scholarly journals Experimental studies of supercavitating flow about simple two-dimensional bodies in a jet

1959 ◽  
Vol 5 (3) ◽  
pp. 337-354 ◽  
Author(s):  
Edward Silberman
Keyword(s):  
Linear Theory ◽  
Experimental Studies ◽  
Cavitation Number ◽  
Two Dimensional ◽  
University Of Minnesota ◽  
Flat Plates ◽  
Force Coefficients ◽  
Free Jet ◽  
Fluid Theory ◽  
Good Agreement

A two-dimensional free-jet water tunnel developed at the St Anthony Falls Hydraulic Laboratory of the University of Minnesota is described briefly. Results of experimental measurements on a two-dimensional cup, symmetrical wedges, inclined flat plates, and a circular cylinder in the tunnel are given.Measured force coefficients at zero cavitation number are in good agreement with theory. Shapes of the cavities were computed for one of the wedges and for one of the plates at zero cavitation number; the observed shapes are also in good agreement with the theory.For non-zero cavitation numbers, theoretical results for force coefficients were available for comparison in only two cases. For one of these, the cup, agreement between theory and experiment was good up to a cavitation number of about 0.5. For the other, a symmetrical wedge, experimental results were compared with a linear theory with good agreement for cavitation numbers between about 0.1 and 0.3. In the case of the wedge, measured cavity lengths were somewhat shorter than predicted by the linear theory. All other comparisons with theory at non-zero cavitation number had to be made with the theory as developed for infinite fluid. The experimental force coefficients were less than predicted by infinite-fluid theory, but tended to approach the theoretical values as the cavitation number increased. A similar tendency marked the comparison between the experimental data and data taken by others in closed tunnels.

On Wall Effects in Cavity Flows

1984 ◽  
Vol 28 (01) ◽  
pp. 70-75
Author(s):  
C. C. Hsu
Keyword(s):  
Numerical Results ◽  
Cavity Flows ◽  
Two Dimensional ◽  
Wall Effects ◽  
Free Jet ◽  
Theoretical Predictions ◽  
Experimental Findings ◽  
Good Agreement

Simple wall correction rules for two-dimensional and nearly two-dimensional cavity flows in closed or free jet water tunnels, based on existing linearized analyses, are made. Numerical results calculated from these expressions are compared with existing experimental findings. The present theoretical predictions are, in general, in good agreement with data.

Translational freezing in free jet expansions, with special reference to molecular beam formation

1969 ◽  
Vol 47 (12) ◽  
pp. 2161-2165 ◽  
Author(s):  
Rodney L. LeRoy ◽  
Jacques M. Deckers
Keyword(s):  
Distribution Function ◽  
Transition Region ◽  
Molecular Beam ◽  
Collision Frequency ◽  
Collision Cross Section ◽  
Experimental Studies ◽  
Velocity Distribution Function ◽  
Free Jet ◽  
Beam Formation ◽  
Good Agreement

A theoretical model is described which can be used to calculate the velocity distribution function in the transition region of a free jet expansion. It makes use of a simple mechanism to account for the way in which collisions "perturb" the distribution function which would apply in the absence of collisions. The results are compared with experimental studies of argon beams isolated from free jet sources. If the collision frequency is calculated using a hard sphere collision cross section of (25 ± 5) Å2, good agreement with experimental beam intensity profiles is obtained. In the transition region computed values of the bulk mass velocity, and of the parallel and perpendicular temperatures, are intermediate between the values which would be found if the flow were collision-dominated or free molecular. In particular the perpendicular temperature varies slowly from a dependence on the −4/3 power of the distance from the source, approaching monotonically a −2 power dependence at large distances.

scholarly journals A modification of the CABARET scheme for numerical simulation of multicomponent gaseous flows in two-dimensional domains

2015 ◽  
pp. 436-445
Author(s):  
А.В. Данилин ◽  
А.В. Соловьев ◽  
А.М. Зайцев
Keyword(s):  
Numerical Simulation ◽  
Initial Conditions ◽  
Experimental Studies ◽  
Two Dimensional ◽  
Governing Equations ◽  
Cabaret Scheme ◽  
Gaseous Flows ◽  
Multicomponent Gas ◽  
Good Agreement ◽  
Made In

Предложен явный численный алгоритм для расчета течений смесей идеальных газов в двумерных областях. Приведены физическая модель и уравнения движения смеси в консервативной и характеристической формах. Дискретизация уравнений движения произведена по методике Кабаре. Алгоритм испытан на задачах о прохождении ударной волны в воздухе через неоднородности из легкого и тяжелого газов, начальные условия для которых адаптированы из рассмотренных другими авторами натурных и численных экспериментов. Показано хорошее совпадение расчетов по предложенному алгоритму с результатами этих экспериментов. An explicit numerical algorithm for calculation of two-dimensional motion of multicomponent gas mixtures is proposed. A physical model as well as conservative and characteristic forms of governing equations are given. The discretization of the governing equations is made in accordance with the CABARET (Compact Accurately Boundary Adjusting-REsolution Technique) approach. The proposed algorithm is tested on problems of air shock waves passing through dense and dilute volume inhomogeneities with initial conditions adopted from numerical and experimental studies of other authors. A good agreement between the results of these studies and those obtained by the CABARET approach is shown.

