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.

scholarly journals Effect of a Circular Ring on the Side Force of a Cone-Cylinder Body

2020 ◽  
Author(s):  
Shashank Gaurav ◽  
Sudip Das ◽  
Priyank Kumar
Keyword(s):  
Angle Of Attack ◽  
Circular Ring ◽  
Diameter Ratio ◽  
The Body ◽  
Base Diameter ◽  
Initial Portion ◽  
Side Force ◽  
Nose Shape ◽  
Almost All ◽  
Local Diameter

This paper aims to investigate the side force on a cone-cylinder geometry at different angles of attack (α) by adopting experiments and computations. The cone-cylinder configuration had a length to diameter ratio (L/D) of 10, and a base diameter (D) of 25 mm. The nose shape had a fineness ratio of approximately 3. Results indicated that the side force increases with the increasing of the angle of attack. A circular ring was used to reduce the side force at different angles of attack. Using a smaller height ring (2% of local diameter) in the initial portion of the body did not reduce the side force significantly at lower angles of attack. However, a ring with larger height (5% of local diameter) placed at 2.5 times the diameter of the body from the tip reduced the side force at almost all the angles of attack.

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.

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°.

Effect of ring size on the side force over ogive-cylinder body at subsonic speed

2016 ◽  
Vol 120 (1231) ◽  
pp. 1487-1506 ◽  
Author(s):  
P. Kumar ◽  
J.K. Prasad
Keyword(s):  
Rectangular Cross Section ◽  
Substantial Reduction ◽  
Circular Ring ◽  
The Body ◽  
Leeward Side ◽  
Axial Distance ◽  
Base Diameter ◽  
Freestream Velocity ◽  
Side Force ◽  
Lift And Drag

ABSTRACTExperiments and computations have been made to obtain the details of the flow field over a slender body at high angles of attack at a freestream velocity of 17 m/s corresponding to a Reynolds number of 2.9×104based on the base diameter. Experiments indicated that the existence of side force at higher angles of attack is mainly due to the presence of asymmetric vortices in the leeward side. A rectangular cross-section circular ring placed at an axial distance of 3.5 times the base diameter reduced the side force at all the angles of attack. Investigations were made to obtain the effect of the height of the ring at an angle-of-attack of 50° where the side force experienced is relatively large. A ring placed at a distance of 3.5 times the base diameter alters the initial vortices and hence helps in substantial reduction of the side force. Studies with rings of different heights indicate that a ring having a height of 3% of the local diameter reduced the side force at almost all the angles of attack for the present flow conditions and provided the least disturbance to the lift and drag of the body.

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.

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.

Slender-body theory for slow viscous flow

1976 ◽  
Vol 75 (4) ◽  
pp. 705-714 ◽  
Author(s):  
Joseph B. Keller ◽  
Sol I. Rubinow
Keyword(s):  
Integral Equation ◽  
Incompressible Fluid ◽  
Viscous Incompressible Fluid ◽  
Unit Length ◽  
The Body ◽  
Slender Body ◽  
Slow Flow ◽  
Slender Body Theory ◽  
Slow Viscous Flow ◽  
Body Theory

Slow flow of a viscous incompressible fluid past a slender body of circular crosssection is treated by the method of matched asymptotic expansions. The main result is an integral equation for the force per unit length exerted on the body by the fluid. The novelty is that the body is permitted to twist and dilate in addition to undergoing the translating, bending and stretching, which have been considered by others. The method of derivation is relatively simple, and the resulting integral equation does not involve the limiting processes which occur in the previous work.

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).

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