Cavity growth rate

As discussed in the previous section, excited shear layers dispersed at a higher rate than the natural shear layer growth rate. The amount of increase depended on the excitation frequency and amplitude. It was difficult to assess the effect of amplitude due to the passive nature of the excitation technique, but the frequency effect was investigated by comparing the results obtained with various cavities [14]. The results will be discussed in this section along with two other issues. One deals with the compressibility effect such as extending the results to a higher convective Mach number and the other concerned with possible thrust penalty associated with the passive excitation method. 

Figure 29.9 Normalized growth rate vs. convective Mach number for natural and excited shear layers 1 — [8] 2 — [9] 3 — [19] 4 — [18] 5 [20] 6 — present facility (natural) and 7 — excited with cavity acoustics...

Penetration of both types of cavity into the silicon nitride grains, as shown in Fig. 4.14, suggests that cavity growth occurs by the diffusion of silicon nitride from the cavity surface to the grain boundary. The transition between the two types of cavity can be rationalized by the Chuang theory of cavity growth,96 which relates the mode of cavity growth to the relative diffusion rate... 

In the above discussion it is assumed that the volume displaced from the cavity by diffusion is the sole contribution to the creep rate. However, an additional elastic displacement associated with cavities also contributes to the creep rate. This form of cavitation creep is important in fibrous composites, in which crack-like cavities propagate along the fiber interface. Termed elastic creep, this type of creep was first analyzed by Venkateswaran and Hasselman112 and later by Suresh and Brickenbrough.113 As with other forms of cavitation, both the nucleation rate and the growth rate are important. From Venkateswaran and Hasselman, the creep rate, e, for a body containing penny-shaped cavities distributed throughout the volume is... 

Figure 6.4.5 Growth rate profiles obtained in the macrocavity reactor at various temperauires. Solid curves were obtained trom the model containing gas-phase reaction and deposition on the surface. Film thickness is normalized by value at inlet of the cavity. (Adapted from K. VVatanabe and H. Komiyama, Micro/Macrocavity Method Applied to the Studs of the Step Coverage Formation Mechanism of SiOi Films by LFCVD." J. Electmehem. Soc.. 137 (1990) 1222, with permission of the Electrochemical Society. Inc.)...

B. Growth Rate of CdS Nanoparticles in Inner Cavities of Lipid Vesicles... 

Apparently, the nature of the rate-controlling step in CdS formation in the inner cavities of the vesicles is quite complicated and, probably, includes the preliminary formation of complexes of the anions with either some molecules in the lipid membrane or the CdS precursors (because the growth rate of the nanoparticles depends on the nature of the CdS precursors). 

The analyses shows that thermodynamic driving impetus influence on rate of hydrate formation, the ability of stabilizing large cavity of hydrate structure also has important effect on hydrate growth rate. Understanding from the angle of hydrate stability, the ratio(S) of object diameter and the cavity diameter can estimate the stability of cavity. In Table 4,... 

---