Interaction Between a Subsonic Air Jet and a Sharp Edge

1984 ◽  
Vol 8 (3) ◽  
pp. 126-132
Author(s):  
N.W.M. Ko
Keyword(s):  
Experimental Investigation ◽  
Mach Number ◽  
Shear Layer ◽  
Coherent Structure ◽  
Wake Flow ◽  
Sharp Edge ◽  
Spectral Measurements ◽  
Acoustic Feedback ◽  
Air Jet ◽  
Set Up

This paper describes an experimental investigation of a jet of Mach number 0.5 which is partially interrupted by an 180° sharp edge. Detailed Schlieren and pressure spectral measurements of the jet with the sharp edge located at different locations inside the jet have indicated the presence of the basic jet coherent structure, the axisymmetrical and azimuthal constituents and the resonances set up by the interaction of the jet flow and sharp edge. The resonances arc due not only to the interaction of the initial shear layer with the acoustic feedback from the basic coherent structure but also with the acoustic feedback from the wake vortices set up in the wake flow behind the sharp edge. For the former, dependence of the level of resonance on location of the sharp edge has also been found.

scholarly journals Correction to: Experimental investigation of blunt cone model at hypersonic Mach number 7.25

2021 ◽  
Vol 43 (7) ◽  
Author(s):  
Saiprakash Mani ◽  
C. Senthilkumar ◽  
G. Kadam Sunil ◽  
Singh Prakash Rampratap ◽  
V. Shanmugam ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Mach Number ◽  
Blunt Cone ◽  
Cone Model

scholarly journals Experimental Investigation of Tandem Blade Cascades With Double-Circular ARC Profiles

1985 ◽  
Author(s):  
Wu Guochuan ◽  
Zhuang Biaonan ◽  
Guo Bingheng
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Mach Number ◽  
Total Pressure ◽  
Incidence Angle ◽  
Axial Direction ◽  
Geometrical Parameters ◽  
Optimal Conditions ◽  
Turning Angle ◽  
Circular Arc

24 double circular are tandem blade cascades of three different chord-ratios were investigated under different displacements in peripheral and axial direction. The inlet Mach number was 0.3. The Reynolds number based on blade chord was 2.7×105. The characteristics of the tandem blade cascades, such as the dependence of turning angle and coefficient of total pressure loss on incidence angle were obtained. The ranges of main geometrical parameters under optimal conditions were recommended.

CFD analysis of free shear layer approximations for a pulsed air jet

2014 ◽  
Vol 43 ◽  
pp. 49-58
Author(s):  
Nawel Khaldi ◽  
Salwa Marzouk ◽  
Hatem Mhiri ◽  
Philippe Bournot
Keyword(s):  
Shear Layer ◽  
Cfd Analysis ◽  
Free Shear Layer ◽  
Air Jet

XXXVIII.—Observations with a Current Meter in Loch Ness

1909 ◽  
Vol 29 ◽  
pp. 619-647 ◽  
Author(s):  
E. M. Wedderburn ◽  
W. Watson
Keyword(s):  
Experimental Investigation ◽  
Fixed Point ◽  
Great Lakes ◽  
Large Lake ◽  
Deep Lakes ◽  
Small Lake ◽  
Stormy Weather ◽  
Set Up ◽  
A Current ◽  
Made In

One of the authors having made an experimental investigation on the currents produced in a trough of water by a blast of air driven along the surface of the water, it was desired to test the correctness of his deductions by actual observations in a large lake. Loch Ness was chosen on account of its length and uniformity of basin, as it was thought that the length and narrowness of the loch would lead to clearly defined currents being set up in the lake. The sequel showed, as in the case of observations on seiches, that it would have been better to confine attention to a smaller lake, for a twofold reason, (1) because in a large lake the difficulties of observations are much greater than in a small lake during stormy weather, and in very deep lakes the difficulties in the way of obtaining a fixed point from which to use the current meter are formidable, and (2) because it would seem from a few observations made in Loch Garry (Ness Basin) that currents are more defined and more regular in small than in great lakes.

First-Order Frequency Effects in Supersonic Panel Flutter of Finite Cylindrical Shells

1973 ◽  
Vol 40 (2) ◽  
pp. 464-470
Author(s):  
M. Holt ◽  
T. M. Lee
Keyword(s):  
Mach Number ◽  
Elastic Shell ◽  
Order Effect ◽  
Aerodynamic Load ◽  
Panel Flutter ◽  
Thin Cylindrical Shell ◽  
First Order ◽  
Flutter Boundary ◽  
Shell Equation ◽  
Set Up

An improved calculation of the supersonic panel flutter characteristics of a thin cylindrical shell of finite length is presented. The aerodynamic load is determined with account taken of first-order terms in vibration frequency, and when this is introduced into the elastic shell equation an integro differential equation results. An equivalent eigenvalue problem is set up by applying Galerkin’s method to this equation. The flutter boundary, for given Mach number and circumferential mode n, corresponds to the shell thickness ratio at which the real part of any one of the eigenvalues first becomes non-negative. It is found that the most severe flutter condition, for given Mach number, occurs for a circumferential mode n = 7. The present calculations exclude second-order frequency terms in the elastic part of the flutter equation, even though they may have a first-order effect. A subsequent calculation referred to here shows that these terms indeed have no significant influence on the first-order analysis.

