摘要 :
The proof of the validity of the Reynolds law of similitude for the surface resistance of planes has been developed with an accuracy hitherto unattained and for a large range of lengths and speeds. It has been shown that, in addit...
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The proof of the validity of the Reynolds law of similitude for the surface resistance of planes has been developed with an accuracy hitherto unattained and for a large range of lengths and speeds. It has been shown that, in addition to the form resistance, the resistance of the longitudinal edges must be taken into account.
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摘要 :
In general, the available literature presents only the limited aspects of similitude requirements and scaling relationships pertinent to each reported investigation. There is a need, however, for a comprehensive review of the adva...
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In general, the available literature presents only the limited aspects of similitude requirements and scaling relationships pertinent to each reported investigation. There is a need, however, for a comprehensive review of the advantages and limitations of wind-tunnel and free-flight model testing techniques with regard to similitude requirements, test objectives, and comparison of model and full-scale results.
This report reviews the similitude requirements for the most general test conditions. These similitude requirements are then considered in relation to the scaling relationships, test technique, test conditions (including supersonic flow) , and test objectives. Particular emphasis is placed on satisfying the various similitude requirements for incompressible and compressible flow conditions. For free-flying model tests, the test velocities for incompressible flow are scaled from Froude number similitude requirements and those for compressible flow are scaled from Mach number similitude requirements. Finally, the limitations of various test techniques are indicated, with emphasis on the free-flying model.
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摘要 :
The laws of comparison of dynamically similar fluid motions are derived by three different methods based on the same principle and yielding the same or equivalent formulas. This report outlines the three current methods of compari...
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The laws of comparison of dynamically similar fluid motions are derived by three different methods based on the same principle and yielding the same or equivalent formulas. This report outlines the three current methods of comparing dynamically similar motions, more especially of fluids, initiated respectively by Newton, Stokes (or Helmholtz), and Rayleigh. These three methods, viz., the integral, the differential, and the dimensional, are enough alike to be studied profitably together. They are treated in succession then compared. (author)
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The aged double-skin-plate valves of the Eisenhower and Snell Locks on the St. Lawrence Seaway are being replaced. The replacement valves are of the vertical-frame design to facilitate inspection and spot repair. A new vertical-fr...
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The aged double-skin-plate valves of the Eisenhower and Snell Locks on the St. Lawrence Seaway are being replaced. The replacement valves are of the vertical-frame design to facilitate inspection and spot repair. A new vertical-frame valve was installed in the filling valve well of the Snell Lock s south wall culvert. The new vertical-frame valve operated at a slower rate than the double-skin-plate valve, and its operation required more energy. A physical model study was conducted to identify modifications that could be made to reduce the energy required to operate the new valve. The recommended valve design had a top plate that was only large enough to serve as a base for the stabilizers and strut connector. The bottom plate and bottom seal was replaced with a sharp-edged lip formed at the bottom end of the ribs and skin plate. The recommended valve was specifically designed to fit the Eisenhower and Snell Locks, it meets the USACE guidance for verticalframe valves, and it had hoist forces that were lower than the valves currently in operation.
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Scale models were developed for aeroelastic research, including external stores and flutter active supression areas. The specific design of a C-101 wing model is detailed. The design is based on the application of similitude laws....
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Scale models were developed for aeroelastic research, including external stores and flutter active supression areas. The specific design of a C-101 wing model is detailed. The design is based on the application of similitude laws. The list of mass distribution required in the different segments is given. Drawings are presented.
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Similarity parameters are developed which govern the length of non-equilibrium zones behind normal shock waves. Non-equilibrium effects produced by both vibrational relaxation and dissociation are considered. The parameters can al...
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Similarity parameters are developed which govern the length of non-equilibrium zones behind normal shock waves. Non-equilibrium effects produced by both vibrational relaxation and dissociation are considered. The parameters can also account for arbitrary levels of free-stream vibra-tional energy or dissociation level.
The validity of the parameters is examined using numerical computations of the properties of the non-equilibrium fields. These computations are made with the aid of experimental1y based rate expressions.
The parameters, when written in a form describing the variation of non-equilibrium zone length with Mach number, are shown to have acceptable accuracy.
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摘要 :
A systematic study is made of the approximate inviscid theory of thin bodies moving at such high supersonic speeds that nonlinearity is an essential feature of the equations of flow. The first-order small-disturbance equations are...
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A systematic study is made of the approximate inviscid theory of thin bodies moving at such high supersonic speeds that nonlinearity is an essential feature of the equations of flow. The first-order small-disturbance equations are derived for three-dimensional motions involving shock waves, and estimates are obtained for the order of error involved in the approximation. The hypersonic similarity rule of Tsien and Hayes, and Hayes' unsteady analogy appear in the course of the development. It is shown that the hypersonic theory can be interpreted so that it applies also in the range of linearized supersonic flow theory. Several examples are solved according to the small-disturbance theory, and compared with the full solutions when available.
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