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Prediction of Tube Bundle Instabilities : Case Studies

Description: The concurrent acquisition of flow-induced vibration (FIV) test data for several configurations of an industrial-size shell-and-tube heat exchanger made possible this evaluation of the HXVA method for six cases. Recommendations to improve the prediction capability were made, with priority on the excitation mechanism for dense fluid flows with non-uniform velocity distributions.
Date: November 1986
Creator: Mulcahy, T. M.; Halle, Henry & Wambsganss, M. W.
Partner: UNT Libraries Government Documents Department

Preignition characteristics of several fuels under simulated engine conditions

Description: The preignition characteristics of a number of fuels have been studied under conditions similar to those encountered in an engine. These conditions were simulated by suddenly compressing a fuel-air mixture in contact with an electrically heated hot spot in the cylinder head of the NACA combustion apparatus. Schlieren photographs and indicator cards were taken of the burning, and the hot-spot temperatures necessary to cause ignition under various conditions were determined.
Date: January 1, 1941
Creator: Spencer, R C
Partner: UNT Libraries Government Documents Department

A preignition indicator for aircraft engines

Description: Report describes an electrical-relay circuit that uses cylinder thermocouples for indicating preignition or misfiring in an aircraft engine. The potential dangers of preignition and the importance of an easy-to-use, practical preignition indicator are provided. The operating principles of the indicator and a description of its functioning, calibration, and installation procedures are also included.
Date: February 1945
Creator: Dallas, Thomas & Harries, Myron L..
Partner: UNT Libraries Government Documents Department

Preignition-limited performance of several fuels

Description: Preignition-limited performance data were obtained on a supercharged CFR engine at two sets of operating conditions over a wide range of fuel-air ratios to determine the preignition characteristics for the following five fuels: s-3 reference fuel, s-3 plus 4 ml. tel per gallon, afd-33(140-p), benzene, and diisobutylene. Maximum thermal-plug temperatures at constant intake-air pressures were also determined to correlate the preignition characteristics of each fuel with its ability to increase general engine-temperature levels. Additional runs were made to compare the preignition-limited performance of triptane, triptane plus 4 ml. tel per gallon, and an-f-28r fuel.
Date: January 1, 1945
Creator: Male, Donald W & Evvard, John C
Partner: UNT Libraries Government Documents Department

Preimpoundment Water Quality in the Tioga River Basin, Pennsylvania and New York

Description: Introduction: The U.S. Geological Survey, in cooperation with the U.S. Army Corps of Engineers, and aided by the Susquehanna River Basin Commission, investigated the water quality of the Tioga River basin, Pennsylvania. The study, made from September 1973 to September 1978, was designed to evaluate water quality at various sites prior to impoundment. Results of the investigation will aid the Corps of Engineers in designing the operation of three reservoirs that were in the final stages of construction in late 1979.
Date: March 1981
Creator: Ward, Janice R.
Partner: UNT Libraries Government Documents Department

Preimpoundment Water Quality of Raystown Branch Juniata River and Six Tributary Streams, South-Central Pennsylvania

Description: Abstract: The Raystown Branch Juniata River watershed, which is the main water source for Raystown Lake, is a 960-square-mile (2,490 square kilometers) drainage basin in south-central Pennsylvania. Preimpoundment water-quality data were collected on the Raystown Branch and six tributary streams in the basin. Specific conductance values varied inversely with water discharge. The pH values were extremely low only at the Shoup Run site. Dissolved oxygen concentrations observed at all sites indicated a relatively high oxygen saturation level throughout the year. Seasonal variations in nitrate-N and orthophosphate-P levels were measured at the main inflow station at Saxton, Pa. The highest concentrations of nitrate-N and orthophosphate-P occurred in the winter and spring months and the lowest concentrations were measured during the summer and fall. Bacteriological data indicated no excessive amounts of fecal matter present at the in-flows. Soil samples collected at four sites in the impoundment area were predominantly of the Barbour, Philo, and Basher series, which are considered to be highly fertile soils with silt-loam and sandy-loam textures. Morphological features of the lake basin and lo~ nutrient levels at the ·inflows should prevent excessive weed growth around the lake perimeter.
Date: June 1976
Creator: Williams, Donald R.
Partner: UNT Libraries Government Documents Department