The structure of weakly compressible grid-generated turbulence

2001 ◽  
Vol 432 ◽  
pp. 219-283 ◽  
Author(s):  
G. BRIASSULIS ◽  
J. H. AGUI ◽  
Y. ANDREOPOULOS
Keyword(s):  
Mach Number ◽  
Large Scale ◽  
Isotropic Turbulence ◽  
Three Dimensional ◽  
High Amplitude ◽  
Time Dependent ◽  
Wide Range ◽  
Dynamical Flow ◽  
Set Up ◽  
Decay Exponent

A decaying compressible nearly homogeneous and nearly isotropic grid-generated turbulent flow has been set up in a large scale shock tube research facility. Experiments have been performed using instrumentation with spatial resolution of the order of 7 to 26 Kolmogorov viscous length scales. A variety of turbulence-generating grids provided a wide range of turbulence scales with bulk flow Mach numbers ranging from 0.3 to 0.6 and turbulent Reynolds numbers up to 700. The decay of Mach number fluctuations was found to follow a power law similar to that describing the decay of incompressible isotropic turbulence. It was also found that the decay coefficient and the decay exponent decrease with increasing Mach number while the virtual origin increases with increasing Mach number. A possible mechanism responsible for these effects appears to be the inherently low growth rate of compressible shear layers emanating from the cylindrical rods of the grid. Measurements of the time-dependent, three dimensional vorticity vectors were attempted for the first time with a 12-wire miniature probe. This also allowed estimates of dilatation, compressible dissipation and dilatational stretching to be obtained. It was found that the fluctuations of these quantities increase with increasing mean Mach number of the flow. The time-dependent signals of enstrophy, vortex stretching/tilting vector and dilatational stretching vector were found to exhibit a rather strong intermittent behaviour which is characterized by high-amplitude bursts with values up to 8 times their r.m.s. within periods of less violent and longer lived events. Several of these bursts are evident in all the signals, suggesting the existence of a dynamical flow phenomenon as a common cause.

scholarly journals Torsion-shear behaviour at the interfaces of rigid interlocking blocks in masonry assemblages: experimental investigation and analytical approaches

2021 ◽  
Vol 54 (3) ◽  
Author(s):  
Claudia Casapulla ◽  
Elham Mousavian ◽  
Luca Argiento ◽  
Carla Ceraldi ◽  
Katalin Bagi
Keyword(s):  
Experimental Investigation ◽  
Ad Hoc ◽  
Pure Shear ◽  
Shear Capacity ◽  
Shear Behaviour ◽  
Main Body ◽  
Shear Failures ◽  
Set Up ◽  
External Forces ◽  
Analytical Approaches

AbstractIncreasing interest has recently been devoted to interlocking blocks/interfaces capable to enhance the sliding resistance of masonry joints to external forces. In this framework, this paper deals with the assessment of the torsion-shear capacity of the contact interface between the lock and the main body of an interlocking block, assumed to have a cohesive behaviour. The interlocking block is a rigid unit which, on its faces, have square cuboidal locks keeping the adjacent/overlapped blocks together and preventing blocks from sliding. Two numerical approaches and a novel ad hoc experimental investigation are proposed to simulate the torsion-shear behaviour by applying eccentrical shear forces to the lock. First, concave, convex and corrected concave formulations provided by the literature for assemblages of rigid blocks with conventional planar joints are extended to model the interlocking block behaviour. Then, according to a second approach based on the discrete element method, the concave-shaped interlocking block is modelled by convex polyhedrons representing the lock and the main body of the block, considered as individual rigid units stacked over each other with a cohesive contact in between. A novel experimental investigation on the limiting pure shear and torsion-shear combinations at the lock interface made of cohesive material is also presented. Two different mortars were chosen to make the specimens, which were casted using 3D printed moulds, and different test configurations were set up to simulate shear and torsion-shear failures. The analytical and numerical results are compared with each other and against the experimental ones, with interesting remarks on the application of the different approaches.

Experimental Investigation of the Flow Through Axisymmetric Expansions

1989 ◽  
Vol 111 (4) ◽  
pp. 464-471 ◽  
Author(s):  
M. Stieglmeier ◽  
C. Tropea ◽  
N. Weiser ◽  
W. Nitsche
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Shear Layer ◽  
Test Facility ◽  
Recirculation Region ◽  
Velocity Measurements ◽  
Forward Scatter ◽  
Separated Shear Layer ◽  
Flow Through ◽  
Diffusion Rates

This study examines the flow field in three axisymmetric expansions having diffuser half-angles of 14, 18, and 90 deg, respectively. Velocity measurements were performed at a Reynolds number of Re = 1.56 × 104 using a single component LDA operated in forward scatter. The test facility was refractive index matched, allowing measurement of the velocities U, V, W, u2, v2, w2, uv and uw upstream of, and throughout the entire recirculation region. The results indicate that the diffuser geometry influences the separated shear layer appreciably over the entire length of the diffuser section. The production of turbulence immediately after separation is much higher in the case of the 14 and 18 deg diffuser compared to the 90 deg expansion, leading to higher diffusion rates in the separated shear layer, and hence earlier reattachment of the shear layer.

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