Nozzle velocity

Fig. 5. Effects of nozzle velocity on flame appearance in laminar and tuibulent flow (a), flame appearance (b), flame height and break-point height (40).

This is a low value, therefore, the possibility exists of an up-rate relative to any nozzle flow limits. At this point, a comment or two is in order. There is a rule of thumb that sets inlet nozzle velocity limit at approximately 100 fps. But because the gases used in the examples have relatively high acoustic velocities, they will help illustrate how this limit may be extended. Regardless of the method being used to extend the velocity, a value of 150 fps should be considered maximum. When the sonic velocity of a gas is relatively low, the method used in this example may dictate a velocity for the inlet nozzle of less than 100 fps. The pressure drop due to velocity head loss of the original design is calculated as follows ... 

Nomenclature axial, 226 centrifugal, 192 Non-perfect gas. t i Nozzle velocity, id Nozzles, axial compicssnr, fitting prchlciiis, 2-i"... 

Use 4-in. nozzle, velocity = 4.79 ft/sec (Cameron Table, Fluid Flow Chapter) Liquid Freon-12 in ... 

Another source of pressure drop will be the flow expansion and contraction at the exchanger inlet and outlet nozzles. This can be estimated by adding one velocity head for the inlet and 0.5 for the outlet, based on the nozzle velocities. 

Simulations are then performed for gas bubbles emerging from a single nozzle with 0.4 cm I.D. at an average nozzle velocity of lOcm/s. The experimental measurements of inlet gas injection velocity in the nozzle using an FMA3306 gas flow meter reveals an inlet velocity fluctuation of 3-15% of the mean inlet velocity. A fluctuation of 10% is imposed on the gas velocity for the nozzle to represent the fluctuating nature of the inlet gas velocities. The initial velocity of the liquid is set as zero. An inflow condition and an outflow condition are assumed for the bottom wall and the top walls, respectively, with the free-slip boundary condition for the side walls. 

From experiments, equations have been derived that enable calculation of the minimum velocity in the nozzle, the nozzle velocity, and the Sauter diameter at the drop size minimum. They provide the basis for the correct design of a sieve tray [3,4]. Figure 9.4a shows the geometric design of sieve trays and their arrangement in an extraction column. Let us again consider toluene-phenol-water as the liquid system. The water continuous phase flows across the tray and down to the lower tray through a downcomer. The toluene must coalesce into a continuous layer below each tray and reaches... 

For nozzle velocities above the slow-formation range but less than 30 cm./sec., Hayworth and Treybal (H8) accounted for the kinetic energy due to nozzle velocity. Their force balance (written in the form of an equivalent-volume balance) stated that the total volume (Vt) would be equal to the volume (7 ) necessary to overcome interfacial tension, plus the volume (7 ) necessary to produce a rising velocity at least equal to the nozzle velocity, plus a negative volume (Vk) equivalent of the kinetic energy supplied by the stream from the nozzle, thus... 

Continuous discharge of solids, as a slurry, is achieved by sloping the inner walls of the bowl toward a peripheral zone containing between 8—24 orifices, commonly called nozzles, as shown in Figure 14g—i. The nozzles must be spaced closely enough so that the natural angle of repose of the solids deposited between the nozzles does not cause a buildup of cake to reach into the disk stack and interfere with clarification. The size of the nozzles is limited because the fluid pressure at the wall, which can be 6.9—13.8 MPa (1000—2000 psi), produces high nozzle velocities (see eq. 30). On the other hand,... 

Calculate the pressure drop for the conditions of Example 7.20. Assume that the nozzle velocities are 5 ft/s (1.52 m/s), that the fluid density is 55 lb/ft3 (881 kg/m3), and that there are 24 baffles. Assume that there is also an impingement plate at the inlet nozzle. Calculate the pressure drop for both fouled and clean conditions. 

If the jet nozzle velocity is too low, and the liquid coming from it is much different in density from the liquid in the tank, it is possible to get stratification instead of good mixing. The minimum velocity can be estimated from fluid properties and vessel geometry, by the relation... 

The reported study on gas-liquid interphase mass transfer for upward cocurrent gas-liquid flow is fairly extensive. Mashelkar and Sharma19 examined the gas-liquid mass-transfer coefficient (both gas side and liquid side) and effective interfacial area for cocurrent upflow through 6.6-, 10-, and 20-cm columns packed with a variety of packings. The absorption of carbon dioxide in a variety of electrolytic and ronelectrolytic solutions was measured. The results showed that the introduction of gas at high nozzle velocities (>20,000 cm s ) resulted in a substantial increase in the overall mass-transfer coefficient. Packed bubble-columns gave some improvement in the mass-transfer characteristics over those in an unpacked bubble-column, particularly at lower superficial gas velocities. The value of the effective interfacial area decreased very significantly when there was a substantial decrease in the superficial gas velocity as the gas traversed the column. The volumetric gas-liquid mass-transfer coefficient increased with the superficial gas velocity. 

Particles of interest to wafer cleaning are small with respect to typical hydrodynamic boundary layers which can be as thick as a few tenths of a millimeter so the drag force actually exerted on the particle is that of a much slower moving fluid than the nozzle velocity of the jet. While more effective for small particles than brush scrubbing, the pressure required for submicrometer particle removal is too high for patterned wafer application. 

The physical entrainment rate of gas varies over orders of magnitude as a function of jet stability, which acts as the surface shape generator. The controllable parameters of the system are nozzle geometry, nozzle velocity, nozzle height, jet length, and jet velocity. McCarthy et al. (Ml) have analyzed gas entrainment in such contactors in terms of the surface roughness of the jet and have proposed an entrainment ratio ... 

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