Pitot-Pressure Measurements in Flow Fields Behind a Rectangular Nozzle with Exhaust Jet for Free-Stream Mach Numbers of 0.00, 0.60, and 1.20

An investigation has been conducted in the Langley 16-Foot Transonic Tunnel to measure the flow field in and around the jet exhaust from a nonaxisymmetric nozzle configuration. The nozzle had a rectangular exit with a width-to-height ratio of 2.38. Pitot-pressure measurements were made at five longitudinal locations downstream of the nozzle exit. The maximum distance downstream of the exit was about 5 nozzle heights. These measurements were made at free-stream Mach numbers of 0.00, 0.60, and 1.20 with the nozzle operating at a ratio of nozzle total pressure to free-stream static pressure of 4.0. The jet exhaust was simulated with high-pressure air that had an exit total temperature essentially equal to the free-stream total temperature

Validation and Simulation of ARES I Scale Model Acoustic Test -1- Pathfinder Development

The Ares I Scale Model Acoustics Test (ASMAT) is a series of live-fire tests of scaled rocket motors meant to simulate the conditions of the Ares I launch configuration. These tests have provided a well documented set of high fidelity measurements useful for validation including data taken over a range of test conditions and containing phenomena like Ignition Over-Pressure and water suppression of acoustics. To take advantage of this data, a digital representation of the ASMAT test setup has been constructed and test firings of the motor have been simulated using the Loci/CHEM computational fluid dynamics software. Within this first of a series of papers, results from ASMAT simulations with the rocket in a held down configuration and without water suppression have then been compared to acoustic data collected from similar live-fire tests to assess the accuracy of the simulations. Detailed evaluations of the mesh features, mesh length scales relative to acoustic signals, Courant-Friedrichs-Lewy numbers, and spatial residual sources have been performed to support this assessment. Results of acoustic comparisons have shown good correlation with the amplitude and temporal shape of pressure features and reasonable spectral accuracy up to approximately 1000 Hz. Major plume and acoustic features have been well captured including the plume shock structure, the igniter pulse transient, and the ignition overpressure. Finally, acoustic propagation patterns illustrated a previously unconsidered issue of tower placement inline with the high intensity overpressure propagation path

SEQUENTIAL STOCHASTIC PRODUCTION DECISIONS FOR A PERENNIAL CROP: THE YIELD/QUALITY TRADEOFF FOR ALFALFA HAY

The "optimal cutting schedule" for alfalfa hay is described as a function of the trade-off between rising yield and falling quality of alfalfa over time and the local market prices being offered for different qualities of hay during the harvest season. Field test results quantify the yield/quality tradeoff for a California case study. A general decision rule is then derived to assist growers in making cutting decisions during a season. Finally, the optimal cutting schedule is shown to be the sum of sequential decisions for cuttings throughout the harvest season, with no schedule being best a priori.Crop Production/Industries,

The Mono Craters, California

The Mono Craters are a unique series of obsidian domes and coulees south of Mono Lake, in eastern California. From an undulating, pumice-covered plain their steep slopes rise nearly 2700 feet above the surrounding country and reach an altitude of 9169 feet at the summit of the highest dome. Were the range not dwarfed by the neighboring Sierra Nevada, "it would be far-famed for its magnificent scenery as well as for its geological interest." The Mono Craters present many features of interest. Their relationship to the lacustrine record of Mono Lake and the glacial history of the eastern Sierra Nevada is important. Added interest to the problem is afforded by the water tunnel under construction by the city of Los Angeles, which passes beneath one of the larger domes at the south end of the chain. This tunnel is to convey water from the Mono Basin into the drainage of the Owens River and, by the present aqueduct, to Los Angeles. The work has been impeded by the large quantity of water encountered in the tunnel and the presence of carbon dioxide (see Fig. 16). On the other hand, there is the fortunate circumstance that the tunnel line passes through an area suitable for the determination of the age of the craters. All the important rocks of the region crop out, and in this area the glacial and volcanic records overlap