Tomo-PIV Measurements of Flow Around A Slender Body at High Angles of Attack

2015 ◽  
pp. 131-136
Author(s):  
S. Alzahrani ◽  
S. Hafez ◽  
K. A. Juhany ◽  
I. M. AlQadi
Keyword(s):  
Slender Body ◽  
Piv Measurements ◽  
High 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 investigations of the asymmetric vortex formation over a slender body of revolution at high angles of attack

2020 ◽  
Vol 34 (14n16) ◽  
pp. 2040089
Author(s):  
Yiding Zhu
Keyword(s):  
Vortex Formation ◽  
The Body ◽  
Slender Body ◽  
Experimental Investigations ◽  
Initial Growth ◽  
Body Of Revolution ◽  
Momentum Exchange ◽  
Time Resolved ◽  
High Angles Of Attack ◽  
Slender Body Of Revolution

This paper describes an experimental investigation of the initial growth of flow asymmetries over a slender body of revolution at high angles of attack with natural and disturbed noses. Time-resolved particle image velocimetry (PIV) is used to investigate the flow field around the body. Flow visualization clearly shows the formation of the asymmetric vortices. Instantaneous PIV shows that the amplified asymmetric disturbances lead to Kelvin–Helmholtz instability appearing first on one side, which increases the momentum exchange crossing the layer. As a result, the separation region shrinks which creates the initial vortex asymmetry.

scholarly journals Investigation of Flow Around a Slender Body at High Angles of Attack

2019 ◽  
Vol 30 (1) ◽  
pp. 51-61
Author(s):  
Ibraheem AlQadi Ibraheem AlQadi
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
The Body ◽  
Slender Body ◽  
Frequency Mode ◽  
Dynamic Mode ◽  
High Frequency Mode ◽  
Wide Range ◽  
Low Frequency Mode ◽  
High Angles Of Attack

A numerical investigation of flow around a slender body at high angles of attack is presented. Large eddy simulation of the flow around an ogive-cylinder body at high angles of attack is carried out. Asymmetric vortex flow was observed at angles of attack of α = 55◦ and 65◦ . The results showed that the phenomenon is present in the absence of artificial geometrical or flow perturbation. Contrary to the accepted notion that flow asymmetry is due to a convective instability, the development of vortex asymmetry in the absence of perturbations indicates the existence of absolute instability. An investigation of the unsteady flow field was carried out using dynamic mode decomposition. The analysis identified two distinct unsteady modes; high-frequency mode and low-frequency mode. At angle of attack 45◦ the high-frequency mode is dominant in the frontal part of the body and the low-frequency mode is dominant at the rear part. At α = 55◦ , the highfrequency mode is dominant downstream of vortex breakdown. At α = 65◦ , the spectrum shows a wide range of modes. Reconstruction of the dynamical modes shows that the low-frequency mode is associated with the unsteady wake and the high-frequency mode is associated with unsteady shear layer.

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 Simulation of flow around a slender body at high angles of attack

2017 ◽  
Vol 104 ◽  
pp. 02018
Author(s):  
Osama Obeid ◽  
Ibraheem Alqadi
Keyword(s):  
Slender Body ◽  
High Angles Of Attack
Sign in / Sign up

Export Citation Format

Share Document