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Impingement of droplets in 90 degree elbows with potential flow

Description: Trajectories were determined for droplets in air flowing through 90 deg elbows especially designed for two-dimensional potential motion with low pressure losses. The elbows were established by selecting as walls of each elbow two streamlines of the flow field produced by a complex potential function that establishes a two-dimensional flow around a 90 deg bend. An unlimited number of elbows with slightly different shapes can be established by selecting different pairs of streamlines as walls. The elbows produced by the complex potential function selected are suitable for use in aircraft air-intake ducts.
Date: September 1953
Creator: Hacker, Paul T.; Brun, Rinaldo J. & Boyd, Bemrose
Partner: UNT Libraries Government Documents Department

Full-Scale Wind-Tunnel Investigation of Forward Underslung Cooling-Air Ducts

Description: Report presenting an investigation of underslung cooling-air ducts in various locations on a model of a typical single-engine tractor airplane in the full-scale tunnel. The report contains the results of tests of two forward underslung ducts. Results regarding pressure recoveries at the radiator, pressures behind the radiator, drag and duct efficiency, and critical speeds are provided.
Date: October 1944
Creator: Nelson, W. J.; Czarnecki, K. R. & Harrington, Robert D.
Partner: UNT Libraries Government Documents Department

Wind-tunnel investigation of rear underslung fuselage ducts

Description: Report discussing an investigation of cooling ducts at various positions on a model of a typical pursuit airplane in the NACA full-scale tunnel. Results in the report are given for a duct located on the bottom of the fuselage with the inlet behind the leading edge of the wing. Due to the thick boundary layers at the inlets of the rear underslung fuselage duct and the serious pressure losses that resulted, a special vane was also installed to avoid boundary-layer separation.
Date: September 1943
Creator: Czarnecki, K. R. & Nelson, W. J.
Partner: UNT Libraries Government Documents Department

Effect of unequal air-flow distribution from twin inlet ducts on performance of an axial-flow turbojet engine

Description: Report presenting an investigation in the NACA altitude test chamber to determine the effect of inlet-air-flow distortion on the performance of an axial-flow turbojet engine with simulated twin inlet ducts. Results regarding the pressure and temperature profiles, component performance, overall engine performance, and operational comments are provided.
Date: August 3, 1954
Creator: Walker, Curtis L.; Sivo, Joseph N. & Jansen, Emmert T.
Partner: UNT Libraries Government Documents Department

Elimination of rumble from the cooling ducts of a single-engine pursuit airplane

Description: Report presenting a full-size single-engine pursuit airplane, with wing tips cut off, tested in the 16-foot wind tunnel. The purpose was to find means for eliminating an extreme rumble which occurred at high speeds when the radiator air-duct-exit openings were small. Results regarding rumble, cooling air, and drag are provided.
Date: August 1943
Creator: Matthews, Howard F.
Partner: UNT Libraries Government Documents Department

Wind-tunnel investigation at low speed of effect of size and position of closed air ducts on static longitudinal and static lateral stability characteristics of unswept-midwing models having wings of aspect ratio 2, 4, and 6

Description: Report presenting an investigation at Mach number 0.13 in the stability tunnel to determine the effects of closed wing-root air ducts on the static longitudinal and lateral stability characteristics of unswept-midwing models with wings of aspect ratio 2, 4, and 6.
Date: September 1955
Creator: Jaquet, Byron M. & Williams, James L.
Partner: UNT Libraries Government Documents Department

Method for rapid determination of pressure change for one-dimensional flow with heat transfer, friction, rotation, and area change

Description: Report presenting the development of an approximate method for rapid determination of the pressure change for subsonic flow of a compressible fluid under the simultaneous action of heat transfer, friction, rotation, and area change. The report presents the analysis involved in simplifying the momentum equation and the charts necessary for obtaining particular solutions.
Date: June 1954
Creator: Hubbartt, James E.; Slone, Henry O. & Arne, Vernon L.
Partner: UNT Libraries Government Documents Department

Preliminary Investigation of the Supersonic Flow Field Downstream of Wire-Mesh Nozzles in a Constant-Area Duct

Description: "An investigation was conducted in a 3.4- by 3.4-inch duct to determine the characteristics of the supersonic flow downstream of four wire-mesh screen nozzles with nominal design Mach numbers in the range between 1.97 and 2.58. Two types of disturbances were observed in the flow field: a fine network of interacting expansion and compression waves which were formed immediately downstream of the screens and appeared to dissipate within 25 to 40 wave intersections; and relatively strong oblique shock waves that originated at the junctions of the screens and the walls and were reflected throughout the length of the duct. Regions of fairly uniform flow were found to exist" (p. 1).
Date: August 14, 1951
Creator: Gould, Lawrence I.
Partner: UNT Libraries Government Documents Department

