National Advisory Committee for Aeronautics (NACA) - 13,806 Matching Results

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The Interaction of a Reflected Shock Wave with the Boundary Layer in a Shock Tube

Description: Ideally, the reflection of a shock from the closed end of a shock tube provides, for laboratory study, a quantity of stationary gas at extremely high temperature. Because of the action of viscosity, however, the flow in the real case is not one-dimensional, and a boundary layer grows in the fluid following the initial shock wave. In this paper simplifying assumptions are made to allow an analysis of the interaction of the shock reflected from the closed end with the boundary layer of the initial shock afterflow. The analysis predicts that interactions of several different types will exist in different ranges of initial shock Mach number. It is shown that the cooling effect of the wall on the afterflow boundary layer accounts for the change in interaction type. An experiment is carried out which verifies the existence of the several interaction regions and shows that they are satisfactorily predicted by the theory. Along with these results, sufficient information is obtained from the experiments to make possible a model for the interaction in the most complicated case. This model is further verified by measurements made during the experiment. The case of interaction with a turbulent boundary layer is also considered. Identifying the type of interaction with the state of turbulence of the interacting boundary layer allows for an estimate of the state of turbulence of the boundary layer based on an experimental investigation of the type of interaction. A method is proposed whereby the effect of the boundary-layer interaction on the strength of the reflected shock may be calculated. The calculation indicates that the reflected shock is rapidly attenuated for a short distance after reflection, and this result compares favorably with available experimental results.
Date: March 1, 1958
Creator: Mark, Herman
Partner: UNT Libraries Government Documents Department

Investigation of Aperiodic Time Processes with Autocorrelation and Fourier Analysis

Description: Autocorrelation and frequency analyses of a series of aperiodic time events, in particular, filtered noises and sibilant sounds, were made. The position and band width of the frequency ranges are best obtained from the frequency analysis, but the energies contained in the several bands are most easily obtained from the autocorrelation function. The mean number of zero crossings of the time function was determined from the curvature of the latter function in the vicinity of the zero crossing, and also with the aid of a decimal counter. The second method was found to be more exact.
Date: March 1, 1958
Creator: Exner, Marie Luise
Partner: UNT Libraries Government Documents Department

Effects of surface roughness and extreme cooling on boundary-layer transition for 15 degrees cone-cylinder in free flight at Mach numbers to 7.6

Description: Report presenting an investigation of three cone-cylinder bodies to obtain boundary-layer-transition data at very low ratios of wall to local stream temperature. Surface finishes at several levels of roughness height were tested. Results regarding the smooth body and rough bodies are provided.
Date: March 5, 1958
Creator: Rabb, Leonard & Krasnican, Milan J.
Partner: UNT Libraries Government Documents Department

An Investigation of the Free-Spinning and Recovery Characteristics of a 1/24-Scale Model of the Grumman F11F-1 Airplane with Alternate Nose Configurations with and without Wing Fuel Tanks, TED No. NACA AD 395

Description: A supplementary investigation has been conducted in the langley 20-foot free-spinning tunnel on a l/24-scale model of the Grumman F11F-1 airplane to determine the spin and recovery characteristics with alternate nose configurations, the production version and the elongated APS-67 version, with and without empty and full wing tanks. When spins were obtained with either alternate nose configuration, they were oscillatory and recovery characteristics were considered unsatisfactory on the basis of the fact that very slow recoveries were indicated to be possible. The simultaneous extension of canards near the nose of the model with rudder reversal was effective in rapidly terminating the spin. The addition of empty wing tanks had little effect on the developed spin and recovery characteristics. The model did not spin erect with full wing tanks. For optimum recovery from inverted spins, the rudder should be reversed to 22O against the spin and simultaneously the flaperons should be moved with the developed spin; the stick should be held at or moved to full forward longitudinally. The minimum size parachute required to insure satisfactory recoveries in an emergency was found to be 12 feet in diameter (laid out flat) with a drag coefficient of 0.64 (based on the laid-out-flat diameter) and a towline length of 32 feet.
Date: March 5, 1958
Creator: Bowman, James S., Jr.
Partner: UNT Libraries Government Documents Department

Investigation of a high-flow transonic-compressor inlet stage having a hub-tip radius of 0.35

Description: Report discussing testing on a high-thrust turbojet engine capable of operation at high flight speeds. The report presents the overall performance and blade-element performance of the engine at a specified hub-tip radius ratio and specific weight flow of air.
Date: March 6, 1958
Creator: Felix, A. Richard
Partner: UNT Libraries Government Documents Department

Investigation of the longitudinal aerodynamic characteristics of a trapezoidal-wing airplane model with various vertical positions of wing and horizontal tail at Mach numbers of 1.41 and 2.01

Description: Report presenting an investigation in the supersonic pressure tunnel to determine the effects of various vertical positions of a wing and horizontal tail on the static longitudinal aerodynamic characteristics of a trapezoidal wing model. Results regarding effect of wing vertical position and tail-on characteristics are provided.
Date: March 6, 1958
Creator: Foster, Gerald V.
Partner: UNT Libraries Government Documents Department

Supersonic Wave Interference Affecting Stability

Description: Some of the significant interference fields that may affect stability of aircraft at supersonic speeds are briefly summarized. Illustrations and calculations are presented to indicate the importance of interference fields created by wings, bodies, wing-body combinations, jets, and nacelles.
Date: March 8, 1958
Creator: Love, Eugene S.
Partner: UNT Libraries Government Documents Department