Preimpoundment Water Quality of the Wild Rice River, Norman County, Minnesota

Description: From abstract: This report uses water samples collected from two sites at the Wild Rice River in Minnesota to "establish baseline water-quality characteristics before construction of a reservoir near Twin Valley, Minnesota for recreation and flood control." It contains a map, graphs, and tables.
Date: June 1980
Creator: Tornes, Lan H.
Partner: UNT Libraries Government Documents Department

Preknock vibrations in a spark-ignition engine cylinder as revealed by high-speed photography

Description: The high-speed photographic investigation of the mechanics of spark-ignition engine knock recorded in three previous reports has been extended with use of the NACA high-speed camera and combustion apparatus with a piezoelectric pressure pickup in the combustion chamber. The motion pictures of knocking combustion were taken at the rate of 40,000 frames per second. Existence of the preknock vibrations in the engine cylinder suggested in Technical Report no.727 has been definitely proved and the vibrations have been analyzed both in the high-speed motion pictures and the pressure traces. Data are also included to show that the preknock vibrations do not progressively build up to cause knock. The effect of tetraethyl lead on the preknock vibrations has been studied and results of the tests are presented. Photographs are presented which in some cases clearly show evidence of autoignition in the end zone a considerable length of time before knock occurs.
Date: January 1, 1944
Creator: Miller, Cearcy D & Logan, Walter O , Jr
Partner: UNT Libraries Government Documents Department

Preliminary Aerodynamic Data Pertinent to Manned Satellite Reentry Configurations

Description: Report presenting some experimental data and calculations for a variety of aerodynamic shapes considered for use as manned reentry vehicles. Three types of vehicles were tested: non-lifting bodies, lifting bodies, and airplane-like vehicles. All of the configuration types were found to be suitable for use as manned reentry vehicles with certain fin and flap modifications for certain shapes.
Date: July 21, 1958
Creator: Penland, Jim A. & Armstrong, William O.
Partner: UNT Libraries Government Documents Department

Preliminary Air-Flow and Thrust Calibrations of Several Conical Cooling-Air Ejectors with a Primary to Secondary Temperature Ratio of 1.0, 2, Diameter Ratios of 1.06 and 1.40

Description: An investigation was made of the performance of nine conical cooling-air ejectors at primary jet pressure ratios from 1 to 10, secondary pressure ratios to 4.0, and a temperature ratio of unity. This phase of the investigation was limited to conical ejectors having shroud exit to primary nozzle exit diameter ratios of 1.06 and 1.40, with several spacing ratios for each. The experimental results indicated that the pumping range and amount of cooling-air flow obtained with a 1.06 diameter ratio ejector were relatively small for cooling purposes but that the maximum possible thrust loss, which occurred with no secondary flow, was only 7 percent of convergent nozzle thrust. The 1.40 diameter ratio ejector produced a large cooling air flow and showed a possible thrust loss of 29.5 percent with no cooling air flow. Thrust gains were attained with ejectors of both diameter ratios at secondary pressure ratios greater than 1.0. The limiting primary pressure ratio below which an ejector can operate at a specific secondary pressure ratio (cut-off point) may be estimated for various flight conditions from data contained herein.
Date: August 12, 1952
Creator: Greathouse, W. K. & Hollister, D. P.
Partner: UNT Libraries Government Documents Department

Preliminary Altitude Operational Characteristics of a J57-P1 Turbojet Engine

Description: The operational characteristics of a J57-P1 turbojet engine have been investigated at altitudes between 15,000 and 66,000 feet in the Lewis altitude wind tunnel. Included in this study is a discussion of fuel nozzle coking, the altitude operating limits with and without the standard engine control, the compressor surge characteristics, and the engine starting and windmilling characteristics. Severe circumferential turbine outlet temperature gradients which occurred at high altitude as a result of fuel nozzle coking were alleviated by the manufacturer's change in the fuel flow divider schedule and in a nozzle gasket material. Compressor air bleed is required to prevent surge of the outboard compressor in the low engine speed region. The maximum altitude at which the engine was operated without the control was about 66,000 feet at 0.8 flight Mach number and at a reduced engine speed to avoid compressor surge; with the engine control in operation, the altitude operating limit is reduced to approximately 59,000 feet. The maximum altitude at which the engine was started was about 40,000 feet.
Date: March 31, 1954
Creator: Wallner, Lewis E. & Saari, Martin J.
Partner: UNT Libraries Government Documents Department

Preliminary Altitude Performance Characteristics of the J57-P-1 Turbojet Engine with Fixed-area Exhaust Nozzle