Free Fall Water Entry of a Two-Dimensional Asymmetric Wedge in Oblique Slamming: A Numerical Study

2020 ◽  
Author(s):  
Saeed Hosseinzadeh ◽  
Mohammad Izadi ◽  
Kristjan Tabri
Keyword(s):  
Numerical Study ◽  
Experimental Studies ◽  
Free Fall ◽  
Water Entry ◽  
Vertical Acceleration ◽  
Two Dimensional ◽  
Pile Up ◽  
Real Phenomenon ◽  
Precise Simulation ◽  
Good Agreement

Abstract This paper examines the hydrodynamic problem of a two-dimensional symmetric and asymmetric wedge water entry through freefall motion. The gravity effect on the flow is considered and because of precise simulation close to the real phenomenon, the oblique slamming is analyzed. The defined problem is numerically studied using SIMPLE and HRIC schemes and by implementing an overset mesh approach. In order to evaluate the accuracy of the numerical model, the present results are compared and validated with previous experimental studies and showed good agreement. The results are presented and compared for each symmetry and asymmetry in different deadrise angles, drop heights and heel angles. Based on a comparison of the measured vertical acceleration of the experimental wedge data, it is determined that the proposed numerical method has relatively good accuracy in predicting the slamming phenomenon and wedge response. The influence of viscous regime on water entry simulations is investigated, in according to results, effect of viscosity is negligible. Results show that the heel angle dramatically affects the wedge dynamics, pile-up evolution, and pressure distribution. These results suggest evidence for a complex interaction between geometric parameters on the water entry of rigid wedges, which could finally develop our understanding of planing vessels operating in real sea conditions.

scholarly journals Interaction of Submerged Breakwater by a Solitary Wave Using WC-SPH Method

2014 ◽  
Vol 2014 ◽  
pp. 1-9
Author(s):  
Afshin Mansouri ◽  
Babak Aminnejad
Keyword(s):  
Solitary Wave ◽  
Smoothed Particle Hydrodynamics ◽  
Damping Ratio ◽  
Experimental Studies ◽  
Two Dimensional ◽  
Sph Method ◽  
Submerged Breakwater ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Good Agreement

Interaction of a solitary wave and submerged breakwater is studied in a meshless, Lagrangian approach. For this purpose, a two-dimensional smoothed particle hydrodynamics (SPH) code is developed. Furthermore, an extensive set of simulations is conducted. In the first step, the generated solitary wave is validated. Subsequently, the interaction of solitary wave and submerged breakwater is investigated thoroughly. Results of the interaction of solitary wave and a submerged breakwater are also shown to be in good agreement with published experimental studies. Afterwards, the effects of the inclination and length of breakwater as well as distance between two breakwaters are evaluated on damping ratio of breakwater.

Steady two-dimensional flow through a row of normal flat plates

1990 ◽  
Vol 210 ◽  
pp. 281-302 ◽  
Author(s):  
D. B. Ingham ◽  
T. Tang ◽  
B. R. Morton
Keyword(s):  
Finite Difference ◽  
Stokes Equations ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Corner Singularities ◽  
Flat Plates ◽  
Navier Stokes Equations ◽  
Flow Through ◽  
Good Agreement

A numerical and experimental study is described for the two-dimensional steady flow through a uniform cascade of normal flat plates. The Navier–Stokes equations are written in terms of the stream function and vorticity and are solved using a second-order-accurate finite-difference scheme which is based on a modified procedure to preserve accuracy and iterative convergence at higher Reynolds numbers. The upstream and downstream boundary conditions are discussed and an asymptotic solution is employed both upstream and downstream. A frequently used method for dealing with corner singularities is shown to be inaccurate and a method for overcoming this problem is described. Numerical solutions have been obtained for blockage ratio of 50 % and Reynolds numbers in the range 0 [les ]R[les ] 500 and results for both the lengths of attached eddies and the drag coefficients are presented. The calculations indicate that the eddy length increases linearly withR, at least up toR= 500, and that the multiplicative constant is in very good agreement with the theoretical prediction of Smith (1985a), who considered a related problem. In the case ofR= 0 the Navier–Stokes equations are solved using the finite-difference scheme and a modification of the boundary-element method which treats the corner singularities. The solutions obtained by the two methods are compared and the results are shown to be in good agreement. An experimental investigation has been performed at small and moderate values of the Reynolds numbers and there is excellent agreement with the numerical results both for flow streamlines and eddy lengths.

