Swirl diameter ratio

The data indicated that droplet-size changes are primarily influenced by injection pressure and orifice size while secondary changes can be attributed to fluid properties, orifice shape, and the nozzle s internal length diameter ratio. This last point was not observed by Dombrowski and Wolfsohn (8) for more conventional swirl spray nozzles. Nevertheless, they present a useful correlation between Sauter mean diameter and operating conditions. 

These partially overcome the weakness of the simplex pressure jet regarding turndown ratio by spilling back the unconsumed fuel at part load. In this way, the swirl velocity in the exit chamber is maintained constant but the diameter of the exit hole remains the same. A further... 

The enhancement of heat transfer inside a circular duct is often achieved by inserting a thin, metal tape in such a way that the tape is twisted about its longitudinal axis, as indicated in Fig. 5.47. Swirl flow is created in this manner. The width of the tape is usually the same as the internal diameter of the duct. The tape twist ratio XL is defined as H/d. When XL approaches infinity, the circular duct with the twisted tape becomes two semicircular straight ducts separated by the tape. 

Thep and q denote the integral exponents of D in the respective summations, and thereby explicidy define the diameter that is being used. ZV and Dt are the number and representative diameter of sampled drops in each size class i. For example, the arithmetic mean diameter, D10, is a simple average based on the diameters of all the individual droplets in the spray sample. The volume mean diameter, D3Q, is the diameter of a droplet whose volume, if multiplied by the total number of droplets, equals the total volume of the sample. The Sauter mean diameter, D32, is the diameter of a droplet whose ratio of volume-to-surface area is equal to that of the entire sample. This diameter is frequendy used because it permits quick estimation of the total liquid surface area available for a particular industrial process or combustion system. Typical values of D32 for pressure swirl atomizers range from 50 to 100 Jim. 

Petela and Zajdel [73] and Zajdel [74] conducted experiments on coal slimy atomization where coal particles of diameters up to 385 pm were mixed in a solution of benzoic acid and atomized using a swirl nozzle. The experiment by Petela and Zajdel [73] was conducted on monodispersed coal particles. In their experiment, 140 atomization processes were conducted however only 74 of them were used to derive the formula given. Zajdel [74] later ciuiducted a similar experiment using polydispersed coal particles. The resulting equations, 24.7.xiv and 24.7.XV, are shown in Table 24.7. An interesting aspect about both equations is that only ratios are cmisidered instead of individual variables. It should be noted... 

Diblock copolymers were synthesised by two stepwise anionic polymerisation methods. One method produced diblock copolymer plus 30% of poly(2-vinylpyridine) homopolymer. The copolymers were dissolved in O.IM hydrochloric acid. When the pH was increased by the dropwise addition of 0.1 M sodium hydroxide, micelles with well-defined hydrodynamic diameters formed spontaneously at around pH 5. Further basification produced stable micelle structures and reacidification produced the mirror image of this titration curve. Blue swirls were observed when sodium hydroxide was added at pH4 or pH5. The micelle sizes were measured by quasielastic light scattering. It is shown that (1) it is possible to control micelUsation by pH and (2) formation of well-behaved micelles of variable hydrodynamic diameter is possible by titration of different ratios and different total polymer concentrations of poly(2-vinylpyridine/poly(2-vinylpyridine-block-PEO). Relevance to drug release systems that can remain intact and circulate for long periods within the vascular system is suggested. 17 refs. 

The results of experiment No. 1 (hollow cone nozzle with attached swirl body) and No. 2 (removed swirl body) show that the swirl body does not affect the particle formation. The mean particle diameter ( io.s) as well as the Sauter mean diameter (SMD) are rather the same. The experiments No. 3 and No. 4 compare the atomization quality of a HCN without swirl body and a simple orifice. The orifice obviously can be used to generate powders which have particle size characteristics which are comparable to powders which are produced with a hoUow cone nozzle of the same diameter. In the experiments No. 5 and No. 6, the influence of the L/D ratio of a spray device on the particle size was investigated. On the first look, a higher L/D ratio might lead to bigger particles. 

The variation of measured mixing time with gas fiow rate for three different vessels are presented in Figs. 5.38,5.39 and 5.40. The straight line in each figure represents the best fit of the measured data for the same aspect ratio. The mixing time decreases with an increase in the gas flow rate, but increases with an increase in the bath diameter. The following empirical relation has been proposed for the mixing time in a bottom blown bath in the absence of swirl motion [52],... 

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