Presentation at 2012 Asia-Pacific International Symposium on Aerospace Technology, APISAT 2012
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APISAT 2012
Vortex Dissipation Due to Airfoil-Vortex Interaction
Keitaroh OHSHIO (Tokyo Metropolitan University)
Masahiko SUGIURA (Aviation Program Group, JAXA)
Yasutada TANABE (Aviation Program Group, JAXA)
Hideaki SUGAWARA (Ryoyu Systems, Co., Ltd.)
Masahiro KANAZAKI (Tokyo Metropolitan University)
0148 Nov. 14, 2012 Ramada Plaza Hotel, Jeju, Korea
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Toward An Improvement of The Hybrid Method of
Prescribed Wake Model/CFD
Presentation Outline
Background
Change of vortex trajectory and circulation
Sound pressure fluctuation
Concluding remarks
Objective
2
Calculation results
Methodologies
3
Engine noise
Transmission noise
HSI noise
BVI noise
The simulation of BVI has to be
Tip vortex
BVI
Tail rotor noise
BVI noise has to be reduced for
next generation helicopters. Dominant parameters
・ Vertical distance between
blade and vortex center
(=miss-distance)
・ Vortex circulation high-accurate
low-cost
Development of BVI Noise Prediction Method
CFD:Computational Fluid Dynamics
4
CFD
Prescribed wake model
Hybrid method
CFD
Prescribed wake model
(Estimation of the pressure distribution on blades)
(Estimation of the induced velocity)
V :Freestream velocity
αTPP :Rotor angle of attack
Ω :Rotor rotational speed
R :Rotor radius
Ψv :Vortex age
Ψb :Blade azimuth at vortex release
xv = RcosΨv + μx(Ψb-Ψv )
μx = VcosαTPP/RΩ
zv = -μz(Ψb-Ψv )+ ∫ (v/RΩ)dΨ Ψb
Ψv
μz =VsinαTPP/RΩ
yv = RsinΨv
Tip vortex geometry expressed by the prescribed wake model
Hybrid Method of Prescribed Wake Model/CFD (1/2)
B. G. van der Wall: Prediction of BVI Noise Radiation Variation Due to HHC
Using Advanced Prescribed Wake Methodology
Previous study (2012, DLR)
BVI
Δ2 [dB]
Error of prescribed wake model
influences on CFD error.
Overestimation of BVISPL
Overestimation
Error
5
Hybrid Method of Prescribed Wake Model/CFD (2/2)
When using the
hybrid method
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1st BVI 2nd BVI
3rd BVI 4th BVI
Flow ・For an improvement of the
hybrid method, it is
required to estimate the
change of vortex center
and its strength due to
the sequential BVI.
When using CFD
・ Difference of vortex center
between CFD and the hybrid
method affects to the accuracy
of BVI noise prediction.
Vorticity Magnitude
Rotor
Toward An Improvement of The Hybrid Method(1/2)
7
xv = RcosΨv+μx (Ψb-Ψv )
zv = -μz (Ψb-Ψv )+ ∫ (v/RΩ)dΨ Ψb
Ψv
Requirement of the modified prescribed wake model
+Δxv (Ψb-Ψv , Γ , ・ ・ ・ )
+Δzv (Ψb-Ψv , Γ , ・ ・ ・ )
yv = RsinΨv +Δyv (Ψb-Ψv , Γ , ・ ・ ・ )
Wake position to modify
Ω
Toward An Improvement of The Hybrid Method(2/2)
AVI: Airfoil-Vortex Interaction
・ It is promising approach to estimate
the change of vortex center location
and vortex circulation with 2-D AVI
simulations for development of the
modified prescribed wake model.
8
・ N u m e r i c a l s i m u l a t i o n o f AV I f o r
i mp rovemen t o f t he hyb r i d me thod
E s t i m a t i o n o f t h e c h a n g e o f v o r t e x
c e n t e r l o c a t i o n a n d v o r t e x
c i r c u l a t i o n d u e t o s e q u e n t i a l A V I
2 - D C F D s i m u l a t i o n c o m p o s e d o f
a s i n g l e v o r t e x a n d t w o a i r f o i l s