Hypersonic velocities

Brillouin scattering of laser light in liquids has been studied by several authors. Shapiro etal. 233) measured hypersonic velocities in various liquids and obtained a Brillouin linewidth of 0.011 cm" in methylene chloride but of less than 0.002 cm in benzene, carbon disulfide and chloroform. The broadening of the Brillouin components arises from damping of thermal phonons and is closely connected with the viscosity coefficient of the medium. From the measured linewidths, the lifetimes of the phonons responsible for Brillouin scattering at 89 45 were calculated to be 4.8 x 10 sec for methylene chloride and 7.6 x 10 sec for toluene. 

The longitudinal hypersonic velocity vi of an isotropic sample is calculated from Eq. (27), provided the outer angles Uf and Ug are specified, according to Eq. 

Another approach to determining the viscoelastic properties of dense microemulsions at high frequencies is to conduct ultrasonic absorption experiments. In such experiments it has been found that the percolation process is correlated to a shift of the ultrasonic dynamics from a single relaxation time to a distribution of relaxation times [121]. Other experiments showed an increase in the hypersonic velocity for samples at and beyond the percolation threshold. The complex longitudinal modulus deduced from such experiments is also correlated with the occurrence of the percolation phenomenon, which suggests that the velocity dispersion is clearly correlated with structural transformations [122]. 

HIVF. The Hypersonic Velocity Impact Fusion thermal spray coating process. Hob. The so-called ceramic hobs (flat surfaces for supporting cooking ware on cookers) are usually made from glass ceramic sheets. 

The principle of the method is to use Fabry-Perot spectroscopy to measure the frequency shift in laser light scattered through 90° after passage through a parallel polymer sheet. The hypersonic velocity Vs is obtained from the equation... 

Knape EG, Torell LM (1975) Hypersonic velocities and compressibilities for some molten nitrates. J Chem Phys 62 4111 115... 

Interestingly, the shape of the wake is similar to that developed behind a hypersonic blunt body where the flow converges to form a narrow recompression neck region several body diameters downstream of the rear stagnation point due to strong lateral pressure gradients. The liquid material, that is continuously stripped off from the droplet surface, is accelerated almost instantaneously to the particle velocity behind the wave front and follows the streamline pattern of the wake, suggesting that the droplet is reduced to a fine micromist. 

Multiplexed diode laser sensors have also been applied for measurements of gas temperature, velocity, and H2O partial pressures in hypervelocity air flows at the Calspan University of Buffalo Research Center s (CUBRC) Large Energy National Shock Tunnel (LENS Tunnel) in Buffalo, New York [12]. The sensors were developed to provide quantitative characterization of the facility operation and, in particular, the freestream flow properties as a function of time. The measurements were recorded using a hardened probe, which contained critical optical components and photodetectors, that was installed directly into the hypersonic shock-tunnel near the nozzle exit to minimize complications due to boundary layers and facility vibration. 

The primary component of the hypersonic flame spraying process is an internal combustion device, which produces an "exhaust" similar to that found in a rocket. This exhaust is produced by the internal combustion of oxygen and fuel gases. A combustion flame temperature of approximately 5500°F. is created, with exhaust velocities of 4,500 feet per second. 

Brillouin scattering measures the velocity and attenuation of hypersonic thermal acoustic phonons. A theory of Brillouin scattering from polymer blends is presented and illustrated qualitatively by several examples. The study of blend compatibility is illustrated for the system PMMA-PVFS. The detection of inhomogeneous additives is shown for commercial PVC film and cellulose acetate, and simultaneous measurements on separated phases are presented for Mylar film. The main purpose of the paper is to stimulate further work in a potentially promising field. 

Recently, Brillouin scattering has proved useful in this area for studying the frequency dependence of hypersonic (GHz zone) absorption and dispersion velocity in liquid sulphur dioxide [91] the effect of isotopes on hydrodynamic fluctuations in self-associated fluids [92] and the elastic properties of polyethylene glycol solutions in water, benzene and toluene [93]. 

Under hypersonic continuum flow conditions, a strong shock wave forms in front of the nose of the reentry vehicle. A typical reentry velocity at high altitude is 7 km/s (about Mach 25). The post-shock temperature for this Mach number, based on theoretical gas dynamics, is about 15 000 K and the peak temperature inside the shock is even higher (about 25 000 K). 

In Chap. 2, Raz and Levine investigate a regime of dynamics where the motion along intermolecular coordinates is comparable or faster than that of intramolecular vibrational modes. These conditions exist momentarily when a large cluster impacts a surface at hyperthermal velocities ( 10 kms ). In Chap. 3, Boyd describes the challenges facing a direct simulation Monte Carlo modeler of hypersonic flows in a regime intermediate to the continuum and free molecular flow limits. Many of the lessons... 

The mixture of TNT and RDX is named Composition A when compressed with a small amount of wax. The detonation velocity is approximately 8100 m/s. When TNT and RDX are cast together with a wax, the mixture is named Composition B. The mass fraction ratio is TNT/RDX = 0.4/0.6 with 0.1 % wax. The density is in the range 1600-1750 kg/m3 and the detonation velocity is about 8000 m/s. The melting point of TNT is 353.8 K, which is too low for its use in warhead charges under conditions of supersonic or hypersonic flight (Mach number > 5). Deformation of charges occurs because of the aerodynamic heating. 

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