bluuebunny/crossref_metadata_2025_split huggingface dataset:
Supersonic flow investigations with a “hydraulic analogy” water channel
Authors: Black Joseph , Mediratta O. P. 
Published: July 2016

SummmaryThis paper describes the construction of a water channel in the University of Bristol for the investigation of the analogy between the two-dimensional flow of a gas and that of shallow water with a free surface. Both continuous and discontinuous flow were examined, with a view to determining the limitations of the analogy.Continuous “ shooting “ water flow was found to be reasonably analogous with supersonic isentropic gas flow, a static depth of about half an inch appearing to be satisfactory with this particular channel. No independent check was made of the agreement, or otherwise, between “streaming” water flow and subsonic gas flow, since the method of checking used was the measurement of the angle of the waves formed on the water surface, and such waves exist only in “ shooting” flow.
Contracting ducts of finite length
Authors: Whitehead L. G. , Wu L. Y. , Waters M. H. L. 
Published: July 2016

SummmaryA method of design is given for wind tunnel contractions for two-dimensional flow and for flow with axial symmetry. The two-dimensional designs are based on a boundary chosen in the hodograph plane for which the flow is found by the method of images. The three-dimensional method uses the velocity potential and the stream function of the two-dimensional flow as independent variables and the equation for the three-dimensional stream function is solved approximately. The accuracy of the approximate method is checked by comparison with a solution obtained by Southwell's relaxation method.In both the two and the three-dimensional designs the curved wall is of finite length with parallel sections upstream and downstream. The effects of the parallel parts of the channel on the rise of pressure near the wall at the start of the contraction and on the velocity distribution across the working section can therefore be estimated.
The Symmetric Vibrations of Aircraft
Authors: Traill-Nash R. W. 
Published: July 2016

SummaryThe eigenvalue equations for symmetric vibration of a complete aircraft are derived in a very general form. The “lumped mass” approximation to the continuous mass distribution is used and sub-matrices are associated with properties of relatively simple branches of the system. The final eigenvalue equations are expressed in terms of these sub-matrices, so that in a numerical application the physical system, as such, is considered only in relation to the properties of the simple branches. It is assumed initially that the aircraft wing and tail have flexural axes of the conventional type, but it is shown in the Appendix that under certain conditions the treatment can be generalised to cover swept and cranked wing aircraft.
The Flow of an Incompressible Fluid through an Axial Turbo-Machine with any Number of Rows
Authors: Railly J. W. 
Published: July 2016

SummaryA method is described whereby, at any point in an infinite parallel annulus, the approximate axial velocity due to a single row of high aspect ratio blades may be calculated from a knowledge of the conditions of flow adjacent to the blades. The method is based on the assumption of a simplified expression for the radial velocity, being the product of an unknown function of the radius and an exponential term independent of the radius containing an undetermined constant; the function and the undetermined constant are calculated by reference to the conditions of flow in the plane of the row considered. The flow due to any number of rows is then obtained by summing the radial velocity fields due to each row and obtaining the axial velocities by integration of the equation of continuity.The solution of the problem with infinitely many rows is shown to have a simple form by virtue of the fact that the flow (provided that the velocities remain finite) settles down to a pattern which is periodic by one stage pitch.
A New Treatment of the Tuned Absorber with Damping
Authors: Johnson D.C. 
Published: July 2016

SummaryThe design of the damped tuned vibration absorber, which has previously been treated algebraically, is studied by the use of a three-dimensional admittance diagram. The advantages of this method are that the basic principles can be more easily understood and that it is not necessary to simplify the vibrating system so much. The results obtained by the use of the method show that under some conditions the algebraic treatment does not give the optimum tuning, but that the differences in performance of dampers which have been designed by the two methods will not be large. It is shown how the method may be extended to more complex problems.
The Sensitivity and Range Required in a Toepler Schlieren Apparatus for Photography of High-Speed Air Flow
Authors: Mair W. A. 
Published: July 2016

