Droplet Injection

As discussed earlier, the particle/droplet dynamics can be significantly modified by timing the fuel injection to be in- or out-of-phase with the large-scale vortex structures. To explore if timed fuel injection could alter the stability characteristics, the flow was forced at the quarter-wave mode of the inlet and droplet injection was timed to be in- or out-of-phase with the forcing. Results from these simulations show that the pressure fluctuations at the quarter-wave mode of the inlet can indeed be amplified or attenuated depending on the phasing of the droplet injection. 

The vaporization rates and drag coefficients for 2,2,4-trimethylpentane (iso-octane) sprays in turbulent air streams were determined experimentally by Ingebo (40), who reported that the effect of relative velocity on the evaporation rate was represented by the 0.6 power of the Reynolds number and that the drag coefficient varied inversely with the relative velocity of the drops in the spray. By assuming that the evaporation rate was independent of velocity and the drag coefficient for droplets obeyed Stokes s law, the present author derived a mathematical theory for the ballistics of droplets injected into an air stream for which the velocity varied linearly with distance (57) and... 

Material associated with oil Dose Cured/Total Percent droplets injected into tumorsa (pg) cured... 

The droplet injection was initiated by energizing the electrode nearest the injector [99], By dielectrophoretic forces, fluid is drawn out of the pipet and forms a droplet, which then moves to the edge of the electrode. The dielectrophoretic forces have to be balanced properly with the interfacial tension forces to give uniformly sized droplets. 18 pm (3 pi) sized droplets for example, were made in that way. 

The reactor 07) consists of 5 by 28 cm flat flame burner downfired into a chimney of similar dimensions, fitted with Vycor windows for optical access. Access ports for droplet injection and sample probing are provided. As illustrated in Figure 3, fuel droplets are normally injected ballistically across the face of the burner. 

The soot temperature was found to exceed the gas temperature as measured by thermocouples in the absence of droplet injection but decayed at a similar rate. This is attributed to bulk heating effects associated with the localized burning of vaporized material. A detailed diffusion flame calculation for a cylindrical source of reactants and relative velocity on the same order as these experimental data, indicate that this bulk heating effect is reasonable. 

Let us consider experimental results obtained for an ethanol-C02 exchange. Figure 14a shows CO2 bubbles injected into pure ethanol solvent. Compared with ethanol droplets injected into pure CO2 under the same conditions (Figure 4a), the mass transfer is much more intense, and the concentration gradients are greater than those for a relatively slow evaporation of ethanol drops into the supercritical phase. In fact, this process is so intense that deformation and surface instability of the bubbles are clearly visible in... 

Figure 6.1 Schematic diagram of the shock tube with test section, droplet injection mechanism, and recording devices 1 — droplet generator 2 — high-speed pressure transducers 3 — low-speed pressure transducer 4 — vacuum port 5 — thermocouples 6 — diaphragm chamber bleed 7 — low-speed pressure transducer S — thermocouple and 9 — helium input and low-speed pressure transducer.

The source of the aerosol salt is the ocean. The elemental constituents occur in ratios which differ somewhat from those found in sea water. The chemical composition of the aerosol salt is influenced by several factors. When the salt aerosol is created at the sea surface by whitecaps, we And ion fractionation. That is, the sea water droplets injected into the atmosphere contain the elements in proportions different from those in sea water. Examples include different ratios for the halogens, alkali metals, sulfate, phosphate, and nitrogen (12, 44, 51, 62, 63), The causes for fractionation, both as physical and organic chemical processes are under... 

In this way, totally 200 different droplet injections are simultaneously embedded in the domain. 

FIGURE 10.21 Drying kinetics of droplets injected along stream 1. Droplet initial diameters are as indicated, (a, b) Particle surface temperatures (c, d) particle moisture contents. 

The procedure begins with droplets injection right from the nozzle with the diameter equal to the splash plate nozzle diameter. The injected droplets hit the splash plate and break into several smaller droplets. Figure 31.8 shows side view of the splash plate atomizer at the time of injection. Each droplet at any specific trajectory has a specific velocity and size, equal to the sheet thickness and velocity at that trajectory (i.e., azimuthal angle). The model intends to substitute the smooth fluid sheet on the plate with discretized droplets having the same diameter (thickness) and velocity as the sheet. While droplets move further downstream, they interact with the surrounding gas and each other. Droplets will break, coalesce. 

Dispensing Drop Droplet break up Droplet ejection Droplet formation Droplet generation Droplet injection Droplet release Droplet tear-off Droplet... 

The volume of the formed droplets injected into a carrier liquid can be lower than the volume of a sphere with a diameter of the main channel, if high shear forces (high flow rate of carrier liquid) and a small diameter of the nozzle are applied. Small droplets relaxing into a nearly ideal spherical shape are delivered in this case. They can be small and move through the channel like solid particles. The size of these particles increases with increasing diameter of the nozzle aperture and decreasing flow rate of the carrier liquid. 

Scrubber Water droplets injected into fine gas particles adhere to droplets which are then separated from the gas (typically by cyclones) Can achieve capture efficiencies of >99% [262] Low capital cost Can capture much smaller particles (sub-micrometre) than cyclone alone Useful for removal of hygroscopic or sticky particles and gas streams with high moisture contents Pumping cost can be significant, particularly for large flows Requires subsequent separation of particles from water... 

Drop Droplet Dispensing Droplet ejection Droplet injection Droplet generation Droplet formation Droplet release Droplet break up Droplet tear-off... 

Fig. 2.18 Changes of moisture content of droplets injected into the chamber at different points of time between 0.254 and 0.259 s.

In the FFA process, the droplets are injected at the central axis of the atomizer. To avoid the influence of entrainment, the droplet injection position is located below the entrainment region (Note In experiments the entrainment caused by secondary gas flow is eliminated by coupling primary gas flow). The mass median diameter (MMD, rfso.a) of the initial primary droplets is derived by the correlation in Rao and Mehrotra [24] ... 

In the PSGA process, the selected ring-gas nozzle typically is composed of 20 circular inlets. The axis of the circular inlet is parallel to the centre line of the atomizer, that is the inclination angle is 0°. The diameter of each inlet at the nozzle exit section is 1.1 mm. Figure 18.20 presents the calculated gas velocity distributions without droplet injection under different atomization pressures (po)-... 

Figure 7.8 Microreactor channel design with droplet jet injector, (a) Channel schematic showing dimensions, (b) Optical micrograph of droplet injection cross, (c), (d) Cross-sectional view of the channel, (e) Side view of the channel. (Reproduced form Ref [99].)...

Figure 7 CFD-DEM time series for spout fluidized bed simulations with droplet injections. Due to collisions between solid particles and droplets, the particles grow in size.

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