Supersonic system

Figure 5-47. CO2 conversion degree into CO and O2 as function of preheating temperature in supersonic system of gas-dynamic stimulation of CO2 dissociation. Mach numbers (1) M=4.5 (eorrespondsto Tv/ro = 5) (2)M= 5.5 (corresponds to Tv/Jo = 7) (3)M= 6.5 (correspond to = 10) (4)...

Fig. 2.21. Schematic diagram of the SuperSonic system for couphng a high-temperature microbalance to a mass spectrometer. Reproduced by permission of Setaram, Caluire, France.

Using a mass spectrometer in molecular mode requires to work under very low pressures, in order to avoid any saturation of the quadrupole and to make the production of the electron beam easier. Using the supersonic system, it is necessary to have an important difference of pressure between the thermobalance and the mass spectrometer, in order to obtain a free molecular beam. 

On a technical point of view, the supersonic system is adjusted on the thermobalance furnace, in order to have the MS detector straight to the sample container (Fig. 2.40). 

As with most methods for studying ion-molecule kinetics and dynamics, numerous variations exist. For low-energy processes, the collision cell can be replaced with a molecular beam perpendicular to the ion beam [106]. This greatly reduces the thennal energy spread of the reactant neutral. Another approach for low energies is to use a merged beam [103]. In this system the supersonic expansion is aimed at the tluoat of the octopole, and the ions are passed tluough... 

Electronic transitions in molecules in supersonic jets may be investigated by intersecting the jet with a tunable dye laser in the region of molecular flow and observing the total fluorescence intensity. As the laser is tuned across the absorption band system a fluorescence excitation spectrum results which strongly resembles the absorption spectrum. The spectrum... 

The fluorescence excifafion spectra in Figures 9.47(a) and 9.47(b) show the Ojj bands of the A B2 X Ai system of aniline (see Figure 5.19) and the aniline Ar complex in a skimmed supersonic jet of aniline seeded into the argon carrier gas. 

More commonly, the resonant two-photon process in Figure 9.50(c) is employed. This necessitates the use of two lasers, one at a fixed wavenumber Vj and the other at a wavenumber V2 which is tunable. The first photon takes the molecule, which, again, is usually in a supersonic jet, to the zero-point vibrational level of an excited electronic state M. The wavenumber of the second photon is tuned across the M to band system while, in principle, the photoelectrons with zero kinetic energy are detected. In practice, however, this technique cannot easily distinguish between electrons which have zero kinetic energy (zero velocity) and those having almost zero kinetic energy, say about 0.1 meV... 

Because of tank heating, fuel volatiUty is also more critical in supersonic aircraft. For example, the Concorde tank is pressurized to prevent vapor losses which could be significant at high altitude where fuel vapor pressure may equal atmospheric pressure. The tank can reach 6.9 kPa (1 psi) at the end of a flight. The need to deoxygenate fuel for thermal stabiUty in the HSCT will doubdess require a similar pressurized system. 

Coppage, J.E. et al., Study of Supersonic Radial Compressors for Refrigeration and Pressurization Systems, WADC Technical Report 55-257, Astia Document No. AD 110467, 1956. 

The fact that gases have a simple equation of state makes possible the use of absorptiometry with polychromatic beams to give information about the state of a gas under conditions (in detonation waves,16 boundary layers,17 or supersonic flow18) transient or difficult of access. Temperature measurements19 have also been made. The technique is a unique method for studying the fluidization of a finely divided solid by a gas. Bed density profiles, which reveal the character and effectiveness of fluidization, have been readily determined20 without disturbing the system as probes would inevitably do. 

In a solid-propellant rocket motor, the propellant is contained within the wall of the combustion chamber, as shown in Fig. 1. This contrasts with liquid systems, where both the fuel and oxidizing components are stored in tanks external to the combustion chamber and are pumped or pressure-fed to the combustor. In hybrid systems, one component, usually the fuel, is contained in the combustion chamber, while the other component is fed to the chamber from a separate storage tank, as in liquid systems. The solid-propellant motor also has an ignition system located at one end to initiate operation of the rocket. The supersonic nozzle affects the conversion of... 

The several industrial applications reported in the hterature prove that the energy of supersonic flow can be successfully used as a tool to enhance the interfacial contacting and intensify mass transfer processes in multiphase reactor systems. However, more interest from academia and more generic research activities are needed in this fleld, in order to gain a deeper understanding of the interface creation under the supersonic wave conditions, to create rehable mathematical models of this phenomenon and to develop scale-up methodology for industrial devices. 

Recently, a revival of electron ionisation LC-MS has been proposed by development of LC-SMB-MS [529]. In this system, the LC output (50-250 p,Lmin 1) is vaporised at atmospheric pressure and expanded from a supersonic nozzle into the vacuum system... 

Detonations produce much higher pressures than what be considered ordinary explosions. In most cases a process vessel or piping systems will be unable to contain detonation pressure. The only safe procedure is to avoid process system detonations is to preventing the formation of flammable vapor and air mixtures within vessels and piping systems. While the flame speed of explosions is at relatively slow speed, detonations travel at supersonic speeds and will be more destructive. 

An intelligent process diagnostics and control system has been integrated for supersonic inert gas metal atomization (SIGMA) at the National Institute of Standards and Technology (NIST) in the... 

As became obvious in the preceding section, progress in understanding alcohol clusters very much depends on the ability to generate these clusters in supersonic jet expansions or in other variants of low temperature isolation and to detect their dynamics via spectroscopic methods. Therefore, some important spectroscopic tools employed in this field shall be summarized, with focus on the alcoholic systems that have been addressed by them. Solution [22, 26, 141, 142] and supercritical [24 26] state techniques will not be covered systematically. 

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