Showing papers by "Langley Research Center published in 1971"
01 Jan 1971
TL;DR: Al alloy sheet fatigue crack closure under cyclic tensile loading, deriving expression for crack propagation rate in terms of effective stress amplitude as discussed by the authors, was derived for the first time in the literature.
Abstract: Al alloy sheet fatigue crack closure under cyclic tensile loading, deriving expression for crack propagation rate in terms of effective stress amplitude
1,809 citations
TL;DR: In this article, the leading edge suction analogy for predicting low speed lift and drag due-to-lift characteristics of sharp edge delta and related wing planforms was used to predict a low speed aircraft.
Abstract: Leading edge suction analogy for predicting low speed lift and drag-due-to-lift characteristics of sharp edge delta and related wing planforms
497 citations
01 Aug 1971
TL;DR: Boundary collocation for two dimensional stress analysis of cracks emanating from or from near holes with various shapes was proposed in this paper, which is based on the concept of boundary collocation.
Abstract: Boundary collocation for two dimensional stress analysis of cracks emanating from or from near holes with various shapes
326 citations
TL;DR: The present paper assumes that a functional relationship between potential level and mitotic activity does in fact exist and proceeds with the formulation of a basic theory of mitosis control wherein the intracellular ionic conditions associated with various levels of the potential difference act to regulate preparation for DNA synthesis and other essential mitotic preparations.
285 citations
01 Nov 1971
TL;DR: In this article, the stagnation-point convective heat transfer to an axisymmetric blunt body for arbitrary gases in chemical equilibrium was investigated and a general equation for the stagnation point convective heating transfer in base gases and gas mixtures was derived and is a function of the mass fraction, the molecular weight and a transport parameter of the base gases.
Abstract: The stagnation-point convective heat transfer to an axisymmetric blunt body for arbitrary gases in chemical equilibrium was investigated. The gases considered were base gases of nitrogen, oxygen, hydrogen, helium, neon, argon, carbon dioxide, ammonia, and methane and 22 gas mixtures composed of the base gases. Enthalpies ranged from 2.3 to 116.2 MJ/kg, pressures ranged from 0.001 to 100 atmospheres, and the wall temperatures were 300 and 1111 K. A general equation for the stagnation-point convective heat transfer in base gases and gas mixtures was derived and is a function of the mass fraction, the molecular weight, and a transport parameter of the base gases. The relation compares well with present boundary-layer computer results and with other analytical and experimental results. In addition, the analysis verified that the convective heat transfer in gas mixtures can be determined from a summation relation involving the heat transfer coefficients of the base gases. The basic technique developed for the prediction of stagnation-point convective heating to an axisymmetric blunt body could be applied to other heat transfer problems.
252 citations
01 Feb 1971
TL;DR: Computer program for estimating subsonic aerodynamic characteristics of various aerodynamic configurations is presented and examples and typical running times of various types of configurations are provided.
Abstract: Computer program for estimating subsonic aerodynamic characteristics of various aerodynamic configurations is presented. Program represents lifting planforms with vortex-lattice. Specific aerodynamic characteristics to be determined are described. Examples and typical running times of various types of configurations are provided.
126 citations
TL;DR: The effect of applying driving and retarding torques to the wing was studied in this paper, where a wing was mounted in a 5 × 7 ft low-speed wind tunnel and the measurements consisted of the unsteady lift, drag, angular acceleration and the wing rotation rate.
Abstract: The autorotation of a flat plate about its spanwise axis was experimentally studied Most of the work was done with a wing mounted in a 5 x 7 ft low-speed wind tunnel The measurements consisted of the unsteady lift, drag, angular acceleration and the wing rotation rate The flow pattern was very different from that over a static wing The maximum and average lift, drag and angular acceleration were measured for Reynolds numbers from 25,000 to 250,000 The effect of applying driving and retarding torques to the wing was studied A variety of wing configurations were tested, together with freely falling wings For Reynolds numbers above 4000 the average lift and drag coefficients were comparable to those observed in the fixed axis tests, and it appeared that the flow pattern was similar
120 citations
01 Mar 1971
107 citations
TL;DR: In this article, the performance of a number of silencer components, e.g., area discontinuities, branched systems, was measured in a very noisy exhaust system and compared with those predicted by the one-dimensional linearized theory with mean gas flow.