Experimental Studies on Flexure Pivot Tilting Pad Gas Bearings With Pad Radial Compliance

2007 ◽  
Author(s):  
Kyuho Sim ◽  
Aaron Rimpel ◽  
Daejong Kim
Keyword(s):  
High Speed ◽  
Experimental Studies ◽  
Experimental Results ◽  
Frequency Dependent ◽  
Gas Bearings ◽  
Force Coefficients ◽  
Tilting Pad ◽  
Operation Frequency ◽  
Large Rotor ◽  
Good Agreement

This paper presents experimental studies on imbalance responses of a rotor supported by two flexure pivot tilting pad gas bearings with radial compliance. The radial compliance was aimed to accommodate large rotor centrifugal growth inherent with high speed operation. Frequency-dependent rotordynamic force coefficients calculated from developed software were used to predict critical speeds and onset speed of instability and compared with experimental results. Two results show very good agreement.

scholarly journals Effect of Proximity to Bed on 30° and 45° Inclined Dense Jets: A Numerical Study

2021 ◽  
Author(s):  
Mohammadmehdi Ramezani ◽  
Ozeair Abessi ◽  
Ali Rahmani Firoozjaee
Keyword(s):  
Numerical Study ◽  
Experimental Studies ◽  
Lower Boundary ◽  
Geometrical Properties ◽  
Free Jet ◽  
Rise Height ◽  
Desalination Plants ◽  
Inclined Dense Jets ◽  
Good Agreement ◽  
Return Point

Abstract Employing inclined dense jets is a common way for the disposal of brine effluent from coastal desalination plants. This paper numerically analyzes the mixing and geometrical properties of 30° and 45° inclined dense jets when they discharge close to the bed. For this purpose, two series of numerical simulations were developed. First, the nozzle acts as a free jet when it is placed far enough from the lower boundary. Meanwhile, in the second series, the distance between the nozzle tip and seabed is substantially reduced. Consequently, by comparing these two series, the effect of proximity to bed on the behavior of dense jets is investigated. The governing equations are solved by modifying a solver within the CFD package of OpenFOAM. The numerical results are presented in comparative figures and compared to the previous works. Comparisons indicated that the numerical model predicts the geometrical characteristics of dense jets in good agreement with the past experimental studies. However, the dilution predictions are conservative. It has been observed that proximity to the bed has almost no appreciable effects on the behavior of 45° jets. However, for 30° jets, when the bed proximity parameter ( Y0/LM ) falls below 0.14, normalized values of horizontal and vertical locations of centerline peak and return point dilution are slightly reduced while the terminal rise height remains untouched.

On shear flow past flat plates

1962 ◽  
Vol 14 (3) ◽  
pp. 452-462 ◽  
Author(s):  
Richard M. Mark
Keyword(s):  
Boundary Layer ◽  
Approximate Solution ◽  
Shear Flow ◽  
Asymptotic Solution ◽  
Constant Pressure ◽  
Viscous Incompressible Fluid ◽  
Two Dimensional ◽  
Flat Plates ◽  
Exact Calculations ◽  
Good Agreement

The boundary layer on a semi-infinite flat plate placed in a two-dimensional, unbounded, steady, constant shear flow of a viscous incompressible fluid is examined on the basis of the constant-pressure assumption. An asymptotic solution is obtained first for large vorticity numbers. Then an approximate solution is found for arbitrary vorticity numbers that gives good agreement with exact calculations for the extreme cases of small and large vorticity numbers. The present calculations are limited to the boundary layer on the top side of the plate only.

Comparing selected parameters of a two-dimensional turbulent free jet on the basis of experimental results, digital simulations, and theoretical analyses

2016 ◽  
Vol 1 (20) ◽  
pp. 31-48
Author(s):  
Aldona Skotnicka-Siepsiak
Keyword(s):  
Linear Function ◽  
Analytical Methods ◽  
Relative Length ◽  
Wall Layer ◽  
Turbulence Level ◽  
Two Dimensional ◽  
Free Jet ◽  
Theoretical Assumptions ◽  
Digital Simulations ◽  
Theoretical Analyses

The presented experimental and digital examinations of a two-dimensional turbulent free jet are a first phase of in the study of the Coandă effect and its hysteresis. Additionally, basing on theoretical analyses, selected results for a turbulent jest have been also mentioned, considering theoretical assumptions for the wall layer. As the result, on the basis of experimental, digital, and analytical methods, a review of characteristic jet properties has been prepared, which includes a jet spreading ratio, its cross and longitudinal sections, and turbulence level. The jet spreading radio has been expressed as a non-linear function of the x : b relative length.

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