이수건 교수

The effect of the porous leading edge of an airfoil on the blade-vortex interaction noise, which dominates the far-field acoustic spectrum of the helicopter, is investigated. The thin-layer Navier-Stokes equations are solved with a high-order upwind-biased scheme and a multizonal grid system. The Baldwin-Lomax turbulence model is modified for considering transpiration on the surface. The amplitudes of the propagating acoustic wave in the near field are calculated directly from the computation. T

An experimental and computational study was carried out to investigate the parallel head-on blade-vortex interaction (BVI) and its noise generation mechanism. A shock tube, with an enlarged test section, was used to generate a compressible starting vortex which interacted with a target airfoil. The dual-pulsed holographic interferometry (DPHI) technique and airfoil surface pressure measurements were employed to obtain quantitative flow data during the BVI. A thin-layer Navier-Stokes code (BV12D)

This paper describes a hovering rotor blade design through the suitable combination of flow analysis and optimization technique. It includes a parametric study concerned with the influence of design variables and different design conditions such as objective functions and constraints on the rotor performance. Navier–Stokes analysis is employed to compute the hovering rotor performance in subsonic and transonic operating conditions. Response surface method based on D-optimal 3-level factorial des

Abstract A numerical study on impulsive noise generation produced by complex flows discharging from a muzzle is achieved and the basic structures generating impulsive noise are analyzed. Complex flow features by a muzzle flow and noise generation mechanisms by several sources of noise are discussed from numerical simulations. Two‐dimensional axisymmetric Euler equations are used for governing equations. High‐order dispersion relation preserving finite difference method and an optimized four‐leve

A stochastic numerical analysis of a multirotor was performed considering the rotational speed fluctuation to investigate the acoustic characteristics. To validate the analysis, the noise was measured in an anechoic chamber at different azimuth angles (from 0° to 45°) and polar angles (from 0° to 67.5°) in revolutions per minute (RPM) assuming a multirotor hovering maneuver. Frequency and amplitude modulation characteristics due to RPM fluctuations were observed despite the considered hovering c