SummaryA simple theoretical analysis is given of the quantities affecting the sensitivity and range of a schlieren apparatus. In regions of large density gradient the deflections of the light rays may lie outside the normal working range. When this occurs, dark regions may appear in parts of the photograph that would normally be light. Examples of this effect are given, and it is shown that confusion can be avoided by taking photographs in pairs, with the knife edges or slits arranged to give sensitivities of opposite sign.The deflections of light rays in various typical disturbances in a supersonic air stream are calculated, using geometrical optics. Prandtl-Meyer expansions, boundary layers, and plane and curved shock waves are considered. From these calculated deflections it is shown that some of the anomalous effects commonly observed in schlieren photographs can be explained.
A Note on the Theory of the Constant-Area Mixing of Compressible Flows as Applied to High-Speed Wind Tunnel Design
Authors: Irving F. G. 
Published: July 2016

SummaryThe one-dimensional equations governing the mixing of compressible flows in a channel of constant cross-sectional area are derived and are used to investigate the running of an induction-type high-speed wind tunnel. While in practice it is usually difficult to achieve working section Mach numbers greater than about 1.8 to 20 in this type of tunnel, this simple theory gives no obvious reason for this and indicates that higher Mach numbers should be attainable.It is also shown that an increase in efficiency is predicted, particularly at the higher supersonic Mach numbers, if the injected stream enters the mixing section at the same Mach number as that of the working section main stream.
The Flow Past Elliptic-nosed Cylinders and Bodies of Revolution in Supersonic Air Streams
Authors: Holder D. W. , Chinneck A. 
Published: July 2016

SummaryThe flow past families of two-dimensional cylinders and bodies of revolution with elliptic noses at zero incidence has been examined at free stream Mach numbers between 1·42 and 1·82. The observations include schlieren photographs and measurements of the pressure distributions at the surface.The measured pressure distributions and positions of the detached bow waves are found to be in fair agreement with values calculated by a number of methods. The drag coefficients of the slender two-dimensional elliptic noses are considerably higher than those calculated for wedges of the same axis ratio with attached shock waves, but the drags become almost equal when the axis ratio approaches the value for subsonic flow behind the bow wave of the wedge. For most axis ratios the drag coefficients of the elliptic-nosed bodies of revolution are lower than those for cones of the same axis ratio.
The Second Order Terms in Two-Dimensional Tunnel Blockage
Authors: Woods L. C. 
Published: July 2016

SummaryThis paper gives a new calculation of the solid and wake blockage for compressible subsonic flow about a symmetrical two-dimensional aerofoil, midway between symmetrically disposed tunnel walls, which need not be straight. Previous calculations have been based on the theory of sources, and the results obtained have usually involved only first order terms. At high subsonic Mach numbers the second order terms become important; they are given in this paper. The theory is based on an integral equation, which is exact for incompressible flow, and which is more accurate than linear pertubation theory in compressible flow. The effect on blockage of a possible increase in the boundary layer displacement thickness on the tunnel wall, due to the presence of the aerofoil, is investigated, and finally a method of calculating the total blockage from wall pressure measurements is given.
Apparatus for the Remote Recording of Flow Conditions
Authors: Todd K. W. 
Published: July 2016

SummaryAn instrument is described which detects total pressure, total temperature, and direction of flow simultaneously in a stream tube of one-sixteenth inch diameter. The observed directions and pressures are transmitted electrically to a remote station where they appear as pencil traces on a paper record which moves at a rate proportional to the traverse rate of the instrument. The temperature is noted at intervals and added manually to the trace. Integrators are included which permit rapid assessment of mean pressure and direction at the conclusion of a traverse, the control and maintenance of setting of the instrument being semi-automatic. A further development is also noted whereby total pressure and direction in three dimensions can be observed either manually, or remotely, by automatic means.
The Compressible Flow Through Cascade Actuator Discs
Authors: Horlock J. H. 
Published: July 2016

