Aircraft Spoilers Aerodynamics Mechanism of Braking During Landing and the Associated Radiated Tonal Noise
Journal Title: Libyan Journal of Engineering Science and Technology - Year 2024, Vol 4, Issue 1
Abstract
Spoilers are panels mounted on the suction surface of aircrafts wings. Their main function is to slow the aircraft down during landing. In this article, numerical simulations of the flow around a wing airfoil with spoiler have been carried out using the software Ansys Fluent. It is of supercritical airfoils category, NASA SC (2) – 0610. The main objective of this research is to calculate the drag, lift and pressure coefficients at different spoiler angles of deflections in order to explain the mechanism of the aircraft braking and lift spoiling when the spoiler is deflected during landing and to calculate the corresponding radiated tonal noise. The results show that the pressure increases in front of the spoiler while behind the spoiler, it decreases significantly because of flow separation. The pressure differences between front and back spoiler surfaces leads to an increase in the form drag and thus creating the braking on the aircraft. The other effect of the spoiler is to spoil the lift. This is a result of the increased pressure on the upper surface in front of the spoiler which causes a reduction in the lift coefficient and pushes the aircraft down, the lift coefficient is found negative and equal to -0.4313 for a spoiler angle of deflection 70°. The dominant frequency of the vortex shedding has been calculated and found equal to 29 Hz. This frequency is expected to appear and to be dominant in the wing vibrations and noise signals. The aerodynamics noise generated by the deflection of the spoiler at an angle of 70° is finally computed using the Ffowcs-Williams and Hawking (FWH) aeroacoustics analogy. It has been found that the radiated noise is a tonal noise in its nature because its principle source is the vortex shedding and its dominant frequency equal to the frequency of vortex shedding, around 29 Hz. The Sound Pressure Level (SPL) main pic arrives to 120 dB at a frequency of almost 29 Hz for a receiver located at a distance of 2 m above the airfoil trailing edge.
Authors and Affiliations
Rabea Matouk¹, Ayoub Abdulqader² and Huda Mohammed5
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