Download or read book Measurement of Cavity Shapes Above Ventilated Hydrofoils written by R. J. Altmann and published by . This book was released on 1965 with total page 90 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent test programs indicate that theoretical streamlines above a supercavitating hydrofoil may be considerably higher than those actually generated. To check theoretical predictions a three-dimensional traversing probe was constructed and used to map the upper cavity surfaces generated by two different two-dimensional hydrofoils. Experimental contours were found to fall below those predicted by theory at all angles of attack and depths of submergence tested. The rate of change of cavity ordinates with changes in angle of attack or depth of submergence is about the same as that predicted by theory. The contribution of angle of attack to cavity shape is responsible for the greater part of the difference between theoretical and measured cavity shapes. (Author).

Download or read book Effects of Ambient Conditions the Gravity Field and Struts on Flows Over Ventilated Hydrofoils written by R. Altmann and published by . This book was released on 1967 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt: A series of experiments was conducted to determine the effects on foil performance of changes in cavity pressure and submergence depth. With fully-ventilated foils, drag and lift coefficients were found to be proportional to (1 + sigma sub cav), as predicted by theory. For base-ventilated foils a different and unexpected dependence of drag and lift on the cavity cavitation number was observed. Lift and drag on fully ventilated hydrofoils were also found to be almost unaffected by changes in submergence depth over the range of practical interest, as predicted by theory. However, the magnitudes of the measured forces were found to be smaller than predicted values. A simple analysis was made of the possible effects of the gravity field on foil performance. Further support for the idea that the gravity field may exert considerable influence was obtained through a series of tests in which ventilated hydrofoils were operated at both positive and negative angles of attack. Measurements were also made to determine the effects of struts on ventilated hydrofoil cavity contours. Indirectly, these tests also assessed the magnitude of the strut-induced downwash. A considerable downwash was found to exist, having a profound effect on the cavity shape over the hydrofoil. Recent linearized theory on the magnitude of this strut-induced downwash correlates very well with the measurements. (Author).

Download or read book Unsteady Force and Cavity Characteristics for Ventilated Hydrofoils written by J. M. Wetzel and published by . This book was released on 1967 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental measurements were made of the unsteady cavity and force characteristics for both forced and naturally ventilated hydrofoils of finite span submerged below a free surface. Unsteady cavity characteristics were studied for a force-ventilated wedge subjected to a sudden change in either the air flow rate to the cavity or angle of attack. Differences were observed in air entrainment rates measured for the unsteady case as compared to the corresponding instantaneous steady case. The magnitude of the differences depended on the kind of unsteadyness introduced. Unsteady force characteristics were determined for naturally ventilated foils undergoing either a sinusoidal heaving motion or a harmonic oscillation of a trailing edge flap. The amplitude of the oscillatory lift was found to increase with increasing reduced frequency for a heaving foil, whereas the oscillatory lift was essentially constant up to reduced frequencies of 1.2 for the foil with an oscillating flap. There is limited agreement of the data with available theory. (Author).

Download or read book Linearized Theory of Cavity Flow Past a Hydrofoil of Arbitrary Shape written by Tatsuro Hanaoka and published by . This book was released on 1967 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Cavity Shape Characteristics for Supercavitating Hydrofoils written by S. A. Kinnas and published by . This book was released on 1984 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work the problem of a supercavitating hydrofoil in linear theory is stated in terms of integral equations of unknown vortex and cavity source distributions. The general problem is composed into the camber, the thickness and the angle of attack problems. For each problem the solution is expressed in terms of integrals of the slope of the lower surface of the hydrofoil weighted by known functions. The numerical scheme to compute those integrals has been proved very accurate and insensitive to the variables of the problem. As an application, tables and some cavity plots are given for the NACA a=0.8 meanline series and the NACA Four-digit Wing Sections thickness forms. Keywords: Cavitation; Cavity shape.

Download or read book Experimental Investigation of Forced Ventilated Cavities on Hydrofoils of Various Chord Lengths and Planforms written by Robert L. Waid and published by . This book was released on 1968 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental program was conducted in the Lockheed underwater missile facility to determine the effects of velocity, ambient pressure and model parameters on the characteristics of forced ventilated cavities. The lift and drag forces and airflow requirements were determined for submerged hydrofoils of aspect ratio 3:1 with rectangular, tapered and triangular planforms. Also determined was the cavity length, vortex core size, reentrant jet penetration, and size of the shed wake. The dominance of the reentrant jet mixing on the entrainment rate for a wide range of ventilation coefficients is illustrated.

Download or read book Experimental Determination of the Forces on Supercavitating Hydrofoils with Internal Ventilation written by N. L FICKEN (Jr) and published by . This book was released on 1963 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: An investigation is in progress to develop techniques for using internal ventilation to produce very low cavitation numbers at low and moderate speeds. A nondimensional coefficient, the ventilation index, was defined. It was found that the cavitation number based on measured cavity pressure behaves differently for ventilated flows at speeds in the supercavitating regime and at speeds in the subcavitating regime. In both cases, however, the measured cavitation number is related directly to the ventilation index and is relatively insensitive to angle of attack. At high values of the ventilation index (about 0.19 for tests of the 5-term foil reported), the lift and drag coefficients become constant at values appropriate to zero cavitation number. Methods for relating the lift and drag coefficients for various ventilating airflow rates to the appropriate cavitation number are presented for the two speed ranges. Discrepancies exist between the results obtained from high- and low-speed ventilated tests. (Author).

Download or read book U S Government Research Development Reports written by and published by . This book was released on 1966-11 with total page 1014 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1976 with total page 1072 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Government wide Index to Federal Research Development Reports written by and published by . This book was released on 1966-11 with total page 1080 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Technical Abstract Bulletin written by and published by . This book was released on with total page 776 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book U S Government Research Reports written by and published by . This book was released on 1964 with total page 1600 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Proceedings written by and published by . This book was released on 1975 with total page 752 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1972 with total page 542 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Defense Industry Bulletin written by and published by . This book was released on 1967 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Government Reports Announcements written by and published by . This book was released on 1972-05-10 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Hydraulic Machinery and Cavitation written by Enrique Cabrera and published by Springer. This book was released on 2015-02-27 with total page 1210 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydraulic machinery such as turbines and pumps is widely used around the world. Related topics concerning design, operation and maintenance are of relevant interest. In this context, cavitation is a phenomenon to be taken into account, and this was treated in the XVIII IAHR Symposium on Hydraulic Machinery and Cavitation which took place in Valencia, Spain, 16th-19th September, 1996 and which was hosted by the Polytechnic University of Valencia. The proceedings of the Symposium have been published in two volumes. In this first volume, the papers included cover the following topics: Hydraulic Turbines, Analysis and Design Hydraulic Pumps Hydraulic Elements, Dynamic Characterization and Hydraulic Behaviour Cavitation and Sand Erosion In the second volume, the papers included cover the following topics: Hydraulic Transients and Control Systems Related to Hydraulic Machinery and Plants Oscillatory and Vibration Problems in Hydraulic Machinery and Power Stations Experimental Investigations related to Hydraulic Machinery and its Applications Practical Applications of the Hydraulic Machinery Monitoring, Predictive Maintenance and Refurbishment The 119 papers presented at the Symposium, from research groups, consulting companies and manufacturers, constitute an important collection for investigators, engineers and technicians who are interested in updated information on hydraulic machinery. This book is intended to be a reference text comprising the latest innovations on this subject.