SummaryA theory of the incompressible flow through two- and three-dimensional cascade actuator discs has been developed by several workers over the past ten years, and its accuracy has been confirmed in several experiments. This theory is briefly reviewed, and a parallel theory for subsonic compressible flow through actuator discs is developed. Approximate solutions for several examples are considered, including a compressible shear flow through a two-dimensional cascade, and a compressible flow through an annular cascade of guide vanes.
The Relation between Zero Errors and Bandwidths for Different Types of Rate-of-Turn Meters
Authors: Sutcliffe H. 
Published: July 2016

SummaryIn a conventional rate-of-turn measuring gyroscope the necessity to use a displacement transducer results in an appreciable zero error when a rapid response is required. Other types of instrument, employing alternating forces and force transducers, are also shown to have a relation between error and response time. An assessment is made of these relations and conclusions are reached concerning the relative merits of the different types. The results are given in terms of the estimated rate errors as functions of bandwidth.
Combustion in Liquid-Fuel Rocket Motors
Authors: Spalding D. B. 
Published: July 2016

SummaryThe paper provides a simplified picture of the processes occurring in liquid bi-propellant rocket motors. Droplet vaporisation, chemical reaction, and drag between gas and droplet are considered for a one-dimensional model. Quantitative theoretical results are presented for the variation of droplet size, droplet velocity, gas temperature and gas velocity within the chamber, particular attention being paid to the calculation of L*. The theory is applied to the German V2 rocket motor. Practical conclusions from, and extensions to, the theory are discussed.
The Ground Effect on the Jet Flap in Two Dimensions
Authors: Huggett D. J. 
Published: July 2016

SummaryThe effect of the ground on a jet-flap aerofoil in two-dimensional flow is investigated, with particular reference to the conditions under which the jet flow hits the ground. Experimental results are included for the change of lift and pitching moment for 58·1° and 31·4° jet-deflection angles, with a limited investigation into the downwash changes behind the model with a 58·1° jet-deflection angle. It is concluded that there is a definite limit to the jet coefficient, which may be used at any ground position, if the problems of a sudden change of lift and pitching moment are to be avoided. There remains the unresolved difficulty of the downwash variation at the tail arising from the presence of the ground.A provisional assessment of the performance of a jet-flap aircraft near the ground is made, and shows that for a 58·1° jet-deflection angle there is a definite limit to the minimum flying speed for any given distance of the wing from the ground.The fact that there appears to be a maximum pressure lift coefficient, independent of the jet-deflection angle, which may be obtained at any ground position, is investigated. An attempt is made to provide a theoretical explanation of this on the basis of the critical condition of blockage underneath the aerofoil.
Thermal Stresses in Rectangular Plates
Authors: Przemieniecki J. S. 
Published: July 2016

SummaryThe characteristic functions for beam vibration modes are used to derive an approximate solution for the calculation of thermal stresses in rectangular isotropic flat plates subjected to arbitrary temperature distributions in the plane of the plate and constant temperatures through the plate thickness. The thermal stresses are obtained in the form of generalised Fourier expansions in terms of the characteristic functions, and their derivatives, representing normal modes of vibration of a clamped-clamped beam. Since these functions have recently been tabulated, the practical application of this new method to the thermoelastic stress analysis of plates presents no difficulty.
Supersonic Flow Past Slender Pointed Wings with “Similar” Cross Sections at Zero Lift
Authors: Lord W. T. , Brebner G. G. 
Published: July 2016

SummarySome recent theoretical work on slender pointed wings at zero lift is co-ordinated and extended. The wings considered may have any pointed plan form shape, provided that the trailing edge is straight and unswept. The root section profile and cross-section shapes are arbitrary, provided that, on any one wing, the latter are “descriptively similar” (diamond or parabolic biconvex for instance), though not necessarily geometrically similar. The chief aim of the work is to find wings with simple geometry, low wave drag and pressure distributions which are unlikely to be seriously affected by viscous effects. Wave drag and pressure distributions are calculated by slender-wing theory. General formulae, which are both simple and instructive, are given for the wave drag and the overall pressure distribution, with particular emphasis on the root pressure distribution. Results for a number of wings of special interest are presented and discussed.
The Eftect of Jet Noise on Aircraft Structures
Authors: Clarkson B. L. 
Published: July 2016

