Hydrodynamic Characteristics of a Cambered Hydrofoil With a Jet Flap

1972 ◽  
Vol 39 (2) ◽  
pp. 337-344 ◽  
Author(s):  
Hung-Ta Ho
Keyword(s):  
Pressure Distribution ◽  
Steady Flow ◽  
Polynomial Function ◽  
Cavitation Number ◽  
Numerical Results ◽  
Geometric Parameters ◽  
Hydrodynamic Characteristics ◽  
Pitching Moment ◽  
Cavity Shape ◽  
Linearized Problem

The linearized problem of an infinite steady flow about a thin cambered hydrofoil with a jet flap is solved. The flow is assumed to be inviscid and incompressible and the cavitation number is taken to be zero. It is also assumed that the profile of the foil can be expressed in terms of a polynomial function. Expressions have been obtained for lift, drag, pressure distribution, pitching moment, the jet shape, and the cavity shape. Numerical results are presented for a general “polynomial” foil, and, in particular, Tulin’s low drag foil to show the effects of the geometric parameters of the foil on these hydrodynamic characteristics.

The Linearized Theory of a Supercavitating Hydrofoil With a Jet Flap

1964 ◽  
Vol 86 (4) ◽  
pp. 851-858 ◽  
Author(s):  
Hung-Ta Ho
Keyword(s):  
Theoretical Analysis ◽  
Momentum Flux ◽  
Vortex Sheet ◽  
Cavity Flow ◽  
Cavitation Number ◽  
Pitching Moment ◽  
Cavity Shape ◽  
Small Deflection ◽  
Small Incidence ◽  
Linearized Theory

A theoretical analysis is carried out for the steady cavity flow about thin hydrofoil sections at small incidence α, at the trailing edge of which a thin jet emerges at a small deflection τ. The flow is assumed to be inviscid and incompressible and the cavitation number is taken to be zero. The jet is assumed so thin that it can be considered as a vortex sheet across which the velocity is discontinuous. For the case of a flat plate, expressions have been obtained for lift, drag, pressure distribution, pitching moment, the jet shape, and the cavity shape. Numerical calculations are made for a number of jet momentum-flux coefficients CJ lying between 0.01 and 5.

scholarly journals Influence of Thermodynamic Effect on Blade Load in a Cavitating Inducer

2010 ◽  
Vol 2010 ◽  
pp. 1-7 ◽  
Author(s):  
Kengo Kikuta ◽  
Noriyuki Shimiya ◽  
Tomoyuki Hashimoto ◽  
Mitsuru Shimagaki ◽  
Hideaki Nanri ◽  
...  
Keyword(s):  
Pressure Distribution ◽  
Liquid Nitrogen ◽  
Cavity Length ◽  
Cold Water ◽  
Pressure Rise ◽  
Cavitation Number ◽  
Design Parameters ◽  
Trailing Edge ◽  
Thermodynamic Effect ◽  
Blade Tip

Distribution of the blade load is one of the design parameters for a cavitating inducer. For experimental investigation of the thermodynamic effect on the blade load, we conducted experiments in both cold water and liquid nitrogen. The thermodynamic effect on cavitation notably appears in this cryogenic fluid although it can be disregarded in cold water. In these experiments, the pressure rise along the blade tip was measured. In water, the pressure increased almost linearly from the leading edge to the trailing edge at higher cavitation number. After that, with a decrease of cavitation number, pressure rise occurred only near the trailing edge. On the other hand, in liquid nitrogen, the pressure distribution was similar to that in water at a higher cavitation number, even if the cavitation number as a cavitation parameter decreased. Because the cavitation growth is suppressed by the thermodynamic effect, the distribution of the blade load does not change even at lower cavitation number. By contrast, the pressure distribution in liquid nitrogen has the same tendency as that in water if the cavity length at the blade tip is taken as a cavitation indication. From these results, it was found that the shift of the blade load to the trailing edge depended on the increase of cavity length, and that the distribution of blade load was indicated only by the cavity length independent of the thermodynamic effect.

scholarly journals Experiments and numerical calculation to determine aerodynamic characteristics of flows around 3D wings

2014 ◽  
Vol 36 (2) ◽  
pp. 133-143 ◽  
Author(s):  
Nguyen Hong Son ◽  
Hoang Thi Bich Ngoc ◽  
Dinh Van Phong ◽  
Nguyen Manh Hung
Keyword(s):  
Numerical Calculation ◽  
Wind Tunnel ◽  
Pressure Distribution ◽  
Numerical Method ◽  
Aerodynamic Characteristics ◽  
Numerical Results ◽  
Computational Method ◽  
Wing Surface ◽  
Thickness Profile

The report presents method and results of experiments in wind tunnel to determine aerodynamic characteristics of 3D wings by measuring pressure distribution on the wing surfaces. Simultaneously, a numerical method by using sources and doublets distributed on panel elements of wing surface also is carried out to calculate flows around 3D wings. This computational method allows solving inviscid problems for wings with thickness profile. The experimental and numerical results are compared to each other to verify the built program that permits to extend the range of applications with the variation of wing profiles, wing planforms, and incidence angles.

