Investigation of the influence of a step change in surface roughness on turbulent heat transfer

The use is studied of smooth heat flux gages on the otherwise very rough SSME fuel pump turbine blades. To gain insights into behavior of such installations, fluid mechanics and heat transfer data were collected and are reported for a turbulent boundary layer over a surface with a step change from a rough surface to a smooth surface. The first 0.9 m length of the flat plate test surface was roughened with 1.27 mm hemispheres in a staggered, uniform array spaced 2 base diameters apart. The remaining 1.5 m length was smooth. The effect of the alignment of the smooth surface with respect to the rough surface was also studied by conducting experiments with the smooth surface aligned with the bases or alternatively with the crests of the roughness elements. Stanton number distributions, skin friction distributions, and boundary layer profiles of temperature and velocity are reported and are compared to previous data for both all rough and all smooth wall cases. The experiments show that the step change from rough to smooth has a dramatic effect on the convective heat transfer. It is concluded that use of smooth heat flux gages on otherwise rough surfaces could cause large errors

Economic Analysis of Water Conservation Policies in the Texas Panhandle

Due to declining water availability from the Ogallala Aquifer, management policy alternatives for extending the life of the aquifer to sustain rural economies in the Texas Panhandle are evaluated. The study concludes that water conservation policies for the region significantly impact crop mix, resource usage, and net present value of farm profits over a sixty-year planning horizon.Ogallala Aquifer, Groundwater Conservation, Water Management Policy, Texas Panhandle, Resource /Energy Economics and Policy,

SLOW RECOVERY IN A MOUNT WASHINGTON, NEW HAMPSHIRE, ALPINE PLANT COMMUNITY FOUR YEARS AFTER DISTURBANCE

Four years after a trench was dug through alpine habitat on Mount Washington, New Hampshire, we surveyed vascular plants, bryophytes, and lichens in the disturbed area, analyzing species richness and abundance compared with values in adjacent, undisturbed areas. Plants had begun recolonizing the disturbed area, but species richness and abundance remained far lower than in the undisturbed community. Among vascular plants, graminoids colonized most quickly, and woody species were largely absent. Species with the highest frequency and greatest abundance in the disturbed area also were common and abundant in the undisturbed community. Bryophytes appeared to be colonizing no more quickly than vascular plants. Treeline and elevation exerted separate effects on community structure and recovery. Treeline influenced species richness, abundance, and the rate of recovery of vascular plants, but there was no evidence of an additional effect of elevation either above or below treeline. Treeline also influenced species richness of bryophytes and lichens. In addition, elevation appeared to have a separate effect on their rate of recovery in alpine habitat: species richness of bryophytes and lichens declined with elevation in the disturbed community but not in the undisturbed community. This suggests that elevation has a transient effect on colonization and/or survival, but only above treeline. In general, recovery has occurred more quickly below treeline. This survey establishes baseline information that will be useful in assessing the rate of recovery after future surveys