Sonic velocity measurement

The basics of the method are simple. Reflections occur at all layers in the subsurface where an appreciable change in acoustic impedance is seen by the propagating wave. This acoustic impedance is the product of the sonic velocity and density of the formation. There are actually different wave types that propagate in solid rock, but the first arrival (i.e. fastest ray path) is normally the compressional or P wave. The two attributes that are measured are... 

The AeroSizer, manufactured by Amherst Process Instmments Inc. (Hadley, Massachusetts), is equipped with a special device called the AeroDisperser for ensuring efficient dispersal of the powders to be inspected. The disperser and the measurement instmment are shown schematically in Figure 13. The aerosol particles to be characterized are sucked into the inspection zone which operates at a partial vacuum. As the air leaves the nozzle at near sonic velocities, the particles in the stream are accelerated across an inspection zone where they cross two laser beams. The time of flight between the two laser beams is used to deduce the size of the particles. The instmment is caUbrated with latex particles of known size. A stream of clean air confines the aerosol stream to the measurement zone. This technique is known as hydrodynamic focusing. A computer correlation estabUshes which peak in the second laser inspection matches the initiation of action from the first laser beam. The equipment can measure particles at a rate of 10,000/s. The output from the AeroSizer can either be displayed as a number count or a volume percentage count. 

Descriptions of sulfuric acid analytical procedures not specified by ASTM are available (32,152). Federal specifications also describe the requited method of analysis. Concentrations of 78 wt % and 93 wt % H2SO4 are commonly measured indirectly by determining specific gravity. Higher acid concentrations are normally determined by titration with a base, or by sonic velocity or other physical property for plant control. Sonic velocity has been found to be quite accurate for strength analysis of both filming and nonfuming acid. 

Barclay, F. J., T. J. Ledwidge, and G. C. Cornfield, 1969, Some Experiments on Sonic Velocity in Two-Phase Critical Flow, Symp. on Fluid Mechanics and Measurements in Two-Phase Flow Systems, Proc. Inst. Mech. Eng. 184(Part 3C) 185-194. (3)... 

The magnitude of the velocity increase accompanying deflagration in a duct can be determined from measurements made during the determination of the experimental data presented in Figure 7. Thermal choking, or sonic velocity at the exit of the burner, occurred at all mass velocities greater than approximately 32 pounds per second per square foot. This was equivalent to a linear velocity of about 3000 feet per second for the conditions of the experiment, while inlet velocities of about 250 feet per second were... 

The determination of in situ hydrates spawned a wave of research to measure hydrate properties needed for geological research and gas recovery. Several measurements were made of sonic velocity and thermal conductivity of hydrates in sediments (e.g., Stoll and Bryan, 1979 Pearson et al., 1984 Asher, 1987 Waite et al., 2005), while others measured the calorimetric properties (e.g., Rueff, 1985 Handa, 1986a,b,c,d Rueff et al 1988) needed to estimate dissociation energy. Davidson (1983) summarized hydrate properties as being similar to ice, with a few notable exceptions. Chapter 2 presents comparisons of physical property measurements of ice and hydrate. 

Pandit and King (1982) and Bathe et al. (1984) presented measurements using transducer techniques, which are somewhat different from the accepted values of Kiefte et al. (1985). The reason for the discrepancy of the sonic velocity values from those in Table 2.8 and above is not fully understood. It should be noted that compressional velocity values can vary significantly depending on the hydrate composition and occupancy. This has been demonstrated by lattice-dynamics calculations, which showed that the adiabatic elastic moduli of methane hydrate is larger than that of a hypothetical empty hydrate lattice (Shpakov et al., 1998). 

Applications The physical principle of measurement is similar to the scanning acoustic microscopy discussed in the Section 14.23, but applications and the method of data processing are essentially different. Sonic methods were used in the following applications to filled materials the effect of particle size and surface treatment on acoustic emission of filled epoxy, longitudinal velocity measurement of tungsten filled epoxy, and in-line ultrasonic measurement of fillers during extrusion. Numerous parameters related to fillers can be characterized by this non-destructive method. 

Fig. 18. Basic apparatus and experimental setup for measuring sonic velocity and stress-strain behavior simultaneously [Moseley (46)2...

Sheen, S. H. and Raptis, A. C. Active Acoustic Cross-Correlation Technique Applied to Flow Velocity Measurement in a Coal/Liquid Slurry, Proc. of Sonics/Ultrasonic Symp., 1983, 591. 

This formula gives good results for low-velocity gas flow (less than about 200ft/s), hut for high-velocity gas flows Bernoulli s equation is no longer applicable. For all velocities between zero and sonic velocities, we can assume that the part of the mainstream which is stopped by the impact tube is stopped practically isentropically. If that is correct, then the pressure measured at F, is the reservoir pressure for the flow. Thus, we can use Eq. 8.17, solved for... 

The sonic velocity is related to the sonic modulus. E, i.e. Young s modulus measured at high frequency, via the expression... 

Another useful method for measuring flexibility is to use the material s sonic modulus. The sample used should be unoriented and measured below the glass temperature. If this is done, the chain stiffness will correlate with sonic velocity that is, the greater the sonic velocity, the greater the chain stiffness. 

Figures 3.31 to 3.33 show the measured and computed sonic velocities for methane, nitrogen, and ra-hexane. The computed enthalpy is...

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