Interference effects during burning in air for stationary n-heptane, ethyl alcohol, and methyl alcohol droplets

Experiments have been conducted for the determination of the evaporation constant and flame shapes of two and of five closely spaced droplets burning in air. Droplets of approximately the same and of different diameters were used at various distances between the droplet centers. The apparent flame shape, which was observed only for n-heptane droplets, changes very little during burning. The square of the droplet diameter decreases linearly with time for fixed spacing between droplet centers, at least within the experimental limits of accuracy. In general, the average evaporation constant for two droplets, K', must be assumed either to vary continuously during burning or else to be a function of average initial drop diameter, D^0. The change of K' with time corresponds to the second derivative in plots of the square of the diameter vs. time. These second derivatives are not defined in our work because of unavoidable scatter of the experimental data. Attempts at understanding the observed results by considering published theories for single droplets, as well as groupings obtained from dimensional analysis, have been unsuccessful. It appears that the diffusion model for the heterogeneous burning of single fuel droplets will require serious revision and extension before the burning of droplets arrays and sprays can be understood quantitatively. Furthermore, the effective value of K' for a spray probably depends not only on the fuel-oxidizer system but also on the injection pattern. For this reason additional studies had best be carried out under conditions corresponding to those existing in service models

Lawyer as Policy Maker

This convocation address was given to the charter class of the BYU Law School on April 23, 1976

MOLE AND WOODRAT CONTROL

MOLES: In regions where moles thrive, lawns in golf courses, parks, cemeteries and home yards are often made unsightly by dirt mounds and ridges pushed up by the active little animals. In cultivated land, moles may cause consider¬able economic loss through their burrowings. Mole control can be divided into six basic categories: exclusion, repellents, gases, toxic baits, reduction of food supply, and trapping. Un¬changed over the years, trapping is still considered the most reliable of all methods of control, however, under certain conditions or situations, the other methods of control may be extremely useful. WOOD RATS: The native wood rat (genus Neotoma), also locally named pack rat, trade rat, mountain rat, brush rat and cave rat, is the typical rat in most respects resembling, superficially, the common house rat. The habits of all species of wood rats are in general very similar, differing in details according to regions and local environments. Wood rats do not frequent towns or cities as do their cousins the Norway rat, but often live in the vicinity of farmhouses, mountain cabins or summer homes and occasionally become a nuisance by invading dwellings and other buildings to construct nests or search for food. The animals are also known to carry plague and are suspected of carrying other diseases of public health significance. Though not often injurious to crops and agricultural enterprises, occasionally they become numerous enough to do limited damage to crops in fields and gardens. In some regions they have been known to inflict injury to orchard trees. Valuable nut crops are sometimes carried off by the rodents. In the northwest portion of California some damage has been attributed to wood rats in young timber plantings. Compared to other devastating rodents of California, the wood rat ranks as a pest of minor importance. Troublesome wood rats may be out witted or discouraged through exclusion, destruction of dens, or the use of repellents. Population reduction, when necessary, is most often accomplished by trapping or by using toxic baits