Mach surfaces

The first commercial supersonic transport, the Concorde, operates on Jet A1 kerosene but produces unacceptable noise and exhaust emissions. Moreover, it is limited in capacity to 100 passengers and to about 3000 miles in range. At supersonic speed of Mach 2, the surfaces of the aircraft are heated by ram air. These surfaces can raise the temperature of fuel held in the tanks to 80 °C. Since fuel is the coolant for airframe and engine subsystems, fuel to the engine can reach 150°C (26). An HSCT operated at Mach 3 would place much greater thermal stress on fuel. To minimize the formation of thermal oxidation deposits, it is likely that fuel deflvered to the HSCT would have to be deoxygenated. 

Lauf-flache, /. bearing surface (Mach.) journal (of tires) tread, -gewicht, n. sliding weight, -glasur, /. (Ceram.) flow glaze, -gummi, n. tread (of a rubber tire). 

Figure 7-44 shows the sequence of events involved in diffraction of a blast vave about a circular cylinder (Bishop and Rowe 1967). In these figures the shock fronts are sho m as thick lines and their direction of movement by arrows normal to the shock front. In Figure 1.13a, the incident shock 1 and reflected shock are joined to the cylinder surface by a Mach stem M. R is now much weaker and is omitted in succeeding figures. 

Mach Stem. A shock wave or front formed above the surface of the earth by the fusion of direct and reflected shock waves resulting from an airburst. Also called mach wave and mach front... 

Turner et al. (2004) studied the independent variables relative surface roughness, Knudsen number and Mach number and their influence on the friction factor. The micro-channels were etched into silicon wafers, capped with glass, with hydraulic diameters between 5 and 96 pm. Their surface roughness was 0.002 < ks< 0.06 pm for the smooth channels, and 0.33 < / < 1 -6 pm for the glass-capped ones. The surface roughness of the glass micro-channels was measured to be in the range 0.0014 [Pg.39]

The influence of compressibility was assessed by varying the Mach number in the range 0 < Ma < 0.38, while Kn and ks/H were kept low. Friction factor data were reported only with Ma < 1 at the exit, to ensure the flow rate was controlled by viscous forces alone. A mild increase in the friction factor (8%) was observed as Ma approached 0.38. This effect was verified independently by numerical analysis for the same conditions as in the experiment. The range of relative surface roughness tested was 0.001 < ka/H < 0.06, yet there was no significant influence on the friction factor for laminar gas flow. 

Stoebe T, Mach P, Grantz S, Huang CC (1996) Phys Rev E 53 1662. In this work the surface tension of the free standing films of some perfluorinated compounds has been measured. The intermediate value of the surface tension (=14 dyn/cm) between that of pure close-packed CF3 and CH3 groups indicates that the surface of the film consist of nearly equal proportions of these fragments... 

Here we will discuss in more detail the 10 Mach-Zehnder interferometer7. It is a nice vehicle for illustrating in what way the problem of looking for extremely high resolutions can be approached, an approach which appeared to be very successful. We will focus on the MZI used for bulk sensing and we will make some additional remarks on its utilization in surface sensing. 

Fig. 9.11 The calculated response of a 1.5 mm long silicon PWEF sensor in a Mach Zehnder interferometer configuration, as a film of final thickness d 2 nm and index n 1.5 grows on the waveguide surface. The normalized fractional surface coverage is also shown...

Fig. 9.14 (a) The measured variation of the Mach Zehnder interferometer (MZI) output intensity as a monolayer of streptavidin is bound to the surface, and (b) the optical phase change calculated from this intensity data... 

In a supersonic gas flow, the convective heat transfer coefficient is not only a function of the Reynolds and Prandtl numbers, but also depends on the droplet surface temperature and the Mach number (compressibility of gas). 154 156 However, the effects of the surface temperature and the Mach number may be substantially eliminated if all properties are evaluated at a film temperature defined in Ref. 623. Thus, the convective heat transfer coefficient may still be estimated using the experimental correlation proposed by Ranz and Marshall 505 with appropriate modifications to account for various effects such as turbulence,[587] droplet oscillation and distortion,[5851 and droplet vaporization and mass transfer. 555 It has been demonstrated 1561 that using the modified Newton s law of cooling and evaluating the heat transfer coefficient at the film temperature allow numerical calculations of droplet cooling and solidification histories in both subsonic and supersonic gas flows in the spray. 

Fig. 12.1 An ultra-fast heating of a cluster containing both N2 and 02 molecules upon impact at a surface. [9] Shown is the instantaneous configuration of 14 N atoms (dark) and 14 O atoms (light) 50 fsec after a cluster of 7 N2 and 7 02 molecules embedded in 97 Ne atoms impacts a surface at a velocity of 20 Mach. The potential used allows for alii 25 atoms of the cluster to interact with one another and with the atoms of the surface. In addition, each atom-atom chemical interaction is influenced by the presence or absence of other open-shell atoms nearby.

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