scholarly journals Moment-based estimation for the shape parameters of the Gamma-Gamma atmospheric turbulence model

2010 ◽  
Vol 18 (12) ◽  
pp. 12824 ◽  
Author(s):  
Ning Wang ◽  
Julian Cheng
Keyword(s):  
Atmospheric Turbulence ◽  
Turbulence Model ◽  
Shape Parameters

Distributed Turbulence Model with Rigorous Spatial Cross-Correlation for Simulation of Helicopter Flight in Atmospheric Turbulence

2019 ◽  
Vol 64 (4) ◽  
pp. 1-13
Author(s):  
Honglei Ji ◽  
Renliang Chen ◽  
Pan Li
Keyword(s):  
Atmospheric Turbulence ◽  
Turbulence Model ◽  
Cross Correlation ◽  
Turbulence Models ◽  
Flight Test ◽  
Longitudinal Direction ◽  
Flight Simulation ◽  
Quality Analysis ◽  
Frequency Range ◽  
Helicopter Flight

This paper presents a distributed turbulence model with rigorous spatial cross-correlation for helicopter flight simulation in atmospheric turbulence and for future handling-quality analysis. First, digital filters with longitudinal correlations of the von Kármán turbulence are developed to generate discrete turbulence velocity components. Meanwhile, transverse turbulence correlations are considered by relating the filters in different positions with mathematically rigorous spatial cross-correlation. Then, the distributions of the related filters on the transverse plane in front of helicopter and their velocity components in the longitudinal direction of airspeed, as well as turbulence models of helicopter aerodynamic surfaces, are established. Finally, a flight dynamics model coupled with the turbulence model is developed and validated against the flight-test data. The proposed model can achieve accurate real-time simulations of helicopter response to atmospheric turbulence in the frequency range of interest of handling qualities. The effect of transverse turbulence correlations on helicopter frequency response is also analyzed. The results show that the simulation model regardless of transverse turbulence correlations would aggravate the "rotor-to-body attenuation" effect of the main rotor and therefore underpredict the helicopter roll, pitch, and heave rate responses to atmospheric turbulence in the frequency range of interest.

Basic Pattern in Atmospheric Turbulence Model

2004 ◽  
Vol 41 (6) ◽  
pp. 845-848 ◽  
Author(s):  
Fu Zun-Tao ◽  
Zhang Lin ◽  
Liu Shi-Da ◽  
Liu Shi-Kuo
Keyword(s):  
Atmospheric Turbulence ◽  
Turbulence Model ◽  
Basic Pattern

scholarly journals Towards the monitoring of atmospheric turbulence model

2004 ◽  
Vol 414 (3) ◽  
pp. L33-L36 ◽  
Author(s):  
A. Ziad ◽  
J. Borgnino ◽  
F. Martin ◽  
J. Maire ◽  
D. Mourard
Keyword(s):  
Atmospheric Turbulence ◽  
Turbulence Model

SCALE EXPONENTS OF ATMOSPHERIC TURBULENCE UNDER DIFFERENT STRATIFICATIONS

Fractals ◽  
1996 ◽  
Vol 04 (01) ◽  
pp. 45-48 ◽  
Author(s):  
QIAN MINWEI ◽  
LIU SHIDA
Keyword(s):  
Surface Layer ◽  
Wavelet Analysis ◽  
Gravity Wave ◽  
Atmospheric Turbulence ◽  
Turbulence Model ◽  
Stable Stratification ◽  
Inertial Range ◽  
The State ◽  
Intermittent Turbulence ◽  
The Difference

Wavelet analysis is used to measure directly the scale exponents of atmospheric turbulence at inertial range under different stratifications. It is found that the average values of the scale exponents under different stratifications are clearly different and are all lower than the Kolmogorov 1941 value of 1/3. The difference shows that, according to the intermittent turbulence model, turbulence under stable stratification behaves more intermittently than under unstable stratification. The reason may be that the gravity wave, which could exist only under stable stratification, modulates the state of nocturnal surface layer and causes this kind of intermittence.

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