- ItemOpen AccessCavitation damage scale effects: sudden enlargements(Colorado State University. Libraries, 1975) Stripling, Travis Earl, author; Tullis, J. Paul, advisor; Olson, H. G., committee member; Meroney, Robert N., committee member; Ball, James W., committee memberThe present study was aimed at investigating the cavitation damage downstream from sudden enlargement energy dissipators. Tests were conducted on geometrically similar circular orifices of five different orifice to pipe diameter ratios in three different pipe sizes of: 3-, 6-, and 12-inches. Highly polished 1100-0 aluminum specimens were mounted in the downstream pipe wall to detect the cavitation damage. Two different stages or levels of cavitation damage were defined for study: (1) "incipient damage" level based upon maintaining a maximum pitting rate of 1 pit/in.2/min. on 1100-0 aluminum, (2) cavitation damage regime where the maximum pitting rate was greater than 1 pit/in.2/min. Previously defined incipient damage scaling equations based upon damage data taken in the 3-in. pipe accurately predicted the incipient damage condition in the 6- and 12-in. pipes. Pressure scale effects on the incipient damage condition were constant for all pipe sizes tested. There were no size scale effects found for the incipient damage condition based upon maintaining a maximum pitting rate of 1 pit/in.2/min. The incipient damage condition was investigated in greater detail by studying the variation in the volume of the damage pits in the soft aluminum. The volume of the damage pit was related to the energy expended in format ion of the pit which was assumed to be a measure of the intensity of the cavitation impact blow forming the pit. It was found that at the incipient damage condition the intensity of cavitation impact blows varied with pipe size and orifice to pipe diameter ratio. The damage in the cavitation damage regime was found to be a function of both cavitation pitting rate and intensity of cavitation impact blows (energy of pit formation). A cavitation intensity parameter, defined as the product of cavitation pitting rate and energy of pit formation, was used to measure cavitation damage. Data was presented to show the general variation of cavitation intensity under conditions of varying cavitation index, varying upstream pressure, and varying pipe size. In addition, the cavitation damage scaling evaluations introduced by Thiruvengadam were used along with experimentally measured flow field data to predict variations in cavitation pitting rate and intensity of impact blows. The experimental results indicate that it is impossible to simulate total prototype cavitation loading conditions in terms of both cavitation pitting rate and intensity of impact blows in a hydraulic model of reduced size. An example is introduced demonstrating this fact. An alternative method using the cavitation intensity parameter is proposed for modeling prototype cavitation loading conditions in a model of reduced size.
- ItemOpen AccessFunction of the cecal microflora in sage grouse nutrition(Colorado State University. Libraries, 1968) Barber, Thomas Amos, author; Nagy, Julius G., advisor; Nagy, Julius G., advisor; Mayeux, Jerry V., committee member; Ryder, Ronald, committee member; Mayeux, Jerry V., committee member; Ryder, Ronald, committee memberAn investigation of the cecal bacteria of sage grouse (Centrocercus urophasianus) was undertaken in an effort to obtain information on the function of the cecal microflora in the nutrition of this species. The project included experiments in three main areas: (1) isolation and characterization of cecal bacteria; (2) gas chromatographic analysis of cecal contents for VFA produced by bacterial fermentation; (3) chemical analysis of sage grouse feed and droppings. Cultures of bacteria from the cecal contents of sage grouse showed a large bacterial population to be p re sent. Predominant organisms in cecal contents were similar to normal avian enteric types. Organisms resembling Actinomyces bifidus and a streptococcus-like form were the most numerous types in the ceca. Solid media including the supernate of centrifuged cecal contents ( CFAM) and clarified rumen fluid (RFAM) proved to be superior to all other media tested for total counts of cecal bacteria; the use of these media was a necessity for the culture of the two predominant types of cecal organisms. Total culture counts of cecal bacteria in winter-killed birds showed a mean of 18 X 109 organisms per gram of wet cecal contents as compared to 30 X 109 for those collected in summer. Only insignificant numbers of cellulose-digesting organisms were cultured despite use of several enrichment media. Large amounts of volatile fatty acids (VFA) were produced by the cecal microbial fermentations. Higher levels of VFA were present in ceca in winter when the birds were on total sagebrush leaf diets and lower total numbers of cecal bacteria were present. Analysis of cecal contents showed that they contained only about 3% fiber (of a 10-16% dry weight). The high concentration of fiber in rectal droppings accounts for nearly the total amount ingested in sagebrush leaves. Essential oils of sagebrush are present in greater amounts in the Type A-3 sagebrush leaves selected by the grouse examined as summer food. Crops of winter-killed birds contain a mixture of all three subtypes of sagebrush; total oil levels in the digestive tract at this season were higher than in the summer when forbs comprised a portion of the diet.
