Results are presented from an experimental investigation of a linear, supersonic compressor cascade tested in the supersonic cascade wind tunnel facility at the DFVLR in Cologne, Federal Republic of Germany. The cascade was derived from the near-tip section of a high-throughflow axial flow compressor rotor and has a design relative inlet Mach number of 1.61. Test data were obtained over the range of inlet Mach numbers from 1.30 to 1.17. Side-wall boundary layer suction was used to reduce secondary flow effects within the blade passages and to control the axial-velocity-density ratio (AVDR). Flow velocity measurements showing the wave pattern in the entrance region were obtained with a laser anemometer. The unique-incidence relationship for this cascade, relating the supersonic inlet Mach number to the inlet flow direction, is discussed. The influence of static pressure ratio and AVDR on the blade performance is described, and an empirical correlation is used to show the influence of these (independent) parameters for fixed inlet conditions on the exit flow direction and the total-pressure losses.
As a sequel to an earlier study of the stochastic properties of daily rainfall occurrence in a summer thunderstorm season, the probabilistic nature of daily rainfall depths is examined. Daily rainfall depths are found to be well described by what may be termed a compound exponential distribution. Some 1600 to over 2000 daily rainfalls from three stations are partitioned in various conceptual ways to evaluate homogeneity with respect to the pattern of occurrence with sequences or seasons as well as the annual variance of population properties. Although some small but statistically significant inhomogeneities are found, the statistical description of depths in arbitrary intervals, such as annual total depths, is shown to be treatable as the sum of a random number of (independent) random variables by using the model for rainy day occurrence. Simulations from this model match well the measured data from the stations treated. The effect of truncation of the rainfall sample on both depth distribution and Markov chain dependence is discussed. It is also indicated how daily depths are functions, in turn, of individual storm occurrence probability (number per day) and storm depth distributions. In a previous paper [Smith andSchreiber, 1973], three sample stations with long (55-73 years) records from the Sonoran-Chihuahuan intermountain basins of southern Arizona-New Mexico were used to evaluate the validity of simple stochastic models for rainy day occurrences in this semiarid region for the summer thunderstorm season. A Markov chain model reproduced the observed occurrence patterns much better than an independent sequence model. This paper presents studies of the daily rainfall depths from the same stations, including a study of possible dependence connecting rainfall occurrence patterns and daily depths, and the combination of the two models (occurrence and depth) to provide information on the probability of the depth of rain in arbitrary periods. The utility of this information in hydrologic and watershed (range forage) studies is indicated. TOTAL SAMPLE DISTRIBUTION OF DAILY RAINFALL DEPTH The three sampling points providing data for this study are located in southeastern Arizona and were illustrated by Smith and Schreiber [1973, Figure 1]. Information about summer point rainfall in this region is expected to provide valuable assistance for studies of areal storm patterns on the heavily instrumented Walnut Gulch watershed at Tombstone. At the same time, this study is' intended to represent a large area of the Southwest. Although for some purposes it would be preferable to study the depth of rain within a time period small enough to distinguish separable storms occurring in 1 day, in a thunderstorm-dominated season the day is a natural time cycle for meteorological energy related to thunderstorm phenomena. If all rainfall day data are lumped and the total sample depth distribution is determined, the general shape of an arithmetic plotting indicates approximately an exponential distribution, given by P(l' _< x) = 1 -e -...
A new family of subsonic compressor airfoils, which are characterized by low losses and wide operating ranges, has been designed for use in heavy-duty gas turbines. In particular the influence of the higher airfoil Reynolds numbers compared to aeroengine compressors and the impact of these differences on the location of transition are taken into account. The design process itself is carried out by the combination of a geometrical code for the airfoil description, with a blade-to-blade solver and a numerical optimization algorithm. The optimization process includes the design-point losses for a specified Q3D flow problem and the off-design performance for the entire operating range. The family covers a wide range of inlet flow angle, Mach number, flow turning, blade thickness, solidity and AVDR in order to consider the entire range of flow conditions which occur in practical compressor design. The superior performance of the new airfoil family is demonstrated by a comparison with conventional controlled diffusion airfoils (CDA). The advantage in performance has been confirmed by detailed experimental investigations, which will be presented in Part II of the paper. This leads to the conclusion that CDA airfoils which have been primarily developed for aero engine applications are not the optimum solution, if directly transferred to heavy-duty gas turbines. A significant improvement in compressor efficiency is possible, if the new profiles are used instead of conventional airfoils.
Histoplasma capsulatum was recovered from the liver and spleen tissues of a species of predominantly insectivorous bats as well as from soil collected in a man-made harborage at Madden Air Field in the Republic of Panama.Although the recovery of the fungus Histoplasma capsulatum from soils enriched with bat or bird guano has been documented (1), successful attempts to recover it from the tissues of bats have not been reported. More than 100 bats were collected from a building adjacent to the air strip of the now-abandoned Madden Air Field, Republic of Panama. Within the building, the roosting habits of the bats were such that the guano collected could be related to the predominant bat using that particular roost. Three species of bats were recovered, Chilonycterus rubiginosa fusca, Carollia perspiculata azteca, and Phyllostomus hastatus panamensis. The latter species, an omnivore, was not examined for the presence of Histoplasma capsulatum. In addition to the bats and guano collected within the building, soil samples were taken at the entrance, under the eaves, and at the rear of the building. Thirty Chilonycterus rubiginosa fusca were killed in groups of five; livers and spleens were pooled and made into a homogeneous suspension with the aid of sterile sand, mortar, and pestle. The supernatant from this suspension was then inoculated onto two bloodfortified mycosel (2) plates and into each of five mice (0.2 ml intraperitoneally). Forty-five Carollia perspiculata azteca were processed in similar fashion, after a holding period of 22 days at the Corozal Veterinary Quarantine Station. Thus a total of six pools of Chilonycterus and nine pools of Carollia liver-and-spleen suspensions were sampled for the presence of Histoplasma capsulatum. None of the plates inoculated directly with the suspensions of liver and spleen revealed the presence of H. capsulatum. In addition, none of the mice inoculated with the tissues of Carollia perspiculata azteca yielded Histoplasma capsulatum when killed at varying times after inoculation. In contrast, two of the Chilonycterus pools (A445 and A447) yielded positive cultures. The Abstract. Histoplasma capsulatum was
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