SummaryThe present state of knowledge on the problem of fatigue failure due to vibrations excited by jet noise is reviewed. It is concluded that it should currently be possible to make reasonable estimates of the stress levels set up in a structure by jet noise but, in general, the resultant fatigue life of the components cannot be estimated with any confidence.
Flow in a Viscous Trailing Vortex
Authors: Newman B. G. 
Published: July 2016

SummaryThe equations of motion for an isolated laminar viscous vortex at moderate to large Reynolds numbers are linearised, by assuming that both the rotational velocity and the deficit of longitudinal velocity are small compared with that in the free stream. The rotational motion and the longitudinal motion may then be superimposed and solutions are readily obtained for each. If the vortex is generated by a body with profile drag it is predicted that the deficit of longitudinal velocity will be positive, which is in agreement with experimental observation. Further details of the solution and its relation to the flow in real vortices are discussed; and the theory is compared with some measurements in a turbulent vortex.
Asymmetrically Plate-Reinforced Circular Hole in a Uniformly End-Loaded Flat Plate
Authors: Hicks Raymond 
Published: July 2016

SummaryGeneral expressions are obtained for the stress distribution in a flat plate end-loaded by equal principal stresses and containing a circular hole reinforced by an annular plate. The reinforcement is placed on one side of the plate only so that the other side remains flush. It is shown that the effect of an asymmetrically placed reinforcement is to induce, in the plate and rein-forcement, bending stresses which are not negligible compared with the externally applied direct stress. From particular examples it is found that reinforcements having practical dimensions can give rise to stress concentrations in the same order of magnitude as those in a similarly loaded plate containing an unreinforced hole. For practical purposes, data have been obtained which enable the designer to determine quickly the stress distributions associated with reinforcements and plates having a reasonably wide range of dimensions.
The Atmospheric Stress-Corrosion Resistance of some Forged High Strength Aluminium Alloys and an Assessment of the Effects of a Step-Quench into Molten Salt
Authors: Doyle W. M. , Jones R. G. 
Published: July 2016

Since the introduction of aluminium-zinc-magnesium-copper alloys, investigations into the behaviour of these high strength materials, over a wide range of composition, have indicated the significance of corrosion as a factor affecting the cracking of these alloys after prolonged stressing at loads below the ultimate tensile strength of the material.Most of the previous work designed to assess the stress-corrosion resistance of aluminium-zinc-magnesium-copper alloys (D.T.D. 683A*) was carried out on sheet and plate material and the present investigation is concerned with the examination of these materials in the form of large hand-forged slabs, tested in the short transverse direction.
A Theory for Flow with Axial Symmetry in Centrifugal Impellers
Authors: Tonks R. J. , Smith A. G. 
Published: July 2016

SummaryA theory of incompressible flow with axial symmetry through the impeller of a centrifugal compressor is given more fully and more accurately that by previous writers. The theory is applied to compute the flow through two different impellers. For each design the experimental axial velocity distribution at the impeller eye is in good agreement with that computed numerically from the theory. This means that for the impeller assembly—not untypical of modern designs—considered here, theoretical calculation of intake axial velocity should provide a useful guide to designers.
The Bending and Twisting of a Flat Elastic Plate with a Reinforced Circular Hole
Authors: Hicks R. 
Published: July 2016

