scholarly journals Experimental and Numerical Investigations of Slender Body Side Force with Asymmetric Protuberances

2019 ◽  
Vol 56 (5) ◽  
pp. 1346-1357 ◽  
Author(s):  
K. Kawauchi ◽  
T. Harada ◽  
K. Kitamura ◽  
S. Nonaka
Keyword(s):  
Slender Body ◽  
Side Force ◽  
Numerical Investigations ◽  
Body Side

Strakes Effects on Asymmetric Flow Over a Blunt-Nosed Slender Body at a High Angle of Attack

2018 ◽  
Vol 141 (6) ◽  
Author(s):  
Qihang Yuan ◽  
Yankui Wang ◽  
Zhongyang Qi
Keyword(s):  
Angle Of Attack ◽  
Slender Body ◽  
Axial Position ◽  
High Angle ◽  
Asymmetric Flow ◽  
High Angle Of Attack ◽  
Side Force ◽  
Asymmetric Vortices ◽  
High Angles Of Attack ◽  
Blunt Nose

In general speaking, the missiles execute flight at high angles of attack in order to enhance their maneuverability. However, the inevitable side-force, which is caused by the asymmetric flow over these kinds of traditional slender body configurations with blunt nose at a high attack angle, induces the yawing or rolling deviation and the missiles will lose their predicted trajectory consequently. This study examines and diminishes the side-force induced by the inevitable asymmetric flow around this traditional slender body configuration with blunt nose at a high angle of attack (AoA = 50 deg). On one hand, the flow over a fixed blunt-nosed slender body model with strakes mounted at an axial position of x/D = 1.6–2.7 is investigated experimentally at α = 50 deg (D is the diameter of the model). On the other hand, the wingspan of the strakes is varied to investigate its effect on the leeward flow over the model. The Reynolds number is set at ReD = 1.54 × 105 based on D and incoming upstream velocity. The results verify that the formation of asymmetric vortices is hindered by the existence of strakes, and the strake-induced vortices develop symmetrically and contribute to the reduction in side-force of the model. In addition, the increase in strake wingspan reduces asymmetric characteristics of the vortex around the model and causes a significant decrease in side-force in each section measured. The strake with the 0.1D wingspan can reduce the sectional side-force to 25% of that in the condition without strakes.

Side Forces on a Ship’s Hull

1988 ◽  
Vol 32 (03) ◽  
pp. 203-207
Author(s):  
W. S. Hunter ◽  
P. N. Joubert
Keyword(s):  
Froude Number ◽  
Asymptotic Expansions ◽  
Experimental Results ◽  
Slender Body ◽  
Flat Plates ◽  
Slender Body Theory ◽  
Towing Tank ◽  
Side Force ◽  
Low Froude Number ◽  
Body Theory

Side forces on a ship traveling at small yaw angles are predicted using slender-body theory. The approach uses the method of matched asymptotic expansions, with a cascade of flat plates as a model for the submarine portion of the ship's hull. Resulting predictions of side force coefficients are then compared with experimentally measured values derived from towing tank tests of a typical (tanker) hull. Correlation between theoretical and experimental results was very good for yaw angles less than 8 deg at low Froude number (Fn = 0.134).

EXPERIMENTAL INVESTIGATION OF SLENDERNESS EFFECT ON SIDE FORCE OF SLENDER BODY

2010 ◽  
Vol 24 (13) ◽  
pp. 1413-1416 ◽  
Author(s):  
TZONG-SHYNG LEU ◽  
JENG-REN CHANG ◽  
CHUN-LIN KUO
Keyword(s):  
Body Surface ◽  
The Body ◽  
Slender Body ◽  
Force Distribution ◽  
Wall Region ◽  
Side Force ◽  
Major Mechanism ◽  
Body Experiences ◽  
Formation And Evolution ◽  
Near Wall

This study investigates side force of a slender body with slenderness from 4.4 to 8.0. The experimental results show that flow over a slender body experiences a significant side force at angle-of-attack (AOA) higher than 30°. The side force reaches its maximum at AOA ≈ 50°. The present study demonstrates that slenderness (L/D) produces obvious influence on sectional side force distribution at high AOA. To understand the mechanism, evolution of near-wall vortex structure is investigated via hot wire and surface pressure measurements. It was found that one strong vortex is situated close to body surface and the other weak vortex away from the body, inducing a significant side force. Because the weak vortex lifts off early, a new vortex forms in near-wall region. Formation and evolution of the new vortex is the major mechanism that causes local sectional side force distribution exhibiting a wavy form with an alternating sign along the body. Therefore, overall side force does not necessarily increase with increasing slenderness. Reducing overall side force by canceling the alternating vortex-induced forces over the body surface is found if the slenderness L/D > 6.8 at AOA > 40°.

