Estimation of Turbulent Vertical Velocity from Nonlinear Simulations of Aircraft Response

Sheu, Donglong; Lan, C. E.

doi:10.2514/1.c031190

Cited by 17 publications

(6 citation statements)

References 5 publications

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“…If λr is positive, the system is unstable; if it is negative, the system is stable [13]. represents the virtual mass effect and is particularly large in transonic flow to affect the plunging motion [28]. The magnitudes of C l .…”

Section: Numerical Results and Discussionmentioning

confidence: 99%

“…Airlines care about the vertical plunging mode of motion, which is not considered in classical flight dynamics. According to [28], in vertical plunging motion, the damping term is mainly related to Airlines care about the vertical plunging mode of motion, which is not considered in classical flight dynamics. According to [28], in vertical plunging motion, the damping term is mainly related to C z .…”

Section: Numerical Results and Discussionmentioning

confidence: 99%

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Quantitative Assessment of Dynamic Stability Characteristics for Jet Transport in Sudden Plunging Motion

Wang

Zheng

et al. 2022

Applied Sciences

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In this paper, we present a monitoring program of loss control prevention for airlines to enhance aviation safety and operational efficiency. The assessments of dynamic stability characteristics based on the approaches of oscillatory motion and eigenvalue motion modes for jet transport aircraft response to sudden plunging motions are demonstrated. A twin-jet transport aircraft encountering severe clear-air turbulence in transonic flight during the descending phase was examined as the study case. The flight results in sudden plunging motions with abrupt changes in attitude and gravitational acceleration (i.e., the normal load factor) are provided. Development of the required thrust and aerodynamic models with the flight data mining and the fuzzy logic modeling techniques was carried out. The oscillatory derivatives extracted from these aerodynamic models were then used in the study of variations in stability characteristics during the sudden plunging motion. The fuzzy logic aerodynamic models were utilized to estimate the nonlinear unsteady aerodynamics while performing numerical integration of flight dynamic equations. The eigenvalues of all motion modes were obtained during time integration. The positive real part of the eigenvalues is to indicate unstable motion. The dynamic stability characteristics during sudden plunging motion are easily judged by the values in positive or negative. The present quantitative assessment method is an innovation to examine possible mitigation concepts of accident prevention and promote the understanding of aerodynamic responses of the jet transport aircraft.

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Section: Numerical Results and Discussionmentioning

confidence: 99%

Section: Numerical Results and Discussionmentioning

confidence: 99%

Quantitative Assessment of Dynamic Stability Characteristics for Jet Transport in Sudden Plunging Motion

Wang

Zheng

et al. 2022

Applied Sciences

View full text Add to dashboard Cite

show abstract

“…The magnitudes oḟanḋhave significant variations anḋ < 0 in the period of = 7482.5 ∼ 7491 sec in Figure 7(b). It should be noted thaṫrepresents the virtual mass effect and is particularly large in transonic flow to affect the plunging motion [31]. The ( ) osc and ( ) osc are inadequate in oscillatory damping in the periods of = 7484 ∼ 7486 sec and = 7490 ∼ 7494 sec, as shown in Figure 7 = 7485 sec.…”

Section: Analysis Of Model Predictionsmentioning

confidence: 95%

Fuzzy Logic-Based Aerodynamic Modeling with Continuous Differentiability

Chang

2013

Mathematical Problems in Engineering

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This paper presents a modeling method based on a fuzzy-logic algorithm to establish aerodynamic models by using the datasets from flight data recorder (FDR). The fuzzy-logic aerodynamic models are utilized to estimate more accurately the nonlinear unsteady aerodynamics for a transport aircraft, including the effects of atmospheric turbulence. The main objective in this paper is to present the model development and the resulting models with continuous differentiability. The uncertainty and correlation of the data points are estimated and improved by monitoring a multivariable correlation coefficient in the modeling process. The latter is increased by applying a least square method to a set of data points to train a set of modeling coefficients. A commercial transport aircraft encountered severe atmospheric turbulence twice at transonic flight in descending phase is the study case in the present paper. The robustness and nonlinear interpolation capability of the fuzzy-logic algorithm are demonstrated in predicting the degradation in performance and stability characteristics of this transport in severe atmospheric turbulence with sudden plunging motion.

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“…However, it was found that the flight dynamic equations require reformulation to improve numerical damping and avoid numerical divergence (Sheu & Lan 2011). As a result of numerical integration, the turbulent vertical wind can also be estimated from the difference in the total as measured by the aircraft -sensor and the motion-produced by numerical integration.…”

Section: Flight Dynamic Applicationmentioning

confidence: 99%

“…As a result, the effect of parabolic shape functions would smooth out the variation. From a physical point of view, it is expected that in plunging motion the N C   -derivative, which basically represents the virtual mass effect in unsteady aerodynamics (Sheu & Lan, 2011), should vary sharply. Note that the dynamic derivative, N C   , is dimensionless (see below).…”

Section: Effects Of Membership Shape Functionsmentioning

confidence: 99%

Fuzzy-Logic Analysis of the FDR Data of a Transport Aircraft in Atmospheric Turbulence

Lan¹,

Chang²

2012

Fuzzy Logic - Emerging Technologies and Applications

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Estimation of Turbulent Vertical Velocity from Nonlinear Simulations of Aircraft Response

Cited by 17 publications

References 5 publications

Quantitative Assessment of Dynamic Stability Characteristics for Jet Transport in Sudden Plunging Motion

Quantitative Assessment of Dynamic Stability Characteristics for Jet Transport in Sudden Plunging Motion

Fuzzy Logic-Based Aerodynamic Modeling with Continuous Differentiability

Fuzzy-Logic Analysis of the FDR Data of a Transport Aircraft in Atmospheric Turbulence

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