Exact aerodynamic force decomposition and dynamic force derivatives in non linear flows

2017 ◽  
Author(s):  
Mario Ostieri ◽  
Benedetto Mele ◽  
Renato Tognaccini
Keyword(s):  
Aerodynamic Force ◽  
Dynamic Force ◽  
Non Linear ◽  
Linear Flows ◽  
Force Decomposition

GPR-based novel approach for non-linear aerodynamic modelling from flight data

2018 ◽  
Vol 123 (1259) ◽  
pp. 79-92
Author(s):  
A. Kumar ◽  
A. K. Ghosh
Keyword(s):  
Aerodynamic Force ◽  
Equations Of Motion ◽  
Gaussian Process Regression ◽  
Likelihood Estimation ◽  
Flight Data ◽  
Novel Approach ◽  
Non Linear ◽  
Research Aircraft ◽  
Novel Method ◽  
Aerodynamic Modelling

ABSTRACTIn this paper, a Gaussian process regression (GPR)-based novel method is proposed for non-linear aerodynamic modelling of the aircraft using flight data. This data-driven regression approach uses the kernel-based probabilistic model to predict the non-linearity. The efficacy of this method is examined and validated by estimating force and moment coefficients using research aircraft flight data. Estimated coefficients of aerodynamic force and moment using GPR method are compared with the estimated coefficients using maximum-likelihood estimation (MLE) method. Estimated coefficients from the GPR method are statistically analysed and found to be at par with estimated coefficients from MLE, which is popularly used as a conventional method. GPR approach does not require to solve the complex equations of motion. GPR further can be directed for the generalised applications in the area of aeroelasticity, load estimation, and optimisation.

scholarly journals On the aerodynamic forces on heaving and pitching airfoils at low Reynolds number

2017 ◽  
Vol 828 ◽  
pp. 395-423 ◽  
Author(s):  
M. Moriche ◽  
O. Flores ◽  
M. García-Villalba
Keyword(s):  
Aerodynamic Force ◽  
The Body ◽  
Body Motion ◽  
Fluid Inertia ◽  
Aerodynamic Forces ◽  
Noticeable Improvement ◽  
Large Amplitude Motions ◽  
Flow Circulation ◽  
The Mean ◽  
Force Decomposition

The influence that the kinematics of pitching and heaving 2D airfoils has on the aerodynamic forces is investigated using direct numerical simulations and a force decomposition algorithm. Large-amplitude motions are considered (of the order of one chord), with moderate Reynolds numbers and reduced frequencies of order $O(1)$, varying the mean pitch angle and the phase shift between the pitching and heaving motions. Our results show that the surface vorticity contribution (viscous effect) to the aerodynamic force is negligible compared with the contributions from the body motion (fluid inertia) and the vorticity within the flow (circulation). For the range of parameters considered here, the latter tends to be instantaneously oriented in the direction normal to the chord of the airfoil. Based on the results discussed in this paper, a reduced-order model for the instantaneous aerodynamic force is proposed, taking advantage of the force decomposition and the chord-normal orientation of the contribution from vorticity within the flow to the total aerodynamic force. The predictions of the proposed model are compared with those of a similar model from the literature, showing a noticeable improvement in the prediction of the mean thrust, and a smaller improvement in the prediction of the mean lift and the instantaneous force coefficients.

Tube Theory for Entangled Linear Polymers: Influence of Different Molecular Mechanisms in Non-Linear Flows

2008 ◽  
Author(s):  
Sunil Dhole ◽  
Adrien Leygue ◽  
Christian Bailly ◽  
Roland Keunings ◽  
Albert Co ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Linear Polymers ◽  
Non Linear ◽  
Linear Flows

Non-linear flows in porous media

1999 ◽  
Vol 86 (1-2) ◽  
pp. 229-252 ◽  
Author(s):  
Shijie Liu ◽  
Jacob H. Masliyah
Keyword(s):  
Porous Media ◽  
Flows In Porous Media ◽  
Non Linear ◽  
Linear Flows

Effects of slip on the non-linear flows of a third grade fluid

2010 ◽  
Vol 11 (1) ◽  
pp. 139-146 ◽  
Author(s):  
R. Ellahi ◽  
T. Hayat ◽  
F.M. Mahomed ◽  
S. Asghar
Keyword(s):  
Third Grade ◽  
Third Grade Fluid ◽  
Non Linear ◽  
Grade Fluid ◽  
Linear Flows

Dynamic Effects of Track Surface Condition on Vertical Wheel/Rail Forces and Energy Consumption

2010 ◽  
Author(s):  
Allan M. Zarembski ◽  
Clifford S. Bonaventura
Keyword(s):  
Energy Consumption ◽  
Quality Index ◽  
Graphical Form ◽  
Dynamic Force ◽  
Dynamic Effects ◽  
Track Geometry ◽  
Track Condition ◽  
Non Linear ◽  
Track Surface ◽  
Track Quality

As track geometry degrades, and in particular as track surface and cross-level (as defined by a Track Quality Index or TQI) degrades, railway vehicles going over that degraded track experience increased vertical dynamic behavior and increased vehicle/track interaction. This in turn translates into increased wheel/rail dynamic forces as well as increased energy (fuel) consumption. While this concept has been known for many years, there has been limited study of the direct relationships between the degree of track degradation (as quantified by a Track Quality Index type parameter) and the magnitude of the dynamic force and energy consumption increase. This paper presents a recent study on the dynamic effects of track surface geometry degradation, which has direct impact on maintenance practices, policies, and economics. Specifically, this paper presents the results of a series of analyses looking at the effect of increased track geometry degradation, as measured by a track geometry inspection vehicle, and quantified by a Track Quality Index (TQI). The effects examined include loss of energy and wasted fuel due to dissipation of energy in the vehicle suspension, as well as the increase in dynamic vertical force at the wheel/rail interface. The analyses used over 100 miles of US main line (Class 1) railroad track geometry data for a broad range of track conditions (and corresponding Track and Surface Quality Indices); together with a sophisticated multi-degree of freedom vehicle dynamics model to develop a relationship between track condition and dynamic effects. The results are a series of non-linear relationships between track condition, as defined by TQI, and energy loss in the suspension system, i.e. energy dissipation. A second set of non-linear relations was also developed between track condition, as defined by TQI, and dynamic force multiplier, i.e. the ratio of dynamic force to static wheel/rail load. The paper presents these results in both mathematical and graphical form.

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