Applied Scientific Research

The design curves for TE 01n dielectric cavity resonators, the quality factor, and the effective volume are computed from the characteristic equation of a hollow dielectric cylinder. A method for measuring relative values of the effective volume of different cavities is described. In an X-band electron spin resonance spectrometer the dielectric cavity gives a good signal to noise ratio. Advantages of the dielectric cavity resonator are described.

Agglomerate aerosols in a turbulent flow may be subjected to very high turbulent shear rates which through the generation of lift and drag can overcome the adhesive forces binding the constituents of an agglomerate together and cause it to break-up. This paper presents an analysis of the experimental measurements of the breakup of agglomerates between 0.1–10 μm in size, in a turbulent pipe flow followed by an expansion zone with a Reynolds numbers in the range 105 to 107. The analysis shows that even in wall bounded turbulence, the high turbulent shear stresses associated with the small scales of turbulence in the core can be the main source of breakup preceding any break-up that may occur by impaction at the wall. More importantly from these results, a computationally fast and efficient solution is obtained for the General Dynamic Equation (GDE) for agglomerate transport and breakup in highly turbulent flow. Furthermore the solution for the evolution of the aerosol size distribution is consistent with the experimental results. In the turbulent pipe flow section, the agglomerates are exposed continuously to turbulent shear stresses and experience more longer term breakup than in the expansion zone (following the pipe flow) where the exposure time is much less and break-up occurs instantaneously under the action of very high local turbulent shear stresses. The validity of certain approximations made in the model is considered. In particular, the inertia of the agglomerates characterised by a Stokes Number from 0.001 for the smallest particles up to 10 for 10 μm particles and the fluctuations of the turbulent shear stresses are important physical phenomena which are not accounted for in the model.

The coupled problem whereby a solid heat generating cylinder is being cooled in steady state by a coolant in potential flow is investigated. An analytical technique for determining the temperature distributions in the solid and the fluid is presented. Numerical studies for six Péclet numbers (0.9