Preliminary Study of Stability of Flow From Two Ducts Discharging Into a Common Duct

Description: Note presenting an investigation of the instability of flow from two ducts that join into a common duct and of the influence of the various parameters on the phenomenon. A two-dimensional potential analysis was carried out under the assumption that the two ducts discharge into a region of constant pressure.
Date: July 1951
Creator: Bellin, Albert I.; Messina, D. Richard & Richards, Paul B.
Partner: UNT Libraries Government Documents Department

Full-Scale Wind-Tunnel Investigation of Wing-Cooling Ducts Effects of Propeller Slipstream, Special Report

Description: The safety of remotely operated vehicles depends on the correctness of the distributed protocol that facilitates the communication between the vehicle and the operator. A failure in this communication can result in catastrophic loss of the vehicle. To complicate matters, the communication system may be required to satisfy several, possibly conflicting, requirements. The design of protocols is typically an informal process based on successive iterations of a prototype implementation. Yet distributed protocols are notoriously difficult to get correct using such informal techniques. We present a formal specification of the design of a distributed protocol intended for use in a remotely operated vehicle, which is built from the composition of several simpler protocols. We demonstrate proof strategies that allow us to prove properties of each component protocol individually while ensuring that the property is preserved in the composition forming the entire system. Given that designs are likely to evolve as additional requirements emerge, we show how we have automated most of the repetitive proof steps to enable verification of rapidly changing designs.
Date: March 1939
Creator: Nickle, F. R. & Freeman, Arthur B.
Partner: UNT Libraries Government Documents Department

An Experimental Investigation of NACA Submerged-Duct Entrances

Description: The results of an investigation of submerged-duct entrances are presented. It is shown that this type of entrance possesses the following characteristics: 1) very high-critical-compressibility speeds throughout the range of high-speed inlet velocity ratios; 2) very low pressure losses for the air entering the duct at all inlet-velocity ratios; and, 3) low external drag. These characteristics are obtained by the proper shaping of the contour of the upstream approach to the submerged inlets and by proper alignment of the duct lip. Design data are presented and the application of these data to a specific high-speed fighter-airplane design is discussed.
Date: May 23, 1945
Creator: Frick, Charles W.; Davis, Wallace F.; Randall, Lauros & Mossman, Emmet A.
Partner: UNT Libraries Government Documents Department

Experimental investigation at supersonic speeds of twin-scoop duct inlets of equal area I : an inlet enclosing 61.5 percent of the maximum circumference of the forebody

Description: Report presenting tests at Mach numbers between 1.36 and 2.01 of a twin-scoop air intake enclosing 61.5 percent of the maximum circumference of a body of revolution and located five forebody diameters behind the apex, which showed that the total pressure recovered after diffusion was about 10 percent greater than that attained in previous tests with an annular entrance of the same area.
Date: January 21, 1948
Creator: Davis, Wallace F. & Goldstein, David L.
Partner: UNT Libraries Government Documents Department

The Design of Cooling Ducts With Special Reference to the Boundary Layer at the Inlet

Description: "A study has been made of underslung cooling ducts with special references to the problems presented by the boundary layer on the fuselage skin. It was found that good flow can be obtained in such ducts by (1) making the inlet opening of such size that the mean inlet velocity is about 0.6 the free-stream velocity and (2) providing vanes behind as well as ahead of the radiator. Tables to facilitate design are included, together with an example " (p. 1).
Date: December 1940
Creator: Katzoff, S.
Partner: UNT Libraries Government Documents Department

Wind-Tunnel Investigation of Wing Ducts on a Single Engine Pursuit Airplane

Description: Report presenting a study of several ducts installed in the wings of a model of a conventional single-engine pursuit airplane in the full-scale tunnel to determine the influence of inlet design and cooling-air flow on the pressure losses within the duct and on the aerodynamic characteristics of the airplane. Large differences in the total pressure at the radiator occurred as a result of variations in the inlet-velocity ratio, the lift coefficient, the shape and position of the inlet, the slope of the diffuser axis, and propeller operation.
Date: October 1943
Creator: Nelson, W. J. & Czarnecki, K. R.
Partner: UNT Libraries Government Documents Department

