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Preliminary investigation of a translating cowl technique for improving take-off performance of a sharp-lip supersonic diffuser

Description: A preliminary investigation was conducted in quiescent air on a translating cowl technique for improving the take-off performance of a sharp-lip supersonic diffuser. The technique consists of cutting the cowling in a plane normal to its axis and then translating the forepart of the cowling in the forward direction. The leading edge of the fixed portion of the cowling is rounded. Appreciable improved inlet performance was obtained with a cowling translation corresponding to a gap of only 1/4 inlet radius.
Date: November 28, 1951
Creator: Cortright, Edgar M , Jr
Partner: UNT Libraries Government Documents Department

A preliminary investigation of boundary-layer transition along a flat plate with adverse pressure gradient

Description: Boundary-layer surveys were made throughout the transition region along a smooth flat plate placed in an airstream of practically zero turbulence and with an adverse pressure gradient. The boundary-layer Reynolds number at the laminar separation point was varied from 1,800 to 2,600. The test data, when considered in the light of certain theoretical deductions, indicated that transition probably began with separation of the laminar boundary layer. The extent of the transition region, defined as the distance from a calculated laminar separation point to the position of the first fully developed turbulent boundary-layer profile, could be expressed as a constant Reynolds number run of approximately 70,000. Some speculations are presented concerning the application of the foregoing concepts, after certain assumptions have been made, to the problem of the connection between transition on the upper surface of an airfoil at high angles of attack and the maximum lift.
Date: March 1, 1938
Creator: Von Doenhoff, Albert E
Partner: UNT Libraries Government Documents Department

Preliminary Investigation of Certain Laminar-Flow Airfoils for Application at High Speeds and Reynolds Numbers

Description: In order to extend the useful range of Reynolds numbers of airfoils designed to take advantage of the extensive laminar boundary layers possible in an air stream of low turbulence, tests were made of the NACA 2412-34 and 1412-34 sections in the NACA low-turbulence tunnel. Although the possible extent of the laminar boundary layer on these airfoils is not so great as for specially designed laminar-flow airfoils, it is greater than that for conventional airfoils, and is sufficiently extensive so that at Reynolds numbers above 11,000,000 the laminar region is expected to be limited by the permissible 'Reynolds number run' and not by laminar separation as is the case with conventional airfoils. Drag measurements by the wake-survey method and pressure-distribution measurements were made at several lift coefficients through a range of Reynolds numbers up to 11,400,000. The drag scale-effect curve for the NACA 1412-34 is extrapolated to a Reynolds number of 30,000,000 on the basis of theoretical calculations of the skin friction. Comparable skin-friction calculations were made for the NACA 23012. The results indicate that, for certain applications at moderate values of the Reynolds number, the NACA 1412-34 and 2412-34 airfoils offer some advantages over such conventional airfoils as the NACA 23012. The possibility of maintaining a more extensive laminar boundary layer on these airfoils should result in a small drag reduction, and the absence of pressure peaks allows higher speeds to be reached before the compressibility burble is encountered. At lower Reynold numbers, below about 10,000,000, these airfoils have higher drags than airfoils designed to operate with very extensive laminar boundary layers.
Date: August 1, 1939
Creator: Jacobs, E.N.; Abbott, Ira H. & von Doenhoff, A.E.
Partner: UNT Libraries Government Documents Department

Preliminary investigation of combustion of diborane in a turbojet combustor

Description: Boron and its hydrides offer increased flight range relative to conventional fuels for turbojet engines. Preliminary evaluation has been made of the combustion characteristics and deposition problems resulting from burning diborone in a single, modified J33 combustor. A combustor relatively free of deposits for the limited test conditions has been developed. Three possible methods of alleviating deposits on the turbine blades are reported.
Date: February 13, 1957
Creator: Kaufman, Warner B; Gibbs, James B & Branstetter, J Robert
Partner: UNT Libraries Government Documents Department

Preliminary investigation of cooling-air ejector performance at pressure ratios from 1 to 10

Description: Preliminary investigation was made of conical cooling air ejector at primary pressure ratios from 1 to 10. The cooling-air flow was maintained at zero and the resulting pressure variation in the shroud indicated pumping ability. The cooling-air flow was maintained at zero and the resulting pressure variation in the shroud indicated pumping ability. The gross thrust of the ejector and nozzle were compared. Several ratios of the spacing between the nozzle and shroud exit to the nozzle exit diameter were investigated for several shroud to nozzle exit diameter ratios. Maximum gross thrust loss occurred under conditions of zero cooling-air flow and was as much as 35 percent below nozzle jet thrust. For minimum thrust loss, ejector should be designed with as low diameter and spacing ratio as possible.
Date: October 17, 1951
Creator: Ellis, C W; Hollister, D P & Sargent, A F , Jr
Partner: UNT Libraries Government Documents Department

Preliminary investigation of corrosion by molten sodium hydroxide flowing in tubes of AISI 347 stainless steel, Inconel, and nickel having average outer-wall temperatures of 1500 F and a circumferential temperature gradient of 20 F

Description: Experiments were performed with an apparatus suitable for determining corrosive effects of hot flowing liquids on various container materials. The investigation was conducted with molten sodium hydroxide flowing at a velocity of 15 feet per second. Extensive corrosion and mass trans Extensive corrosion and mass transfer to regions of reduced temperature was observed.
Date: March 1, 1952
Creator: Mosher, Don R & Desmon, Leland G
Partner: UNT Libraries Government Documents Department

Preliminary Investigation of Cyclic De-Icing of an Airfoil Using an External Electric Heater

Description: An investigation was conducted in the NACA Lewis icing research tunnel to determine the characteristics and requirements of cyclic deicing of a 65,2-216 airfoil by use of an external electric heater. The present investigation was limited to an airspeed of 175 miles per hour. Data are presented to show the effects of variations in heat-on and heat-off periods, ambient air temperature, liquid-water content, angle of attack, and. heating distribution on the requirements for cyclic deicing. The external heat flow at various icing and heating conditions is also presented. A continuously heated parting strip at the airfoil leading edge was found necessary for quick, complete, and consistent ice removal. The cyclic power requirements were found to be primarily a function of the datum temperature and heat-on time, with the other operating and meteorological variables having a second-order effect. Short heat-on periods and high power densities resulted in the most efficient ice removal, the minimum energy input, and the minimum runback ice formations. The optimum chordwise heating distribution pattern was found to consist of a uniform distribution of cycled power density in the impingement region. Downstream of the impingement region the power density decreased to the limits of heating which, for the conditions investigated, extended from 5.7 percent chord on the upper surface of the airfoil to 8.9 percent chord on the lower surface. Ice removal did not take place at a heater surface temperature of 32 F; surface temperatures of approximately 50 to 100 F were required to effect removal. Better de-icing performance and greater energy savings would be possible with a heater having a higher thermal efficiency.
Date: February 4, 1952
Creator: Lewis, James P. & Bowden, Dean T.
Partner: UNT Libraries Government Documents Department

Preliminary investigation of effect on performance of dividing conical-spike nose inlets into halves at Mach numbers 1.5 to 2.0

Description: Inserting a splitter plate in the subsonic diffuser caused a pressure-recovery loss of about 1 percent for an inlet with a long nearly constant-area throat section. The loss was due to the increased surface area. Another inlet, which had a comparatively rapid area increase immediately after the throat, experienced pressure-recovery losses of 5 and 6 percent at Mach numbers of 1.8 and 2.0, respectively, and about 1 percent at Mach 1.5.
Date: December 19, 1955
Creator: Allen, John L
Partner: UNT Libraries Government Documents Department