Effect of Angle of Attack and Mach Number on Slender-Wing Unsteady Aerodynamics

1978 ◽  
Vol 15 (6) ◽  
pp. 358-365 ◽  
Author(s):  
Lars E. Ericsson ◽  
J. Peter Reding
Keyword(s):  
Mach Number ◽  
Angle Of Attack ◽  
Unsteady Aerodynamics ◽  
Slender Wing

Wake measurements of oscillating supercritical airfoil in compressible flow

2019 ◽  
Vol 43 (1) ◽  
pp. 112-121
Author(s):  
Behnaz Beheshti Boroumand ◽  
Mahmoud Mani
Keyword(s):  
Mach Number ◽  
Angle Of Attack ◽  
Time History ◽  
Mean Value ◽  
Hot Wire ◽  
Dynamic Tests ◽  
Flow Parameters ◽  
Free Stream Mach Number ◽  
Static And Dynamic Tests ◽  
Wake Characteristics

Boundary layer and wake behaviors are strongly affected by airfoil motion. Moreover, parameters like body oscillation frequency, oscillation type, Mach number, and angle of attack play main roles in wake characteristics. In this research, both static and dynamic tests were carried out in a tri-sonic wind tunnel to study wake profiles experimentally by hot wire anemometry. All data were recorded at a free stream Mach number of 0.4. Quarter-length and half-length of chord were also considered as downstream distances from the trailing edge in pitching motions of mean angle of attack of −0.4°. Frequencies of 3 Hz and 6 Hz with amplitude of 3° were chosen as oscillation parameters. Voltages at hot wire outputs were measured and analyzed qualitatively and statistically with root-mean-square, correlation, mean value distribution, time history, and frequency. Flow parameters were obtained by computational studies under similar experimental test conditions. The wake characteristics obtained from numerical and experimental methods were compared.

scholarly journals AERODYNAMIC MODELING OF OSCILLATING WING IN HYPERSONIC FLOW: A NUMERICAL STUDY

2016 ◽  
Vol 42 ◽  
pp. 1660177
Author(s):  
JIAN ZHU ◽  
YING-YU HOU ◽  
CHEN JI ◽  
ZI-QIANG LIU
Keyword(s):  
Mach Number ◽  
Hypersonic Flow ◽  
Numerical Study ◽  
Unsteady Aerodynamics ◽  
Order Theory ◽  
Second Order ◽  
Double Wedge ◽  
Piston Theory ◽  
Impact Theory ◽  
Cfd Method

Various approximations to unsteady aerodynamics are examined for the unsteady aerodynamic force of a pitching thin double wedge airfoil in hypersonic flow. Results of piston theory, Van Dyke’s second-order theory, Newtonian impact theory, and CFD method are compared in the same motion and Mach number effects. The results indicate that, for this thin double wedge airfoil, Newtonian impact theory is not suitable for these Mach number, while piston theory and Van Dyke’s second-order theory are in good agreement with CFD method for Ma<7.

Numerical Simulation of Unsteady Aerodynamic Loads over an Aircraft

2014 ◽  
Vol 908 ◽  
pp. 264-268
Author(s):  
Xiao Jun Xiang ◽  
Yu Qian
Keyword(s):  
Mach Number ◽  
Euler Equations ◽  
Unsteady Aerodynamics ◽  
Periodic Motions ◽  
Aerodynamic Loads ◽  
Unsteady Aerodynamic ◽  
Sinusoidal Motion ◽  
A Cell ◽  
Rigid Body Motions ◽  
Volume Method

The unsteady aerodynamic loads are the basic of the aeroelastic. This paper focuses on the computation of the unsteady aerodynamic loads for forced periodic motions under different Mach numbers. The flow is modeled using the Euler equations and an unsteady time-domain solver is used for the computation of aerodynamic loads for forced periodic motions. The Euler equations are discretized on curvilinear multi-block body conforming girds using a cell-centred finite volume method. The implicit dual-time method proposed by Jameson is used for time-accurate calculations. Rigid body motions were treated by moving the mesh rigidly in response to the applied sinusoidal motion. For an aircraft model, a validation of the unsteady aerodynamics loads is first considered. Furthermore, a study for understanding the influence of different Mach number was conducted. A reverse of the trend of hysteretic loops can be observed with the increasing of the Mach number.

Effect of airfoil leading edge waviness on flow structures and noise

2016 ◽  
Vol 26 (6) ◽  
pp. 1821-1842 ◽  
Author(s):  
Man Zhang ◽  
Abdelkader Frendi
Keyword(s):  
Mach Number ◽  
Angle Of Attack ◽  
Leading Edge ◽  
Space Time ◽  
Flow Structures ◽  
Mean Flow ◽  
Content Type ◽  
Acoustic Signature ◽  
Depth Analysis ◽  
Time Correlations

Purpose – The tubercles at the leading edge of Humpback Whale flippers have been shown to increase aerodynamic efficiency. The purpose of this paper is to compute the flow structures and noise signature of a NACA0012 airfoil with and without leading edge waviness, and located in the wake of a cylinder using the hybrid RANS-LES method. Design/methodology/approach – The mean flow Mach number is 0.2 and the angle of attack used is 2°. After benchmarking the method using existing experimental results, unsteady computations were then carried-out on both airfoil geometries and for a 2° angle of attack. Findings – Results from these computations confirmed the aerodynamic benefits of the leading edge waviness. Moreover, the wavy leading edge airfoil was found to be at least 4 dB quieter than its non-wavy counterpart. In-depth analysis of the computational results revealed that the wavy leading edge airfoil breaks up the large coherent structures which are then convected at higher speeds down the trough region of the waviness in agreement with previous experimental observations. This result is supported by both the two-point and space-time correlations of the wall pressure. Research limitations/implications – The limitations of the current findings reside in the fact that both the Reynolds number and the flow Mach number are low, therefore not applicable to aircrafts. In order to extend the study to practical aircrafts one needs huge grids and large computational resources. Practical implications – The results obtained here could have a huge implications on the design of future aircrafts and spacecrafts. More specifically, the biggest benefit from such redesign is the reduction of acoustic signature as well as increased efficiency in fuel consumption. Social implications – Reducing acoustic signature from aircrafts has been a major research thrust for NASA and Federal Aviation Administration. The social impact of such reduction would be improved quality of life in airport communities. For military aircrafts, this could results in reduced detectability and hence saving lives. Originality/value – Humpback Whales have been studied by various researchers to understand the effects of leading edge “tubercles” on flow structures. What is new in this study is the numerical confirmation of the effects of the tubercles on the flow structures and the resulting noise radiations. It is shown through the use of two-point correlations and space-time correlations that the flow structures in the trough area are indeed vortex tubes.

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