Dynamic stability of space vehicles. Structural dynamics model testing
Dimensional analysis, and similitude and scaling laws for structural dynamics model testing of spacecraft dynamic stability
Wissmann, J. W.↗
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Active function synthesis utilizing modeling and scaling procedures Final technical report, 1 Oct. 1968 - 30 Sep. 1969
Usefulness and effectiveness extension of dimensional analysis for modeling and scaling procedures by algorithms
Chen, W.-K.↗
Summary of the NASA-SRI Round Robin Ablation Program
NASA-SRI Round Robin Ablation Program summary, discussing dimensional analysis, Teflon, nylon and surface temperature
Clark, C. F.↗
Study of effects of design details on structural response to acoustic excitation
The normal mode vibration characteristics of one-dimensional and two-dimensional panel arrays were investigated analytically and experimentally. The finite element displacement method was used to formulate the structural models. The structural models include a stiffness and consistent mass matrix for thin-walled open-section beams not previously reported, and a modification of a rectangular plate bending element to include a fundamental interior mode for the element as a generalized coordinate. Provision for adding lumped masses to represent accelerometers is also included. For the one-dimensional panel, the normal mode stress resultants are obtained by integrating the equilibrium equations directly. For the two-dimensional panel arrays, the solution for the stress resultants in the cover sheet was attempted by introducing stress functions dependent upon the displacement field of the plate element. This approach, although incomplete, is a natural extension of the one-dimensional analysis for plate elements. The exerimental program which was used to verify the analysis is described and experimental results are compared with the analysis.
Rudder, F. F., Jr.↗
Wind tunnel balance system for determination of wind-induced vibrations of a rigid shuttle model in the launch configuration
A wind tunnel balance system was designed to determine the wind-induced vibrations of a space shuttle model. The balance utilizes a flexible sting mounting in conjunction with a geometrically scaled rigid model. Bending and torsional displacements are determined through strain-gauge-instrumented spring bar mechanisms. The natural frequency of the string-model system can be varied continuously throughout the expected scaled frequency range of the shuttle vehicle while a test is in progress by the use of moveable riders on the spring bar mechanism. Through the use of a frequency analyzer, the output can be used to determine troublesome vibrational frequencies. A dimensional analysis of the wind-induced vibration problem is also presented which suggests a test procedure. In addition a computer program for analytical studies of the forced vibration problem is presented.
Source record↗
Experimental investigation of two-phase heat transfer in a porous matrix.
One-dimensional two-phase flow transpiration cooling through porous metal is studied experimentally. The experimental data is compared with a previous one-dimensional analysis. Good agreement with calculated temperature distribution is obtained as long as the basic assumptions of the analytical model are satisfied. Deviations from the basic assumptions are caused by nonhomogeneous and oscillating flow conditions. Preliminary derivation of nondimensional parameters which characterize the stable and unstable flow conditions is given. Superheated liquid droplets observed sputtering from the heated surface indicated incomplete evaporation at heat fluxes well in access of the latent energy transport. A parameter is developed to account for the nonequilibrium thermodynamic effects. Measured and calculated pressure drops show contradicting trends which are attributed to capillary forces.
Von Reth, R.↗
Geometric similitude of lunar and terrestrial craters.
Application of an elementary technique of dimensional analysis, that of testing for geometric similitude, suggests an impact genesis for most lunar craters. Geometrically similar phenomena fulfill four requirements: (1) log-log plots of paired descriptive variables are linear, (2) slopes of these plots equal ratios of the dimensions of the two variables, (3) intercepts of the plots are the same and (4) phenomena belong to the same general taxonomic group. Five topographic criteria are used to test lunar and terrestrial craters for geometric similitude: the variation of rim diameter with (1) interior depth, (2) exterior rim height, (3) exterior rim width and (4) rim crest circularity, and (5) variation of exterior rim height with crater depth. By all criteria, fresh bowl-shaped lunar craters between 10 m and 20 km in diameter are geometrically similar to fresh terrestrial meteorite craters and craters produced by chemical and nuclear explosives at shallow depths of burial. Most lunar craters exceeding 10-20 km in diameter fulfill only the last three criteria of similitude.
Pike, R. J.↗
A problem in micropolar elasticity.
In this paper a three-dimensional analysis for statics and dynamics of a class of simply supported rectangular plates made up of micropolar elastic material is presented. The solution is in the form of series, in which each term is explicitly determined. For free vibrations, the frequencies are obtained by the solution of a closed form characteristic equation.
Srinivas, S.↗
Computer program for predicting off-design performance of centrifugal compressors
Complete knowledge of compressor overall geometry and working fluid total inlet conditions is required for program's use. On given speed line, compressor performance is calculated for range of inlet velocity levels. Working fluid state conditions and flow properties are calculated using mean stream line one-dimensional analysis.
Galvas, M. R.↗
Fluid dynamics and kinematics of molten metals in the low-gravity environment of Skylab
The response of molten metals to mechanical and thermal driving forces in nominal and microgravity is analyzed both theoretically and experimentally. The magnitude and transient behavior of internal fluid circulations, surface deformations, and globule trajectories and their effects on solidification in the Skylab electron beam sphere forming and metals melting experiments are determined. The theoretical approach consists of dimensional analysis of the governing differential equations. Experimental aspects include evaluation of specimens from terrestrial, KC-135 research aircraft, and actual Skylab tests and analysis of high speed movies taken during the melting processes. Several gravity variations and gravity independent results were successfully predicted based on expected differences and similarities in fluid dynamics.
