Pulse with rotary valve

Figure 23.3 shows a pulse combustor with rotary valves, which is a modification of membrane combustors (Smucerowicz, 1999). It consists of two valve plates with identical orifices. One plate is static, while the other one rotates. The air flows into the combustion chamber when slots in the two plates overlap otherwise, the valve is closed. The rotation of the valves has to fix the oscillations frequency. The valves must be open when underpressure occurs in the chamber to get engine into acoustic resonance. 

Figure 14.4 Design principle of pulse combustor with rotary valve. (From Lock-wood, 1987.)...

A precision injection device is required to minimize sample dispersion and keep the sample volume and length of sample zone reproducible. This is normally a rotary valve similar to that used for injection in HPLC. Exact timing from sample injection to detection is critical because of rapidly occurring reactions which are monitored before they reach completion. This demands a constant flow rate with low amplitude pulsing, normally achieved by a peristaltic... 

Figure 14.13. Towers with reciprocating trays or with pulsing action, (a) Assembly of a 36 in. Karr reciprocating tray column (Chem. Pro. Co.), (b) Sieve trays used in reciprocating trays columns (left) large opening trays for the Karr column (middle) countermotion trays with cutouts (right) countermotion trays with downpipes for heavy phase, (c) Rotary valve pulsator, consisting of a variable speed pump and a rotary valve that alternately links the column with pairs of suction and discharge vessels, (d) Sieve tray tower with a pneumatic pulser [Proc. Int. Solv. Extr. Conf. 2, 1571 (1974)]. (e) A pulser with a cam-operated bellows.

Based on the manner in which fuel and air charge the combustion chamber, pulse combustors are divided into two general categories those with mechanical valves and those with aerodynamic valves (also called valveless combustors). Mechanical valves can be further divided into three types flapper valves, reed valves, and rotary valves. 

According to Kentfield (1993), a pulse combustor is a combustion-driven device with self-aspirating feature, and this effect is achieved as a consequence of the internal unsteady flow events. In contrast, a pulsed combustor is a device with cyclic but nonresonant combustion as dictated by wave events. Pulsed combustors usually operate at a much lower than natural frequency, often controlled by an ignition, fuel injection, or a valve sequence. Therefore, valveless or flapper valve combustors fall into category of pulse combustors while mechanically driven valves (e.g., rotary valve) used to control either air or fuel inflow, flue gas outflow, or both should be categorized as pulsed combustors, unless the operation of a mechanical valve is controlled by resonant phenomena in a feedback mode. Such a design is known as a frequency-tunable pulse combustor. 

The frequency-tunable pulse combustor consists of a tube comprised of a combustion zone and an exhaust zone. It is within the combustion zone that the reaction between fuel and air occurs, causing heat to be released and thereby exciting an acoustic wave in the combustor. Separate air and fuel inlets are present to supply the combustion zone with the necessary reactants. Rotary valves are used in the Sonotech system to control fuel and airflows into the combustion chamber (Lockwood, 1987). The resulting hot combustion gases are freely exhausted from the combustor. 

Fig. 2.17. Side elevation of the vacuum setup of the molecular beam machine. Chi vacuum chamber to generate the molecular beam by adiabatic expansion. The oven shown in Fig. 2.19 is inside. Ch2 vacuum chamber where the molecules interact with the laser pulses and are detected by a quadrupole mass spectrometer (QMS) or a Langmuir-Taylor detector (Fig. 2.22). Chi is pumped by an oil diffusion pump (DP) with a cold trap (CT), Ch2 by a turbomolecular pump (TP). Prevacuum is provided by a Roots (RVP) and a rotary valve vacuum pump (RVVP)...

Fig. 1.1. Details of the high-frequency iaser evaporation source. Shown are the rotary motor, which drives the planetary gear assembly for turning the target, and the thermalization chamber with exchangeable expansion nozzie. The iaser-produced plasma expands into this thermalization chamber. A heiium gas puise is then introduced by a piezo-driven pulsed valve and synchronized with the iaser puise into the same volume. The metal-gas mixture then expands through the nozzie into the vacuum leading to cluster formation. In contrast to conventional sources, the laser beam is coaxial to the molecular beam axis. The bellow is used to aiign the source along the optical axis of the ion optics...

DuPont Series 848 Amplifier Pump at 4500 p.s.i. with no pulse dampener. A six-port Rheodyne rotary injection valve fitted with a 200-fil loop was mounted between the pump and the column Column... 

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