Nozzle geometry

Fig. 57. Entrance elongational strain rate (e ) calculated along the centerline of the flow tube for the different nozzle geometries (the origin of the abscissa is taken at the orifice entrance) (-----) abrupt contraction (-----) 14° conical inlet (---) 5° conical inlet...

Fig. 58. Degradation yield as a function of maximum entrance strain rate e(0) for different nozzle geometries (x) abrupt contraction with r0 = 0.175 mm (a) abrupt contraction with r0 = 0.25 mm (o) abrupt contraction with r0 = 0.34 mm ( ) abrupt contraction with r0 = 0.50 mm ( ) 14° conical inlet with r0 = 0.25 mm (a) 5° conical inlet with r0 = 0.25 mm...

Nguyen TQ, Kausch HH (1991) Influence of nozzle geometry on polystyrene degradation in transient elongation flow, to be published in Coll Polym Sci... 

Size Distribution of Atomized Droplets. The size distribution of droplets in a spray is a complex function of the properties of the liquid, the secondary gas (if used), and the nozzle geometry. The most reliable and often fastest way to determine this information is to experimentally measure the size distribution under the conditions of interest, and most nozzle manufacturers offer this service to their customers. 

Controlling variables in gas atomization of melts include nozzle geometry parameters and many process parameters. An exhaustive list of these parameters is given in Tables 2.12 and 2.13, respectively, along with typical values and/or ranges of the parameters. 

Derived from an analytical model for flat, infinitely thick liquid layer Effects of gas compressibility included Effects of gas/liquid ratio, liquid viscosity, and nozzle geometry not included X and Xm can be determined from the universal curves for metals in P29] for subsonic gas flow and in [330] for sonic/supersonic gas flow ... 

The first task was to produce carriers from different recipes and in different shapes as shown schematically in Fig. 8. The raw materials diatomaceous earth, water and various binders are mixed to a paste, which is subsequently extruded through a shaped nozzle and cut off to wet pellets. The wet pellets are finally dried and heated in a furnace in an oxidising atmosphere (calcination). The nozzle geometry determines the cross section of the pellet (cf. Fig. 3) and the pellet length is controlled by adjusting the cut-off device. Important parameters in the extrusion process are the dry matter content and the viscosity of the paste. The pore volume distribution of the carriers is measured by Hg porosimetry, in which the penetration of Hg into the pores of the carrier is measured as a function of applied pressure, and the surface area is measured by the BET method, which is based on adsorption of nitrogen on the carrier surface [1]. 

An important open question relates to whether an optimal AR exists with regard to entrainment enhancement. Laboratory jet experiments with pseudo-elliptical geometries [27] suggest that an optimal AR with regard to nozzle-geometry-enhanced entrainment might be at a value AR = 3. However, the experiments are not conclusive since they involved AR up to 3.5 and nonuniform momentum-thickness distributions, which are known to also affect the entrainment process [5]. Moreover, the possible effects on jet entrainment of other more complicated interactions such as vortex-ring bifurcation still need to be established. 

It is well known that in a jet flame blow-out occurs if the air-fuel mixture flow rate is increased beyond a certain limit. Figure 18.3 shows the relationship between the blow-out velocity and the equivalence ratio for a premixed flame. The variation of blow-out velocity is observed for three different cases. First, the suction collar surrounding the burner is removed and the burner baseline performance obtained. Next, the effect of a suction collar itself without suction flow is documented. These experiments show that for the nozzle geometry studied, the free jet flame (without the presence of the collar) blows out at relatively low exit velocities, e.g., 2.15 m/s at T = 1.46, whereas for > 2 flame lift-off occurs. When the collar is present without the counterflow, the flame is anchored to the collar rim and blows out with the velocity of 8.5 m/s at T = 4. Figure 18.4a shows the photograph of the premixed flame anchored to the collar rim. The collar appears to have an effect similar to a bluff-body flame stabilizer. The third... 

Haimovitch, Y., E. Gartenberg, A. S. Roberts, Jr., and G. B. Northam. 1997. Effects of internal nozzle geometry on compression-ramp mixing in supersonic flow. AIAA J. 35(4) 663-70. 

Specific impulse, calculated by this technique, represents a 100% conversion of chemical energy to mechanical energy, and, therefore, is an upper limit to the performance available from a real rocket engine. However, regardless of the technique utilized, the theoretical Is of each of the systems are compared on a common basis (e.g.y at the same combustion chamber pressure, nozzle geometry, exit pressure, etc.) with the desired performance level dictated by the mission and engine system rquirements. 

From Eq. (8.8) it is evident that particle momentum depending on mass and velocity of the particles is important to control the delivery. The particle acceleration and impact velocity are defined by particle properties such as size, density, and morphology and device properties such as pressure of the compressed gas source, nozzle geometry, and others. 

The SITEC nozzles consisting of a nozzle holder and exchangeable diamond nozzle pellets excellently fulfil all these requirements and thus allow a fast investigation of the influence of nozzle geometry on the product shape and size. 

It is clear that for operators the application rate of the pesticide, relevant meteorological conditions, liquid pressure at the nozzle, geometry of crop and application equipment are very important variables (van Hemmen, 1992a). Furthermore, work methods and hygienic measures taken by the operator (e.g. wearing of protective clothing) also affect exposure. 

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