Investigation of air flow in right-angle elbows in a rectangular duct

Description: Report presenting testing on elbow shapes in airplane carburetor air intake ducts with low losses and good velocity distribution without the use of turning vanes. Results regarding the flow coefficient, velocity distribution, and comparison of a variety of elbow ducts are provided.
Date: October 1941
Creator: McLellan, Charles H. & Bartlett, Walter A., Jr.
Partner: UNT Libraries Government Documents Department

Experiments on the Recovery of Waste Heat in Cooling Ducts, Special Report

Description: Tests have been conducted in the N.A.C.A. full-scale wind tunnel to investigate the partial recovery of the heat energy which is apparently wasted in the cooling of aircraft engines. The results indicate that if the radiator is located in an expanded duct, a part of the energy lost in cooling is recovered; however, the energy recovery is not of practical importance up to airplane speeds of 400 miles per hour. Throttling of the duct flow occurs with heated radiators and must be considered in designing the duct outlets from data obtained with cold radiators in the ducts.
Date: May 1939
Creator: Silverstein, Abe
Partner: UNT Libraries Government Documents Department

The influence of vortex generators on the performance of a short 1.9:1 straight-wall annular diffuser with a whirling inlet flow

Description: Report presenting an investigation in a duct system with fully developed pipe flow to determine the effects of vortex generators on the performance of a diffuser with whirling inlet flow. Testing was made with three different inlet whirl angles and rectangular, noncambered airfoils that varied in chord, span, angle setting, number, and location. Results for the 20.6 degree inlet whirl angle, 15.2 degree inlet whirl angle, 0 degree inlet whirl angle, and effect of inlet whirl angle on diffuser performance are provided.
Date: February 9, 1953
Creator: Wood, Charles C. & Higginbotham, James T.
Partner: UNT Libraries Government Documents Department

Pressure Recovery at Supersonic Speeds Through Annular Duct Inlets Situated in a Region of Appreciable Boundary Layer 2: Effect of an Oblique Shock Wave Immediately Ahead of the Inlet

Description: Memorandum presenting an investigation of a model with a ramp that produced an oblique shock wave in front of an annular duct inlet, which was tested at Mach numbers between 1.36 and 2.01 to determine the effect of reducing the entrance Mach number on the total-pressure recovery after diffusion. The results showed that the maximum total-pressure recovery of the model investigated was considerably improved through the addition of a ramp.
Date: August 9, 1948
Creator: Brajnikoff, George B.
Partner: UNT Libraries Government Documents Department

Truss-Integrated Thermoformed Ductwork Final Technical Report

Description: This report summarizes a multi-year research effort to develop a leak-free duct system that can be readily installed within the thermal envelope. There are numerous efforts underway to improve duct system efficiency. Most of these involve modifications to current technology such as air sealing techniques like mastic and aeroseal, snap together duct connections, and greater levels of insulation. This project sought to make a more significant stride forward by introducing a duct system of a material that can be more readily sealed and can exhibit lower friction losses. The research focused on the use of smooth internal surface, low friction plastic ducts that could be easily installed with very low air leakage. The initial system concept that was proposed and researched in Phase I focused on the use of thermoformed plastic ducts installed in a recessed roof truss underneath the attic insulation. A bench top thermoformed system was developed and tested during Phase I of the project. In Phase II, a first generation duct system utilizing a resin impregnated fiberglass duct product was designed and specified. The system was installed and tested in an Atlanta area home. Following this installation research and correspondence with code officials was undertaken to alleviate the continued concern over the code acceptance of plastic ducts in above ground applications. A Committee Interpretation response was received from the International Code Council (ICC) stating that plastic ducts were allowed, but must be manufactured from materials complying with Class 0 or Class 1 rating. With assurance of code acceptance, a plastic duct system using rotomolded high density polyethylene ducts that had passed the material test requirements by impregnating the material with a fire retardant during the molding process was installed in the basement of a new ranch-style home in Madison, WI. A series of measurements to evaluate the ...
Date: August 30, 2007
Creator: Winter, Steven; Griffiths, Dianne & Gorthala, Ravi
Partner: UNT Libraries Government Documents Department


Description: A collimated portable gamma-ray detector will be used to quantify the plutonium content of items that can be approximated as a point, line, or area geometry with respect to the detector. These items can include ducts, piping, glove boxes, isolated equipment inside of gloveboxes, and HEPA filters. The Generalized Geometry Holdup (GGH) model is used for the reduction of counting data. This document specifies the calculations to reduce counting data into contained plutonium and the associated total measurement uncertainty.
Date: February 1, 2005
Creator: BD, KEELE
Partner: UNT Libraries Government Documents Department