A First and Second-Order Theory on a Supercavitating Hydrofoil With a Jet Flap

1974 ◽  
Vol 41 (3) ◽  
pp. 575-580 ◽  
Author(s):  
T. Kida ◽  
Y. Miyai
Keyword(s):  
Asymptotic Expansions ◽  
Deflection Angle ◽  
Order Theory ◽  
Second Order ◽  
Pitching Moment ◽  
Order Problem ◽  
Momentum Coefficient ◽  
Small Deflection ◽  
Small Incidence ◽  
Poincaré Problem

The basic relations for an infinite steady flow around a thin hydrofoil with a jet flap are obtained as the solution of the Riemann-Hilbert-Poincare problem, and the first and second-order problem at small incidence and small deflection angle of the jet is analytically solved by means of the matched asymptotic expansions in the case of the jet-momentum coefficient small. Expressions for lift, drag, pitching-moment, and the cavity shape have been obtained as the asymptotic expansions in powers of the jet-momentum coefficient together with its logarithm. From the comparison of the lift with numerical results of Ho, the analytical method in this paper is seen to be very useful and reasonable.

A Supercavitating Hydrofoil with Mechanical and Jet Flaps Beneath a Free Surface

1978 ◽  
Vol 22 (04) ◽  
pp. 245-256
Author(s):  
Teruhiko Kida ◽  
Takanori Take ◽  
Yoshihiro Miyai
Keyword(s):  
Differential Equation ◽  
Free Surface ◽  
Asymptotic Expansions ◽  
Order Theory ◽  
Hydrodynamic Forces ◽  
Second Order ◽  
Matched Asymptotic Expansions ◽  
Correction Factors ◽  
Integro Differential Equation ◽  
Momentum Coefficient

The flow around a supercavifating hydrofoil equipped with both mechanical and jet flaps, moving beneath a free surface, was analyzed by second-order theory, and the method of matched asymptotic expansions was used to solve the governing integro-differential equation. Hydrodynamic forces which are valid up to the second order of small angles of foil incidence and of jet deflection are determined by asymptotic expansions in terms of the jet-momentum coefficient. Moreover, it is found that Oba's correction factors are not reasonable.

scholarly journals Second-order supercavitating hydrofoil theory

1962 ◽  
Vol 13 (3) ◽  
pp. 321-332 ◽  
Author(s):  
C. F. Chen
Keyword(s):  
Exact Solutions ◽  
Drag Coefficient ◽  
Flat Plate ◽  
Lift Coefficient ◽  
Integral Form ◽  
Order Theory ◽  
Second Order ◽  
Order Problem ◽  
First Order ◽  
Lift And Drag

The second-order problem of Helmholtz flow past lifting hydrofoils and symmetric struts has been formulated and solved. The solution involves elementary operations on the known solutions of the first-order problem. The second-order lift and drag coefficients are given in integral form. Results obtained for a flat plate at incidence and a symmetric wedge agree with the exact solutions up to the second order. In terms of quantitative improvements, the present second-order theory predicts a lift coefficient for a flat plate at 45° incidence with an error of 8%, and a drag coefficient for a symmetric wedge of 50° included angle with an error of 5%; the corresponding angles at which the linear theory would predict force coefficients incurring the same errors are 5° and 15° respectively.

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 Surface wavepackets subject to an abrupt depth change. Part 1. Second-order theory

2021 ◽  
Vol 915 ◽  
Author(s):  
Yan Li ◽  
Yaokun Zheng ◽  
Zhiliang Lin ◽  
Thomas A.A. Adcock ◽  
Ton S. van den Bremer
Keyword(s):  
Order Theory ◽  
Second Order

Abstract

Invariant relative orbits for satellite constellations: A second order theory

2006 ◽  
Vol 181 (1) ◽  
pp. 6-20 ◽  
Author(s):  
F.A. Abd El-Salam ◽  
I.A. El-Tohamy ◽  
M.K. Ahmed ◽  
W.A. Rahoma ◽  
M.A. Rassem
Keyword(s):  
Order Theory ◽  
Second Order ◽  
Satellite Constellations

How Second-Order Is the Regional Level? An Analysis of Tweets in Simultaneous Campaigns

2017 ◽  
Vol 65 (4) ◽  
pp. 1021-1039
Author(s):  
Nicolas Bouteca ◽  
Evelien D’heer ◽  
Steven Lannoo
Keyword(s):  
Order Theory ◽  
Second Order ◽  
Regional Level ◽  
The Political ◽  
Voting Behaviour ◽  
National Parliament ◽  
Political Experience ◽  
Regional Elections

This article puts the second-order theory for regional elections to the test. Not by analysing voting behaviour but with the use of campaign data. The assumption that regional campaigns are overshadowed by national issues was verified by analysing the campaign tweets of Flemish politicians who ran for the regional or national parliament in the simultaneous elections of 2014. No proof was found for a hierarchy of electoral levels but politicians clearly mix up both levels in their tweets when elections coincide. The extent to which candidates mix up governmental levels can be explained by the incumbency past of the candidates, their regionalist ideology, and the political experience of the candidates.

A second-order theory for resonance capture in corotation centers

1999 ◽  
Vol 47 (5) ◽  
pp. 643-652 ◽  
Author(s):  
C. Beauge ◽  
A. Lemaı̂tre ◽  
S. Jancart
Keyword(s):  
Order Theory ◽  
Second Order ◽  
Resonance Capture

Drift Forces on a Floating Body of Simple Geometry Due to Second Order Interactions Between Pairs of Harmonics With Different Frequencies

2009 ◽  
Author(s):  
Joa˜o Pessoa ◽  
Nuno Fonseca ◽  
C. Guedes Soares
Keyword(s):  
Vertical Cylinder ◽  
Vertical Axis ◽  
Second Order ◽  
The Body ◽  
Floating Body ◽  
Order Problem ◽  
Simple Geometry ◽  
The Mean ◽  
Order Quantities ◽  
Drift Forces

The paper presents an investigation of the slowly varying second order drift forces on a floating body of simple geometry. The body is axis-symmetric about the vertical axis, like a vertical cylinder with a rounded bottom and a ratio of diameter to draft of 3.25. The hydrodynamic problem is solved with a second order boundary element method. The second order problem is due to interactions between pairs of incident harmonic waves with different frequencies, therefore the calculations are carried out for several difference frequencies with the mean frequency covering the whole frequency range of interest. Results include the surge drift force and pitch drift moment. The results are presented in several stages in order to assess the influence of different phenomena contributing to the global second order responses. Firstly the body is restrained and secondly it is free to move at the wave frequency. The second order results include the contribution associated with quadratic products of first order quantities, the total second order force, and the contribution associated to the free surface forcing.

Sign in / Sign up

Export Citation Format

Share Document