The drilling fluid acoustic velocity may be determined via processing the time delay between arrivals of a predetermined wellbore reflection component at the first and second sensors. The drilling fluid attenuation coefficient may be determined via processing amplitudes of the predetermined wellbore reflection coefficients. The invention advantageously enables the acoustic velocity and attenuation coefficient of drilling fluid in the borehole annulus to be determined in substantially real-time.

A method and an apparatus for enhancing fluid mixing. The method comprises the following: (a) configuring a duct to have an effective outer wall, an effective inner wall, a cross-sectional shape, a first cross-sectional area and an exit area, the first cross-sectional area and the exit area being different in size; (b) generating a first flow at the first cross-sectional area, the first flow having a total pressure and a speed equal to or greater than a local speed of sound; and (c) generating a positive streamwise pressure gradient in a second flow in proximity of the exit area. The second flow results from the first flow. Fluid mixing is enhanced downstream from the duct exit area.