Numerical Analysis of the Effect of Diffusion and Creep Flow on Cavity Growth

2007 ◽  
Author(s):  
Frederick W. Brust ◽  
Joonyoung Oh
Keyword(s):  
Growth Rate ◽  
Numerical Method ◽  
Cavity Growth ◽  
Volume Growth ◽  
Numerical Results ◽  
Shape Evolution ◽  
Cavity Volume ◽  
Cavity Shape ◽  
Cavity Growth Rate ◽  
Fully Coupled

In this paper, intergranular cavity growth in regimes, where both surface diffusion and deformation enhanced grain boundary diffusion are important, is studied. In order to continuously simulate the cavity shape evolution and cavity growth rate, a fully-coupled numerical method is proposed. Based on the fully-coupled numerical method, a gradual cavity shape change is predicted and this leads to an adverse effect on the cavity growth rates. As the portion of the cavity volume growth due to jacking and viscoplastic deformation in the total cavity volume growth increases, the initially spherical cavity evolves to V-shaped cavity. The numerical results are physically more realistic compared to results in the previous studies. The present numerical results suggest that the cavity shape evolution and cavity growth rate based on an assumed cavity shape, whether spherical or crack-like, cannot be used in this regime due to transitional coupled growth mechanisms.

A Thin Aerofoil of Small Camber in a Non-Uniform Flow

1967 ◽  
Vol 71 (675) ◽  
pp. 214-216
Author(s):  
L. N. Nigam
Keyword(s):  
Pressure Distribution ◽  
Stream Function ◽  
Constant Velocity ◽  
Direct Problem ◽  
Lift Coefficient ◽  
Aerodynamic Characteristics ◽  
Angle Of Incidence ◽  
Pitching Moment ◽  
Image Position ◽  
General Profile

The direct problem of aerodynamics (profile of the aerofoil is given—calculate the aerodynamic characteristics) has been studied for thin aerofoils with small camber. Given the undisturbed stream functionV, ω, α being the constant velocity, vorticity and angle of incidence respectively, the pressure distribution, lift coefficient and pitching moment have been calculated for a general profile.

Numerical Simulation and Analysis for Influence of Wall Effect on Cavity Shape

2013 ◽  
Vol 385-386 ◽  
pp. 400-403
Author(s):  
Fu Yuan Li ◽  
Yu Wen Zhang ◽  
Xi Zhao Du
Keyword(s):  
Numerical Simulation ◽  
Simulation Model ◽  
Empirical Formula ◽  
Diameter Ratio ◽  
Cavitation Number ◽  
Wall Effect ◽  
Water Tunnel ◽  
Cavity Shape ◽  
Model Size ◽  
The Impact

In the experiment of cavitation, the same water tunnel with different model size will get cavity shape that is different from the result of the empirical formula under the same cavitation number. In this article, we studied the impact of wall effect on natural cavity shape and the resistance of cavitator. We get the cavity shape and resistance of cavitator under different diameter ratio. We also get the law how cavity shape and resistance of cavitator change with the diameter ratio. The results provide a reference for experiment in water tunnel and the simulation model.

scholarly journals Optimal Design of Inlet Passage for Waterjet Propulsion System Based on Flow and Geometric Parameters

2019 ◽  
Vol 2019 ◽  
pp. 1-21 ◽  
Author(s):  
Weixuan Jiao ◽  
Li Cheng ◽  
Di Zhang ◽  
Bowen Zhang ◽  
Yeping Su ◽  
...  
Keyword(s):  
Velocity Ratio ◽  
Optimization Method ◽  
Hydraulic Performance ◽  
Numerical Results ◽  
Propulsion System ◽  
Operating Conditions ◽  
Geometric Parameters ◽  
Hydraulic Characteristics ◽  
Design And Optimization ◽  
Ship Speed

As an important overcurrent component in a waterjet propulsion system, the inlet passage is used to connect the propulsion pump and the bottom of the propulsion ship. The anticavitation, vibration, and noise performance of the waterjet propulsion pump are significantly affected by the hydraulic performance of the inlet passage. The hydraulic performance of the inlet passage directly affects the overall performance of the waterjet propulsion system, thus the design and optimization method of the inlet passage is an important part of the hydraulic optimization of the waterjet propulsion system. In this study, the hydraulic characteristics of the inlet passage in the waterjet propulsion system with different flow parameters and geometric parameters were studied by a combination of numerical simulation and experimental verification. The model test was used to verify the hydraulic characteristics of the waterjet propulsion system, and the results show that the numerical results are in good agreement with the test results. The numerical results are reliable. The hydraulic performance of the inlet passage is significantly affected by the inlet velocity ratio. There is a certain correlation between the hydraulic performance of the inlet passage and ship speed, and the hydraulic performance of the inlet passage is limited by ship speed. The geometric parameters of the best optimization case are as follows: the inflow dip angle α is 35°, the length L is 6.38D0, and the upper lip angle is 4°. The optimal operating conditions are the conditions of IVR 0.69–0.87.

