Reynolds-averaged Navier-Stokes Study of the Shock-buffet Instability Mechanism

Iovnovich, M.L.; Raveh, Daniella E.

doi:10.2514/6.2011-2078

Cited by 20 publications

(43 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The numerical grid is a C-type structured mesh of size 369 × 85 and appropriate cell spacing perpendicular to the airfoil surface for Y + ≈ 1. This computational model was well validated in a previous study [11] Figure 1 shows the pitching moment coecient time history, and frequency content at these ow conditions.…”

Section: Computational Setup and Instability Boundariesmentioning

confidence: 85%

Aeroelastic Responses of Spring-suspended Airfoil Systems in Transonic Buffeting Flows

Raveh¹,

Dowell²

2012

53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials ConferenceSelf Cite

0
0
0
0

View full text Add to dashboard Cite

Computer simulations are performed to determine the responses of a single DOF pitch airfoil system, as well as those of a two DOF pitch-and-heave system, in bueting ows. The bueting ow exhibits shock-wave oscillations of a unique frequency that occurs for some combinations of mean ow angle of attack and transonic Mach numbers. It was found that frequency lock-in may occur, depending on the relationship between the buet and structural frequencies. Following frequency lock-in the system response rapidly increases until reaching limit-cycle oscillations. Synchronization of the transonic aerodynamic buet phenomenon and the structural elastic modes provides a physical mechanism that may be responsible for some aircraft transonic LCO occurrences. It is distinctly dierent from a utter mechanism, leading to LCO, as discussed in the manuscript. Nomenclature a ∞ = speed of sound, m/s C L = airfoil lift coecient b = half chord length, m c = chord length, m f = frequency, Hz f = 2πf c/U ∞ = reduced frequencȳ f sb = 2πf c/U ∞ = shock-buet reduced frequency M ∞ = free-stream Mach number R ∞ = free-stream Reynolds number, based on chord t = physical time, s t = nondimensional time U ∞ = far-eld velocity, m/s Y + = dimensionless wall distance α ∞ = free-stream angle of attack, deg ∆C L = lift coecient peak-to-peak amplitude ∆t = nondimensional computational time step

show abstract

Section: Computational Setup and Instability Boundariesmentioning
confidence: 85%

Aeroelastic Responses of Spring-suspended Airfoil Systems in Transonic Buffeting Flows
Raveh¹,
Dowell²
2012
53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials ConferenceSelf Cite
0
0
0
0
View full text Add to dashboard Cite

show abstract

“…In a previous study, Iovnovich and Raveh [21] revisited the physical mechanism of the secondtype buet by exploring the variations of ow properties during a single buet cycle on three dierent airfoils, suggesting the essential link between the source of instability and the geometrical shape of the airfoil. Figures 1-2 show shock-buet simulation results on the RA16SC1 2D airfoil.…”

Section: D Buet Analysis Of the Ra16sc1 Airfoilmentioning
confidence: 99%

3D and Finite-wing Effects on the Shock-buffet Instability Mechanism
Iovnovich¹,
Raveh²
2012
53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials ConferenceSelf Cite
1
0
2
0
View full text Add to dashboard Cite

A study of the transonic shock-buet ow instability phenomena is presented.Reynolds-averaged Navier-Stokes simulations of four wing congurations are conducted at sock-buet ow conditions. The simulated congurations include nite, innite, straight and swept 3D wing models. Based on the results, the eects of 3D ow and wing niteness on the shock-buet phenomena characteristics are identied. The shock motion typical frequencies, amplitudes, periodicity, continuity and harmonization characteristics are found to be aected by the studied eects. Nevertheless, the instability fundamental mechanism was shown to remain similar to its 2D nature. It was indicated that the previously suggested necessary criteria for shock-buet onset in terms of shock position and ow separations remained relevant for the studied congurations. Swept wings with a tip chord that is parallel to the root chord were found less likely to experience shock-buet compared to similar wings with rotated tip planes.Two unsteady phenomena which are characterized by typical frequencies which are considerably higher than the shock-buet typical frequencies were observed in this study. Nomenclature a ∞ = speed of sound, m/s AR = wing aspect ratio b = wing span, m C L = airfoil lift coecient C p = pressure coecient c = chord length, m f = shock-buet frequency, Hz f = 2πf c/U ∞ = shock-buet reduced frequency I = computational domain index in the chord direction J = computational domain index in the span direction K = computational domain index in the surface normal direction M ∞ = free-stream Mach number R ∞ = free-stream Reynolds number, based on chord t = physical time, s t = a∞t c = nondimensional time U ∞ = free-stream velocity, m/s α = angle of attack, deg α i = induced angle of attack, deg α ∞ = free-stream angle of attack, deg ∆C L = lift coecient amplitude ∆X s = shock travel distance normalized to the chord length ∆t = nondimensional computational time step τ = mean-ow equations ctitious computational time step τ t = turbulence equations ctitious computational time step y + = dimensionless wall distance X = chordwise coordinate normalized to the chord length Y = spanwise coordinate normalized to the chord length 2 Downloaded by MONASH UNIVERSITY on November 26, 2014 | http://arc.aiaa.org |

show abstract

“…Iovnovich and Raveh [5] studied the oscillatory shock-buffet of the NACA-0012 and NACA-64A204 airfoils and showed that these oscillations occur and diminish over a range of attack angle in transonic flow. For example, it was shown that at Mach 0.75, the shock-buffet instability for the NACA-64A204 occurs between the onset attack angle of 5.1 degree and offset angle of 8.0 degree.…”

Section: Simulation Of Shock Around Airfoilmentioning
confidence: 99%

Front Tracking on Problems of US Air Force Interests SFFP (Preprint)
Li¹,
Moore²
2013
0
0
0
0
View full text Add to dashboard Cite

Reynolds-averaged Navier-Stokes Study of the Shock-buffet Instability Mechanism

Cited by 20 publications

References 25 publications

Aeroelastic Responses of Spring-suspended Airfoil Systems in Transonic Buffeting Flows

Aeroelastic Responses of Spring-suspended Airfoil Systems in Transonic Buffeting Flows

3D and Finite-wing Effects on the Shock-buffet Instability Mechanism

Front Tracking on Problems of US Air Force Interests SFFP (Preprint)

Contact Info

Product

Resources

About