Parallel Jets Research Articles

The ''fountain effect'' and VTOL exhaust ingestion.

This paper presents the results of an experimental study of the ingestion and flowfield characteristics of the interaction of two parallel jets of heated air, a quiescent environment, a perpendicular plane, and a pair of inlets. The flowfield was observed visually, and the transient response of the inlet thermocouples was recorded on an oscillograph over a range of configuration and flow parameters, e.g., spacing ratios, angles, and velocities. The major contribution of this study is the obtaining of a detailed qualitative picture of the upwash flowfield and its relation to ingestion levels. Data were obtained also with the image technique (and with the addition of simulated fuselage and wings to better approximate a VTOL aircraft). Some apparent discrepancies between previous full-scale and small-scale VTOL exhaust ingestion tests are explained. This study also points out that inlet temperature fluctuations are a random process and that a statistical approach to data analysis is desirable. No menclature D = nozzle diameter / = frequency of temperature fluctuation H = nozzle height above ground plane NPR = nozzle pressure ratio (= nozzle pressure/atmospheric pressure) S = distance between nozzle exit centers AT = inlet temperature rise above ambient ATm = time mean of AT 7 ATy = exhaust jet temperature minus ambient temperature V = jet exit velocity a = nozzle cant angle |8 = ground plane inclination

The Interference of Two-Dimensional Parallel Jets : 1st Report Experiments on Dual Jet

The Interference of Two-Dimensional Parallel Jets : 1st Report Experiments on Dual Jet

Untersuchungen an einem Überschallplasmastrahl mit axialem Strom

Starting from a parallel jet concept the linearized magnetogasdynamic equations are solved for a supersonic free plasma jet with an axial current. The solution is given in terms of the magnetic pressure number. A critical magnetic pressure number depending on the MACH number is derived. Below this value standing periodic pressure waves occur, as in the gasdynamic case. For higher values the pressure distribution is non-periodic. Experiments are performed with a supersonic argon jet. The MACH number is determined by the shock angle at a cone. The pressure distribution in the axis of the jet is measured by a pressure probe. The experimental results are consistent with the theoretical predictions.

Integrated solar pressure for a transparent balloon satellite

Reference 1 Lewis, C. H. and Carlson, D. J., Normal shock location in underexpanded gas and gas-particle jets, AIAA J. 2, 776-777 (1964). 2 D'Attorre, L. and Harshbarger, F., Experimental and theoretical studies of underexpanded jets near the Mach disc/ General Dynamics/Astronautics Kept. GDA-DBE-64-008 (February 1964). 3 D'Attorre, L. and Harshbarger, F., Further experimental and theoretical studies of underexpanded jets near the Mach disc, General Dynamics/Astronautics Rept. GDA/DBE-64-041 (July 1964). 4 D'Attorre, L. and Harshbarger, F., The behavior of the Mach disc up to moderate pressure ratios, General Dynamics/ Astronautics Rept. GD-DBE-64-042 (July 1964). 5 Foelsch, K., The analytical design of an axially symmetric laval nozzle for a parallel and uniform jet, J. Aeronaut. Sci. 16, 161-166 (1949). 6 Bowyer, J., D'Attorre, L., and Yoshihara, H., Transonic aspects of hypervelocity rocket plumes, Supersonic Flow, Chemical Processes and Radiative Transfer, edited by D. B. Olfe and V. Zakkay (Pergamon Press, Ltd., London, 1964), pp. 203-209. 7 Love, E. S., Grigsby, E. C., Lee, L. P., and Woodling, M. J., Experimental and theoretical studies of axisymmetric free jets, NASA TR R-6 (1959). Balloon

Breakup of liquid jets by transverse shocks

Multiple shock waves impinging on a single liquid jet and on two parallel jets in a direction perpendicular to their flow axes

On the characteristic method for unsteady compressible flow

The method of graphical computation based on the use of characteristics is easier to handle than the arithmetical computation for the study of unsteady flow problems. The possibility of reducing the equations for the characteristics into simple non-dimensional form gives the construction an accuracy comparable with the numerical computation. Regarding the results obtained by this method, it is necessary to verify by actual measurements on pipe flows and engine trials the validity of the simple assumptions made in the graphical computation. The success of the method indicates that it may be possible to use this procedure for the case of the parallel supersonic jet also. In fact the method of characteristics has been successfully employed in the design of a parallel flow jet in some recent work by R. Saurer5 and K. Foetsch.6

The Analytical Design of an Axially Symmetric Laval Nozzle for a Parallel and Uniform Jet

The Analytical Design of an Axially Symmetric Laval Nozzle for a Parallel and Uniform Jet

The Conversion of the Stanton 3-Inch High-Speed Wind Tunnel to the Open Jet Type

The 3-inch high-speed wind tunnel developed by Stanton has been converted in the Engineering Department of the National Physical Laboratory to the open jet principle, the working jet now being contained in a square glass-sided chamber. The pressure in the observation chamber can be controlled within certain limits by altering the axial length of the gap between the inlet and outlet, and the presence of standing waves in the jet can be largely eliminated by bringing the chamber pressure to a value equal to that in the jet at the chamber inlet. In place of the divergent jet used by Stanton, an approximately parallel working jet has been obtained in the modified tunnel by using inlet nozzles with profiles determined by a graphical construction based on the “characteristic curve” method given by Busemann. An optical system has also been fitted enabling Schlieren photographs of the flow pattern to be obtained. Measurements of the wave systems set up round model cones indicate agreement with the theory established by Taylor and Maccoll which they found to accord with the results of larger-scale firing trials on conical-headed shell, thus providing evidence of the close similarity between conditions in the tunnel and on the full scale.

A Large French Wind Tunnel

THE large wind tunnel which has just been completed at Chalais-Meudon is of considerable interest. It is the second tunnel capable of testing a full-sized aeroplane to be constructed, the first being the 60 ft. x 30 ft. tunnel at Langley Field, U.S.A., and it differs in one very important respect from any other wind tunnel, in that it is built in the open. In general design it is not unlike the tunnel built by Eiffel in 1912 at Auteuil; a type now generally known by his name. Air is drawn in through a contracting inlet and then passes as a parallel free jet across the observation chamber into a collector cone in which a gradual expansion takes place in order to recover most of the kinetic energy of the stream.

The Parallel Jet High Vacuum Pump

The Parallel Jet High Vacuum Pump

The Parallel Jet High Vacuum Pump

The Parallel Jet High Vacuum Pump