SummaryThis paper considers the problem of a reinforced circular hole in a bent or twisted flat elastic plate having small deflections. The reinforcement is chosen so that the ratio of its radial width to the diameter of the hole is small; this implies that there is no radial stress variation across sections of the reinforcement. Using the classical theory for bending, expressions are obtained for the boundary conditions at the junction of the reinforcement and plate. The expressions are general in so far as they are also applicable to plates under the action of lateral loading. The following particular problems are considered: —(a) uniform bending about one or two axes, (b) uniform twisting about two axes. For the particular case of uniform bending about one axis, data has been obtained for the stress concentration around holes for plates and reinforcements having a reasonably wide range of practical dimensions.
Experimental Investigation of the Stalled Flow of a Single-Stage Axial Flow Compressor
Authors: Wood M. D. , Horlock J. H. , Armstrong E. K. 
Published: July 2016

SummaryExperimentally it is shown that variation of axial spacing between
neighbouring blade rows can alter the stall characteristics of a compressor
stage. The stall cell patterns of this compressor stage are described in detail
and changes of slope in stage temperature and pressure rise characteristics are
explained in terms of stall propagation. Strain gauge tests on stator blades
are used to indicate the possibility of large dynamic stresses occurring when
the stall cell frequency is equal to the blade natural bending frequency.
Analysis of Stress Concentrations at Reinforced Holes in Infinite Sheets
Authors: Wittrick W. H. 
Published: July 2016

SummaryEquations are derived which enable the stresses around a compactly reinforced hole in an infinite sheet to be computed. The only restrictions placed on the shape of the hole are that it has at least one axis of symmetry and that the region outside it can be conformally mapped on to the region outside the unit circle by a transformation function in the form of a polynomial of any order. This admits a very wide range of holes of practical importance, including circles, ellipses, and squares, triangles and rectangles with rounded corners. Two loading cases are treated; the first corresponds to uniform tensions at infinity in directions parallel and perpendicular to the axis of symmetry of the hole, and the second to uniform shear at infinity in these directions. Superposition of these basic loading cases enables the stresses to be determined for any uniform state of stress at infinity. The equations are in an ideal form for use with a digital computer.
Limitations of the Sonic Area Rule
Authors: Sheppard L. M. 
Published: July 2016

SummaryRecent free flight tests have provided information on the applicability of the sonic area rule to non-lifting configurations. An analysis of results for the sonic wave drag of swept-back, tapered wings has suggested that the sonic area rule is applicable to thin wing and slender body combinations provided that the product of the wing span/length ratio and the cube root of the thickness /chord ratio is less than unity. The wing span/length ratio was found to be a much more useful slenderness parameter than the aspect ratio.When the wing has a round-nosed section, theoretical considerations predict the existence of a so-called leading edge drag force varying with Mach number. One would expect such a wing to have the same sonic drag-rise as the equivalent body with an identical cross-sectional area distribution. Some test results do not confirm this drag-rise equivalence. It appears that the transonic drag-rise of the leading edge force is much greater than that predicted by theory.Tests on one basic wing-body combination, with different body cross-sectional shapes of the same area, suggest that the cross-sectional shape, of a smooth slender body, has no influence on the transonic wave drag of a configuration.
Design Charts for Transient Temperature and Thermal Stress Distributions in Thermally Thick Plates
Authors: Przemieniecki J. S. 
Published: July 2016

SummaryA set of design charts is presented for the calculation of transient temperature and thermal stress distributions in thermally thick plates subjected to aerodynamic heating.The method is particularly useful for determining temperatures and thermal stresses in plates with an arbitrary variation of the heat transfer coefficient and the adiabatic wall temperature of the boundary layer. The present method is based on repetitive applications of the exact analytical solution to a unit triangular variation of the adiabatic wall temperature and a constant heat transfer coefficient. The actual variation of the adiabatic wall temperature is represented as a series of straight lines while the heat transfer coefficient is approximated by a step function. The temperature distribution through the plate is separated into linear and “self-equilibrating” temperature distributions to facilitate thermal stress calculations; these distributions can be obtained directly from the design charts presented in this paper.The general principle of this semi-numerical method is also applied to thermally thin plates subjected to arbitrary heating conditions.