102 citations
01 Mar 1971
TL;DR: In this article, the effects of jet to free-stream dynamic pressure ratio effects on penetration and mixing of hydrogen injected normal to supersonic airstreams were investigated. But the authors focused on the effect of the pressure ratio on the mixture of hydrogen and fuel.
Abstract: Jet to free-stream dynamic pressure ratio effects on penetration and mixing of hydrogen injected normal to supersonic airstreams
101 citations
01 May 1971
TL;DR: Stress intensity factor calculated for cracked sheet with riveted and uniformly spaced stringers in this article, where the stringers are uniformly spaced and the rivets are riveted with uniformly spaced strings.
Abstract: Stress intensity factor calculated for cracked sheet with riveted and uniformly spaced stringers
01 Sep 1971
TL;DR: Mixing of hydrogen downstream from multiple injectors normal to supersonic jet flow for SU-personic combustion on ramjet engines was studied in this paper, where it was shown that the mixture of hydrogen and fuel can improve the performance of the ramjet engine.
Abstract: Mixing of hydrogen downstream from multiple injectors normal to supersonic jet flow, for supersonic combustion on ramjet engines
TL;DR: In this paper, the prediction techniques for the calculation of sonic booms produced by rather complex conventional supersonic aircraft designs performing level nonaccelerated flight in a quiet atmosphere are reviewed.
Abstract: Within the past two decades, the combined contributions of scientists and engineers in this country and abroad have resulted in development of systematic and reliable methods for the prediction of sonic‐boom phenomena. The prediction techniques reviewed in the present paper permit the calculation of sonic booms produced by rather complex conventional supersonic aircraft designs performing level nonaccelerated flight in a quiet atmosphere. It has been found that the calculated characteristics for a quiet atmosphere are representative of nominal conditions in a statistical sense for a real atmosphere. Basic concepts of supersonic flow analysis, for representation of an airplane as a linear distribution of disturbances and for determination of the resultant pressure field complete with shocks, are outlined. Numerical techniques for implementation of the theory are discussed briefly, and examples of the correlation of theory with experimental data from wind tunnel and flight tests are presented. Special attention is given to presentation of a simplified method for rapid “first‐cut” estimation of farfield bow‐shock overpressure. Finally, some problems encountered in attempts at applying the prediction techniques for the nearfield at high supersonic Mach numbers are recognized, and the need for further refinement of present techniques or the development of new systems is discussed.
TL;DR: In this article, the authors used UV absorption spectroscopy in shock tube studies to study the initiation of hydrogen-oxygen at 1200-1800 K, using UV absorption spectrum.
TL;DR: Nongray absorption and radiation cooling on smooth symmetric blunt bodies included in modified Maslen flow field method for radiation and large blowing as mentioned in this paper, which is used for radiation removal.
Abstract: Nongray absorption and radiation cooling on smooth symmetric blunt bodies included in modified Maslen flow field method for radiation and large blowing
01 Nov 1971
TL;DR: The far-field potential for both lifting and nonlifting three-dimensional wings at transonic speeds is developed herein for a subsonic free stream and could be used for a three- dimensional-wing computation similar to the computation made for the two-dimensional wing.
Abstract: The problem of determining the small-disturbance flow about two-dimensional airfoils at transonic speeds has been successfully treated by the process of matching a numerical solution of the near field to analytic expressions for the far field. The three-dimensional problem, it would appear, can be treated in a similar way with the aid of algorithms adapted to high-speed and high-capacity computers. The far-field potential for both lifting and nonlifting three-dimensional wings at transonic speeds is developed herein for a subsonic free stream. This potential could be used for a three-dimensional-wing computation similar to the computation made for the two-dimensional wing.
TL;DR: In this article, a theory for discrete frequency sound radiation from rotating periodic sources is described, which is quite general and can be applied to electromagnetic as well as acoustic radiation, and is basically developed for rotor noise and attempts to cover tonal noise generally from the whole family of rotors.
01 Aug 1971
TL;DR: Numerical solution of flow equations for laminar, transitional, and turbulent compressible boundary layers for planar or axisymmetric flows is given in this paper, where the boundary layers are assumed to be planar.
Abstract: Numerical solution of flow equations for laminar, transitional, and turbulent compressible boundary layers for planar or axisymmetric flows
01 Jan 1971
TL;DR: In this paper, Al alloy panels stiffened with bolted and integral stringers were used to determine stress intensity factor/crack growth rate relationship, and the relationship between stress intensity and crack growth rate was analyzed.