Thermoplastic Instability for the Transient Contact Problem of Two Sliding Half-Planes

1986 ◽  
Vol 53 (3) ◽  
pp. 565-572 ◽  
Author(s):  
A. Azarkhin ◽  
J. R. Barber
Keyword(s):  
Steady State ◽  
Pressure Distribution ◽  
Half Plane ◽  
Initial Pressure ◽  
Approximate Solutions ◽  
Steady State Solution ◽  
Fourier Integral ◽  
Numerical Results ◽  
Initial Size ◽  
Transient Contact

We study the time dependent problem of a nonconducting half-plane sliding on the surface of a conductor with heat generation at the interface due to friction. The conducting half-plane is slightly rounded to give a Hertzian initial pressure distribution. Relationships are established for temperature and thermoelastic displacements due to a heat input of cosine type through the surface, and then these are used to obtain the solution in the form of a double Fourier integral. Numerical results show that, if the ratio of the initial size of the area of contact to that in the steady state is less than some critical value, the area of contact and the pressure distribution change smoothly toward the steady state solution. Otherwise the area of contact goes through bifurcation. The bifurcation accelerates the process. Numerical results are compared with previous approximate solutions.

Numerical Simulation of Flow Fluid in Elbow Pipe Based on FLUENT and the Establishment of the Pressure Model

2015 ◽  
Vol 713-715 ◽  
pp. 39-42 ◽  
Author(s):  
Xiao Yang Lu ◽  
Xin Guang Li ◽  
Jin Ming Liu ◽  
Xiao Li Lu ◽  
Hong Liang Zhu ◽  
...  
Keyword(s):  
Pressure Distribution ◽  
Theoretical Basis ◽  
Pipe Wall ◽  
Geometric Parameters ◽  
Analysis Method ◽  
Dimensionless Analysis ◽  
Flow Parameters ◽  
Parameter Variations ◽  
Fluent Simulation ◽  
Simulation Results

According to the FLUENT simulation results of the 90°elbow pipe fluid flow condition, the influence of the pressure distribution about the variation of the flow parameters (v、P0 、ρ) and the geometric parameters (R、d、k=R/d、α、β) is analyzed. By using the dimensionless analysis method, on the basis of the influence of the 32 set of parameter variations on the elbow pipe wall pressure distribution regularity, the pressure qualitative function is established including the geometric parameters and the flow parameters. Through the 155 kinds of the FLUENT simulation results, the fitting software 1stOpt is used to verify the internal pressure model above and fit the undetermined coefficients. The verification shows that the model is of a higher calculation precision and the relative error isn’t exceeding 0.003%. It provides a theoretical basis to check the strength of the bend and design the pipeline with high pressure and speed.

Analysis of Rotating Cavitation in a Finite Pitch Cascade Using a Closed Cavity Model and a Singularity Method

1999 ◽  
Vol 121 (4) ◽  
pp. 834-840 ◽  
Author(s):  
Satoshi Watanabe ◽  
Kotaro Sato ◽  
Yoshinobu Tsujimoto ◽  
Kenjiro Kamijo
Keyword(s):  
Cavity Length ◽  
Gain Factor ◽  
Cavitation Number ◽  
Cavity Model ◽  
Closed Cavity ◽  
Cavity Shape ◽  
Actuator Disk ◽  
Singularity Method ◽  
Eigen Value ◽  
The Stability

A new method is proposed for the stability analysis of cavitating flow. In combination with the singularity method, a closed cavity model is employed allowing the cavity length freely to oscillate. An eigen-value problem is constituted from the boundary and supplementary conditions. This method is applied for the analysis of rotating cavitation in a cascade with a finite pitch and a finite chordlength. Unlike previous semi-actuator disk analyses (Tsujimoto et al., 1993 and Watanabe et al., 1997a), it is not required to input any information about the unsteady cavitation characteristics such as mass flow gain factor and cavitation compliance. Various kinds of instability are predicted. One of them corresponds to the forward rotating cavitation, which is often observed in experiments. The propagation velocity ration of this mode agrees with that of experiments, while the onset range in terms of cavitation number is larger than that of experiments. The second solution corresponds to the backward mode, which is also found in semi-actuator disk analyses and identified in an experiments. Other solutions are found to be associated with higher order cavity shape fluctuations, which have not yet been identified in experiments.

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