Hypersonic

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Plastics have found numerous uses in specialty areas such as hypersonic atmospheric flight and chemical propulsion exhaust systems. The particular plastic employed in these applications is based on the inherent properties of the plastics or the ability to combine it with another component material to obtain a balance of properties uncommon to either component. Some of the compositions and important properties of plastics are given in Tables 2-9 and 2-10 that have been developed over the years for use in flight vehicles and propulsion systems that are dependent upon chemical, mechanical, electrical, nuclear, and solar means for accelerating the working fluid by high temperatures. 

Since 1950, plastics have been development for uses in very high temperature environments. By 1954, it was demonstrated that plastic materials were suitable for thermally protecting structures during intense propulsion heating. This discovery, at that time, became one of the greatest achievements of modern times, because it essentially initially eliminated the thermal barrier to hypersonic atmospheric flight as well as many of the internal heating problems associated with chemical propulsion systems. 

Thermal protection The design of vehicles for hypersonic atmospheric flight represents a compromise between the intended... 

Nitrogen monoxide is used as an oxidizer in biproplnt systems with carbon monoxide or methanol-w as fuels, and it is added to N2O4 to advantageously modify the frp and bp of this oxidizer. It is also employed as a high enthalpy flow medium in hypersonic wind tunnels (Ref 10), and as an oxidizing gas in atomic absorption spectroscopy (Ref 12). Qf -19.7 kcal/mole (Ref 3)... 

Heckman, Behavior of Turbulent Scales in Hypersonic Sphere Wakes , Rept No DREV-R-696/73 Contract DAAH01-69-C-0921, ARPA Order — 133, Defence Res Est, Valcartier (Can) (1973) 42) Ya.L. Al pert, Waves and Satel-... 

To this date, the fabrication of structural ceramic composites has been limited to prototypes mostly in high-cost, high-performance aerospace applications such as missile guidance fins, hypersonic fuselage skins, inner flaps, and rocket nozzles. 

Hypersonic aircrafts and reentry vehicles such as Sanger, Hermes, Express, need reusable hot structures. Typical examples are nose cones, wing leading edges, winglets, flaps, rudders, shingles etc. 

Some prototype components are already under development. One of them is a ramp for the intake of the hypersonic propulsion system. This rather complex structure with dimensions of about 500 x 600 x 80 mm (in one piece) is planned to be tested under simulated thermal loads in early 1993. 

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. 

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. 

Tests were conducted using a scramjet combustor and the hypersonic facility of MAI equipped with kerosene-fueled preheater (vitiated air). Oxygen mass fraction T°02 in the vitiated air was slightly lower than in the atmospheric air. y°02 values for each test run can be found in Table 23.1. With an oxygen mass fraction in atmospheric air of 0.232, the kerosene equivalence ratio (ER) in vitiated air is determined by the following relation ... 

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. 

Figure 24.15 Single-sweep data traces of H2O absorption recorded in a hypersonic flow with an enthalpy of 10 MJ/kg. The panels shows the absorbance (as a function of laser frequency, cm ) near 1.400 pm (a) and 1.395 pm (6) recorded simultaneously. V = 4630T50 m/s Ttran.i = 561 15 K Ph20,i = 0.43 0.03 Torr Ttran,2 = 544 35 K and Ph20,2 = 0.45 0.06 Torr...

Brooks, S. B M. J. Lewis, and R. R. Dickerson, Nitric Oxide Emissions from the High-Temperature Viscous Boundary Layers of Hypersonic Aircraft within the Stratosphere, J. Geophys. Res., 98, 16755-16760 (1993). 

Tube to the Study of the Problems of Hypersonic Flight , JetPropulsion 26, 549-55 (July 1956) 8a) B.A. Thrush, PrRoySoc... 

Use of Fine Unheated Wires for Heat Transfer Measurements in the Shock Tube , GAL CIT Hypersonic Research Memorandum No. 55, (June I960) 16) Dunkle s Syllabus (1960-... 

Sargent Gross (Ref 11) reported the performance of a hypersonic ramjet having a detonation wave combustion process. 

Koecker (Ref 17) reviews specification requirements of fuels for industrial gas turbines, conventional jet turbines (kerosine gas oils), supersonic jet engines (JP-5 JP-6), and future hypersonic jets (endothermic fuels)... 

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