Abstract: Fatigue crack propagation in Al alloy panels stiffened with bolted and integral stringers, determining stress intensity factor/crack growth rate relationship
TL;DR: Thin shell isotropic clamped free elliptical cylindrical shells with various cross-sectional eccentricities, measuring frequencies and mode shapes by vibration analysis as mentioned in this paper, were used to measure frequency and mode shape.
Abstract: Thin shell isotropic clamped free elliptical cylindrical shells with various cross sectional eccentricities, measuring frequencies and mode shapes by vibration analysis
TL;DR: In this article, it was shown that a unique relationship exists between rms sound pressure level and transition Reynolds number, provided all other parameters are held nearly invariant, and that some facility characteristic has a strong influence on the transition Reynolds numbers.
Abstract: Description of additional results indicating that a unique relationship exists between rms sound pressure level and transition Reynolds number, provided all other parameters are held nearly invariant. The results illustrate the different levels of the transition Reynolds numbers obtained in six facilities with nearly invariant laminar boundary layers on the different models (at the same local unit Reynolds number) and indicate that some facility characteristic has a strong influence on the transition Reynolds numbers.
TL;DR: In this article, the authors used pitot, hot wire, wall pressure fluctuation and static pressure measurements for free stream Mach number estimation, using pitot and hot wire for the Nozzle wall hypersonic turbulent boundary layers.
Abstract: Nozzle wall hypersonic turbulent boundary layers at free stream Mach number, using pitot, hot wire, wall pressure fluctuation and static pressure measurements
TL;DR: In this article, the authors provide a general technical background for the problems of noise due to rotating blades and present a bibliography of some of the more recent work in the areas of rotor and propeller noise, compressor and fan noise, and duct acoustics.
01 Aug 1971
TL;DR: Starting phenomena of two-dimensional hypersonic inlets with turbulent intake boundary layers at free stream Mach 6 as mentioned in this paper, where the boundary layers are divided into two dimensions: 1D and 2D.
Abstract: Starting phenomena of two-dimensional hypersonic inlets with turbulent intake boundary layers at free stream Mach 6
TL;DR: In this article, double-exposure holographic interferometry was used to record the propagation of transverse waves in a plate and plots of the transverse displacement vs. distance from the center of impact were obtained.
Abstract: The technique of double-exposure holographic interferometry was used to record the propagation of transverse waves in a plate. The waves were initiated by striking the plate in the center with a ballistic pendulum; this technique produced axisymmetric response of the plate. Several pulsed-laser interferograms were obtained, each of which showed the bending wave at a different time after the initiation of impact. From the interferograms, plots of the transverse displacement vs. distance from the center of impact were obtained. The experimental data compared favorably with analytical results for the problem.
01 Jan 1971
TL;DR: The effect of injectant molecular weight on mixing of normal jet in Mach 4 airstream is discussed in this paper, where the authors present tables and graphs for the effects of molecular weights on mixing.
Abstract: Effect of injectant molecular weight on mixing of normal jet in Mach 4 airstream - tables and graphs
TL;DR: Plasma diagnostic data from onboard Langmuir probes, reflectometers, antenna VSWR and beacon and telemetry attenuation for blunt body reentry flow field was collected by as discussed by the authors.
Abstract: Plasma diagnostic data from onboard Langmuir probes, reflectometers, antenna VSWR and beacon and telemetry attenuation for blunt body reentry flow field
TL;DR: In this article, the major computer programs in existence for the analysis of shells of revolution by numerical integration and finite difference procedures are summarized and extensions of these programs which are currently underway and some of the primary assets of both the numerical integrator and finite-difference procedures are discussed.
01 Apr 1971
TL;DR: In this paper, the authors predict aerodynamic characteristics of arrow, delta, and diamond wing platforms using Prandtl-Glauert transformation for predicting the flight characteristics of a single-winged aircraft.
Abstract: Predicting aerodynamic characteristics of arrow, delta, and diamond wing platforms using Prandtl-Glauert transformation
01 Jan 1971
TL;DR: Data from 90-day manned test of regenerative life support system in space station simulator is used in this paper, where the regenerative system was tested on the International Space Station.
Abstract: Data from 90-day manned test of regenerative life support system in space station simulator