Description: An investigation to determine the altitude performance of the J57-P-1 turbojet engine and components was conducted at the NACA Lewis altitude wind tunnel. Data were obtained over a corrected inboard rotor speed range from 56 to 106 percent of rated speed, with intercompressor bleeds both open and closed, at altitudes from 15,000 to 50,000 feet and at a flight Mach number of 0.81. The corresponding range of Reynolds number indices was from 0.858 to 0.213. All data presented were obtained with a fixed-area exhaust nozzle sized according to the manufacturer's specification. Over-all engine performance parameters are presented as functions of inboard rotor speed corrected on the basis of engine inlet temperature. Component parameters are presented as functions of their respective corrected rotor speeds. A tabulation of all performance data is included in addition to the graphical presentation. Corrected net thrust is unusually sensitive to changes in corrected inboard rotor speed in the high speed region. A change of 1 percent in speed, at sated speed, produced a change of 6 percent in corrected net thrust . At rated engine speed, increasing the altitude from 15,000 to 50,000 feet at a constant flight Mach number of 0.81 increased the specific fuel consumption 13 percent but did not affect corrected net thrust.
Date: April 30, 1954
Creator: Bloomer, Harry E. & Miller, Robert R.
Partner: UNT Libraries Government Documents Department

Preliminary Altitude Performance Data for the J65-B3 Turbojet Engine at Reynolds Number Indices from 0.2 to 0.8

Description: Altitude performance characteristics of the J65-B3 turbojet engine and its components were obtained at engine-inlet conditions corresponding to Reynolds number indices from 0.2 to 0.8 over a range of corrected engine speeds from 70 to 110 percent of rated speed. Engine operational limits up to an altitude of 75,000 feet together with ignition and windmilling characteristics were also obtained. The engine and component data are presented both in graphical and in tabulated form. The operational characteristics are presented in graphical form.
Date: August 23, 1954
Creator: Braithwaite, W.M. & Greathouse, W.K.
Partner: UNT Libraries Government Documents Department

Preliminary Altitude Performance Data for the J71-A2 (X-26) Turbojet Engine

Description: Data were obtained in an altitude test chamber for a range of altitudes from 20,000 to 58,000 feet at a flight Mach number of 0.9, and for several flight Mach numbers at an altitude of 45,000 feet. Data approximating sea-level operation are also included. Engine component performance data are presented in addition to windmilling, exhaust-nozzle, and ejector performance.
Date: August 19, 1954
Creator: Useller, James W. & Mallett, William E.
Partner: UNT Libraries Government Documents Department

Preliminary Altitude Performance Data of J71-A2 Turbojet Engine Afterburner

Description: The performance and operational characteristics of the J71-A2 turbojet-engine afterburner were investigated for a range of altitudes from 23,000 to 60,000 feet at a flight Mach number of 0,9 and at flight Mach numbers of 0.6, 0.9, and 1.0 at an altitude of 45,000 feet. The combustion performance and altitude operational limits, as well as the altitude starting characteristics have been determined.
Date: October 7, 1954
Creator: Useller, James W. & Mallett, William E.
Partner: UNT Libraries Government Documents Department

Preliminary analysis of a nuclear powered supersonic airplane using ramjet engines

Description: Report discussing performance estimates for several airplanes using General Electric AC-210 ramjet nuclear-powered engines. Assumptions used for designing the engines, radiation shield, and airframe are described. Potential tradeoffs in regards to power and weight reduction are also discussed.
Date: April 11, 1958
Creator: Weber, Richard J. & Connolley, Donald J.
Partner: UNT Libraries Government Documents Department

Preliminary Analysis of Axial-Flow Compressors Having Supersonic Velocity at the Entrance of the Stator

Description: A supersonic compressor design having supersonic velocity at the entrance of the stator is analyzed on the assumption of two-dimensional flow. The rotor and stator losses assumed in the analysis are based on the results of preliminary supersonic cascade tests. The results of the analysis show that compression ratios per stage of 6 to 10 can be obtained with adiabatic efficiency between 70 and 80 percent. Consideration is also given in the analysis to the starting, stability, and range of efficient performance of this type of compressor. The desirability of employing variable-geometry stators and adjustable inlet guide vanes is indicated. Although either supersonic or subsonic axial component of velocity at the stator entrance can be used, the cascade test results suggest that higher pressure recovery can be obtained if the axial component is supersonic.
Date: September 12, 1949
Creator: Ferri, Antonio
Partner: UNT Libraries Government Documents Department