- ItemOpen AccessObservation of progressive convective interactions from the Rocky Mountain slopes to the Plains(Colorado State University. Libraries, 1979) Philipp, Ceri Burns, author; Vonder Haar, Thomas H., advisor; Cotton, William R., committee member; Meiman, James R., committee memberGeosynchronous satellite data were employed for a climatological study of two summers' data and for a specific case study to observe convective interactions between the eastern slopes of the Colorado Rocky Mountains and the plains of eastern Colorado and western Kansas. The climatological study involved imagery for May-August 1976 and 1977 for a study region defined from eastern Utah to western Kansas that was divided into five areas. Development and movement of convective activity from the mountains to the plains was identified by the satellite imagery analysis for 12% of the 1976 summer days (13 out of 108) and 17% of the 1977 summer days (16 out of 94). When precipitation records for stations in western Kansas were consulted, it was found that these satellite- identified development and movement days made a significant contribution to the monthly and seasonal total precipitation for this area. There were instances when the contribution was greater than 90% (for some months) and greater than 50% (for seasonal total). Further results from the climatological study showed that cumulus clouds were most likely to form in the southwestern and central Colorado mountains between 0700 and 1000 MDT (1300 to 1600 GMT). Mountain regions were generally clearing remnants of old cells during the late afternoon, evening and night hours with development and growth of new cells occurring in the early morning to early afternoon. Plains regions generally were clearing remnants during morning and early afternoon hours with convection developing in late afternoon, evening and night hours. A quantitative case study was performed for 4 August 1977 when 3-minute rapid scan satellite data were available. It was a day when optimum conditions for development and movement from the mountains to the plains existed. Computer programs on the All Digital Video Imaging System for Atmospheric Research (ADVISAR) were used to study changes in cloud size, cloud number, and cloud brightness for two areas in Colorado. The first area was in the northeastern Colorado Rocky Mountains where the primary storm system moved through. The second area was in southern Colorado (near Pueblo) which included both mountains and plains regions and primarily stationary convective activity. From the quantitative study, no definite correlation was found between changes in cloud number and changes in cloud brightness. Differences in both quantities over 3-minute intervals were found to be significant and were sometimes larger than 6 or 9-minute changes. Both areas showed varying patterns of increasing and decreasing cloud number and brightness. The first area with the active moving system tended to have greater mean brightness and more time periods with large clouds than the stationary system area. It also had larger "largest clouds" over the time period studied (1100 - 1624 MDT) than the second area.
- ItemOpen AccessA theoretical investigation of convective patterns in the lee of the Colorado Rockies(Colorado State University. Libraries, 1970-03) Dirks, Richard A., author; Reiter, Elmar R., advisor; Grant, Lewis, committee member; Gray, William, committee member; Morel-Seytoux, Hubert, committee memberThe western Great Plains are observed to be the formation region for many of the summer convective systems in the central United States. Convective activity is greatly reduced in the immediate lee of the Colorado and New Mexico Rockies while it is intensified about a hundred kilometers eastward. An explanation of these observed convective patterns is proposed on the basis of a regional scale Rocky Mountains-Great Plains circulation system. A two-dimensional numerical model of a large scale mountain-plain circulation is presented which includes the effect of a slightly sloping plain. The equations are integrated over periods of two to eight hours for various initial conditions of thermal stability and ambient wind. An increase in thermal stability is found to suppress the developing circulation while the circulation is enhanced by an ambient shearing wind. Typical observed stability and ambient wind fields yield an interacting two cell circulation with a strong cell over the mountain slope and a weaker cell over the plain. The resulting airflow is characterized by strong descent (m sec -1) in the immediate lee of the mountains and weak ascent (cm sec -1) in a broad region 100 to 300 km leeward. An investigation of contributing factors reveals the effect of the plain slope to be a primary cause of the ascending flow over the plain. The flow patterns which develop correspond well with observed diurnal oscillations in upper wind profiles over the plains with regard to velocity magnitude, time of reversal, and depth of flow. The dynamic effects of the circulation are found to be of sufficient magnitude to control convective activity. The spatial distribution of the dynamic effects is also in general agreement with observations of related convective activity. Nocturnal cooling reverses the circulation around "sunset" and results in ascending flow in the near lee of the mountains. This compares favorably with observed convective activity in that region. An examination of orographic waves and other plausible mechanisms finds that these are not generally applicable over the wide range of observed conditions. This restriction does not apply to the Rocky Mountains-Great Plains circulation system.
- ItemOpen AccessAtmospheric water balance of the Upper Colorado River Basin(Colorado State University. Libraries, 1968-01) Rasmussen, James L., author; Riehl, Herbert, advisor; Marlatt, William E., committee member; Dils, Robert E., committee memberThe atmospheric branch of the hydrologic cycle is investigated to determine the wintertime accumulation of water over the Upper Colorado River Basin. The parameter precipitation minus evaporation is computed as a residual from the atmospheric water balance equation. The study covers the seven winter seasons 1957 through 1963. The results show that the periods of evaporation as well as the periods of heavy precipitation determine the seasonal water balance of the basin. The seasonal course of daily evaporation rate is determined. The evaporation rate varies by a factor of two over the winter season. Further, a strong decay with time of evaporation rate is observed during the early and mid-winter months. A less pronounced decay is obtained during March and April. The basin precipitation data obtained from the atmospheric water balance computation are compared to a basin precipitation estimate independently obtained using data from fourteen rain gauges. The conclusion is reached that the gauge data underestimate the basin precipitation by about fifty per cent. Much of this bias is shown to be due to the lack of sampling over the high elevation regions where the precipitation is greatest. The wintertime accumulation of water over the basin is shown to be highly related to the April through March runoff from the basin. The relationship shows that the accumulated water is apportioned by a ratio of one to four between runoff and evaporation respectively. Finally the application of the atmospheric water balance computation to the problem of runoff forecasting is discussed.