Bourgeois, S. V.↗
Instrument to measure energy and charge of low energy interplanetary particles
An experiment to measure the charge composition and energy spectra of ultra low energy charged particles in interplanetary space has been developed and launched on the IMP 8 (Explorer 50) satellite on Oct. 26, 1973. The instrument consists of two separate sensors sharing common electronics. One of these sensors uses a thin window gas proportional counter to measure the rate of energy loss and a totally depleted silicon surface barrier detector to measure total energy of incoming particles. The energy range for two dimensional analysis extends from 300 KeV to 2.5 MeV for protons and 60 KeV/nucleon to 25 MeV/nucleon for iron with excellent resolution of individual chemical elements. The other sensor combines electrostatic deflection with total energy measurements in silicon surface barrier detectors to give the ionic charge and kinetic energy of the particle.
Tums, E.↗
On the propagation velocity of a detonation-shock combined wave
A quasi-one-dimensional analysis and a generalized Chapman-Jouguet condition are developed for a gaseous free detonation in an inert environment. Two characteristic features derived from the results are that there exists a lower limit on the heat of combustion, the charge diameter, and the molecular weight of the ambient gas and that there are two propagation velocities for a parameter combination above a certain critical value. Therefore the detonation failure of a free gas column is a hydrodynamic rather than a chemical phenomenon.
Tsuge, S.↗
Observations of Jupiter at 26.3 MHz using a large array
A 640 element phase-steerable dipole array has been used to make highly sensitive observations of the planet Jupiter during the 1973 apparition. The satellite Io is found to have very little influence at the low flux levels, whereas the definition of sources A and B appears to be relatively flux independent. A two-dimensional analysis of the data in the Jupiter-Io plane has revealed considerable source B activity at low intensities which is not influenced by Io.
Desch, M. D.↗
Study on steady state wind and turbulence environments
The structure of wakes and how this structure is related to the size and shape of buildings and other obstacles, and to ambient winds, was investigated. Mean values of natural atmospheric flow were obtained and used in conjunction with theoretical relationships developed by dimensional analysis to establish a model of the flow in the wake. Results indicate that conventional and V/STOL aircraft passing through the wake during takeoff and landing would experience not only a change in turbulence level, but also a change in mean wind speed of a magnitude roughly equivalent to that of the eddy components.
Brundidge, K. C.↗
Terrestrial analogs of the Hellespontus dunes, Mars
Geomorphic features in the Hellespontus region, Mars, were compared with dunes of the crescentic ridge type in numerous terrestrial sand seas quantitatively by dimensional analysis of dune lengths, widths, and wavelengths. Mean values for the Hellespontus dunes are close to mean values derived from measurements of all sampled terrestrial sand seas. Terrestrial analogs of form and areal distribution of the Hellespontus dunes are shown by comparison of scale ratios derived from the measurements. Dunes of similar form occur in South West Africa, in Pakistan, in the southeastern Arabian peninsula, in the Sahara, in eastern USSR and northern China, and in western North America. Terrestrial analogs closest to form and areal distribution of the Hellespontus dunes are in the Kara Kum Desert, Turkmen SSR, and in the Ala Shan (Gobi) Desert, China.
Breed, C. S.↗
Wave propagation in laminated orthotropic circular cylindrical shells
An exact three-dimensional analysis of wave propagation in laminated orthotropic circular cylindrical-shells is developed. Numerical results are presented for three-ply shells, and for various axial wave lengths, circumferential wave numbers, and thicknesses. Results from a thin shell theory and a refined approximate theory are compared with the exact results.
Srinivas, S.↗
An estimate of mean flow properties in a turbulent diffusion flame
Turbulent diffusion flames were computed while neglecting fluctuations of density, concentration and temperature, with reference to a central hydrogen jet issuing into a parallel coaxial airstream. An estimate for the time-average rate of fuel consumption was made, based mainly on dimensional analysis.
Bangert, L. H.↗
Manufacture of astroloy turbine disk shapes by hot isostatic pressing, volume 1
The Materials in Advanced Turbine Engines project was conducted to demonstrate container technology and establish manufacturing procedures for fabricating direct Hot Isostatic Pressing (HIP) of low carbon Astroloy to ultrasonic disk shapes. The HIP processing procedures including powder manufacture and handling, container design and fabrication, and HIP consolidation techniques were established by manufacturing five HIP disks. Based upon dimensional analysis of the first three disks, container technology was refined by modifying container tooling which resulted in closer conformity of the HIP surfaces to the sonic shape. The microstructure, chemistry and mechanical properties of two HIP low carbon Astroloy disks were characterized. One disk was subjected to a ground base experimental engine test, and the results of HIP low carbon Astroloy were analyzed and compared to conventionally forged Waspaloy. The mechanical properties of direct HIP low carbon Astroloy exceeded all property goals and the objectives of reduction in material input weight and reduction in cost were achieved.
Eng, R. D.↗