The influence of Chine nose shapes on a slender body flight vehicle at high angles of attack

2011 ◽  
Vol 226 (2) ◽  
pp. 182-196 ◽  
Author(s):  
S Lim ◽  
S D Kim ◽  
D J Song
Keyword(s):  
Three Dimensional ◽  
Flow Characteristics ◽  
Cross Flow ◽  
Slender Body ◽  
Flight Vehicle ◽  
Side Force ◽  
Turbulent Transition ◽  
Flow Vortex ◽  
High Angles Of Attack ◽  
Laminar Turbulent Transition

The flow characteristics of asymmetric vortices and the side force of a slender body flight vehicle with chine nose at high angles of attack have been studied using a three-dimensional upwind Navier–Stokes method with the k– ω turbulence model and a simple laminar–turbulent transition model. Asymmetrically changing turbulent viscosities that arise from asymmetric laminar–turbulent transition conditions cause asymmetric cross-flow vortex structures and side forces at higher angles of attack. However, certain type of edges may cause fixed flow separations on these edges. In this study, the chine nose shape with chine edge on its both sides is considered for the method to reduce side force. The asymmetric flow control capacity of chine nose shapes at high angles of attack is studied.

scholarly journals Rolling Moment of Slender Body at High Incidence for Air to Air Missile Rocket Applications

2020 ◽  
Vol 70 (1) ◽  
pp. 18-22
Author(s):  
Priyank Kumar
Keyword(s):  
Diameter Ratio ◽  
The Body ◽  
Slender Body ◽  
Control Technique ◽  
Angle Of Incidence ◽  
Rolling Moment ◽  
Side Force ◽  
High Incidence ◽  
Nose Shape ◽  
Length To Diameter Ratio

Measurements of moments were carried out on a slender body having a pointed forebody at lower velocities. The slender body had an ogive nose shape and an overall length to diameter ratio of 16. The angle of incidence was varied from low to moderate angles of attack in the pitch plane. The main objective of the present investigation was to measure the rolling moments on the slender body with and without the control technique. The side force was reduced using a rectangular cross-sectioned ringplaced suitably on the body, however, the slender body was found to experience rolling moments which may be catastrophic.

scholarly journals Side force control on slender body by self-excited oscillation flag

2016 ◽  
Vol 6 (5) ◽  
pp. 230-232 ◽  
Author(s):  
Jian Zhai ◽  
Weiwei Zhang ◽  
Chuanqiang Gao ◽  
Yanhua Zhang ◽  
Zhengyin Ye ◽  
...  
Keyword(s):  
Force Control ◽  
Slender Body ◽  
Side Force ◽  
Excited Oscillation

Side force over slender body with rings at different location at subsonic speed

2016 ◽  
Vol 231 (8) ◽  
pp. 1478-1491 ◽  
Author(s):  
P Kumar ◽  
JK Prasad
Keyword(s):  
The Body ◽  
Slender Body ◽  
Flow Conditions ◽  
Base Diameter ◽  
Initial Portion ◽  
Side Force ◽  
Model Base ◽  
Axial Location ◽  
Subsonic Speed ◽  
Asymmetric Vortices

Investigations have been made adopting experiments and computations on an ogive-nosed slender body at different angles of attack and Reynolds number of 29,000 based on the model base diameter diameter. The results indicated an increase in the side force at large angles of attack, which is mainly due to the presence of asymmetric vortices in the leeward of the body. The inclusion of a rectangular cross-sectioned ring in the initial portion of the body reduced the side force at higher angles of attack. However, significant side force was experienced at lower angles of attack (30° < α < 40°). Use of a ring of 3% height was found to be suitable for reducing the side force at a higher angle of attack. From the results obtained it was observed that a ring if placed at a different axial location alters the flow field and changes the side force at higher angles of attack. Further studies indicated that placing of rings pair at an axial location of 3.5 and 4.5 times the base diameter reduced the side force to a very low value at all the angles of attack for the present shape of body and flow conditions.

Axial Evolution of Asymmetric Vortical Flow Around Slender Body of Revolution at High Incidence

2010 ◽  
Author(s):  
Xiaorong Guan ◽  
Song Fu ◽  
Cheng Xu
Keyword(s):  
Mach Number ◽  
The Body ◽  
Slender Body ◽  
Vortical Flow ◽  
Computational Results ◽  
Body Of Revolution ◽  
Evolution Law ◽  
Side Force ◽  
High Incidence ◽  
Slender Body Of Revolution

For studying the axial evolution of the flow around slender body of revolution at high incidence under different conditions, numerical simulations are performed. Based on the computational results, several conclusions and deductions are obtained. When the flow is asymmetric and whether the asymmetry is remarkable or not, downstream axially it always presents itself in the structure of leeside vortices forming, rising and shedding alternately from opposite sides of the body and induces the sectional side force of waving sinusoidally. Based on the idea of vortex dividing, a forming mode of shed and new leeside vortices is put forward, which is composed of two idiographic manners. The axial evolutions on the forming manner can be reduced to three idiographic laws. The global asymmetry degree of the flow lies on both the axial evolution law on the forming manner and the intensity of leeside vortex. The influences of incidence, freestream Mach number and nose-perturbation location on the axial evolution of the asymmetric vortical flow are achieved as well.

Men’s Hunger, Food Consumption, and Preferences for Female Body Types

2014 ◽  
Vol 45 (6) ◽  
pp. 495-497 ◽  
Author(s):  
Nicolas Guéguen
Keyword(s):  
Food Consumption ◽  
Female Body ◽  
The Body ◽  
Slender Body ◽  
Mediation Effect ◽  
Point Scale ◽  
Body Type ◽  
Experimental Conditions

Nelson and Morrison (2005 , study 3) reported that men who feel hungry preferred heavier women. The present study replicates these results by using real photographs of women and examines the mediation effect of hunger scores. Men were solicited while entering or leaving a restaurant and asked to report their hunger on a 10-point scale. Afterwards, they were presented with three photographs of a woman in a bikini: One with a slim body type, one with a slender body type, and one with a slightly chubby body. The participants were asked to indicate their preference. Results showed that the participants entering the restaurant preferred the chubby body type more while satiated men preferred the thinner or slender body types. It was also found that the relation between experimental conditions and the choices of the body type was mediated by men’s hunger scores.

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