scholarly journals A Method for Estimating Aircraft Vertical Acceleration and Eddy Dissipation Rate in Turbulent Flight

2020 ◽  
Vol 10 (19) ◽  
pp. 6798
Author(s):  
Zhenxing Gao ◽  
Debao Wang ◽  
Zhiwei Xiang
Keyword(s):  
Dissipation Rate ◽  
Aerodynamic Force ◽  
Wind Tunnel Test ◽  
Control Surface ◽  
Civil Aviation ◽  
Vertical Acceleration ◽  
Pitching Moment ◽  
Continuous Change ◽  
Adverse Influence ◽  
Modeling Data

Atmospheric turbulence is a typical risk that threatens the flight safety of civil aviation aircraft. A method of estimating aircraft’s vertical acceleration in turbulence is proposed. Based on the combination of wing and horizontal tail, the continuous change of aerodynamic force in turbulent flight is obtained by unsteady vortex ring method. Vortex rings are assigned on the mean camber surface to further improve the computing accuracy. The incremental aerodynamic derivatives of lift and pitching moment are developed, which can describe the turbulence effects on aircraft. Furthermore, a new acceleration-based eddy dissipation rate (EDR) algorithm was developed to estimate the turbulence severity. Compared with wind tunnel test data, the aerodynamic performance of the lifting surface was computed accurately. A further test on wing–tail combination showed that the computed pitching moment change due to control-surface deflections approaches the aircraft-modeling data. The continuous change of vertical acceleration at any longitudinal locations of aircraft is obtained in turbulent flight. Compared with traditional transfer function-based EDR algorithms, the proposed algorithm shows higher accuracy and stability. Furthermore, the adverse influence of aircraft maneuvering on EDR estimation is eliminated.

scholarly journals Estimation of Aircraft-Dependent Bumpiness Severity in Turbulent Flight

2021 ◽  
Vol 11 (4) ◽  
pp. 1796
Author(s):  
Haofeng Wang ◽  
Zhenxing Gao ◽  
Hongbin Gu ◽  
Kai Qi
Keyword(s):  
Aerodynamic Force ◽  
Estimation Method ◽  
Control Surface ◽  
Civil Aviation ◽  
Vertical Acceleration ◽  
Continuous Change ◽  
Lattice Method ◽  
Severity Estimation ◽  
Surface Deflections

Atmospheric turbulence threatens flight safety of civil aviation aircraft by inducing aircraft bumpiness. A severity estimation method of aircraft bumpiness in turbulent flight is explored according to in-situ Eddy Dissipation Rate (EDR) indicator. With the turbulence intensity derived from EDR value, a time series of longitudinal and vertical turbulence was generated according to von Karman turbulence model. In order to obtain the vertical acceleration response of aircraft, the continuous change of aerodynamic force on the assembly of wing and horizontal tail was computed by Unsteady Vortex Lattice Method (UVLM). The computing accuracy was improved by using semi-circle division and assigning the vortex rings on the mean camber surface. Furthermore, the adverse effects of control surface deflections on bumpiness severity estimation can be effectively removed by separating turbulence-induced and aircraft maneuvers-induced aerodynamic force change. After that, the variance of vertical acceleration, as the severity indicator of aircraft bumpiness, was obtained by Welch spectrum estimation. With the refined grid level, the pitching moment change due to control surface deflections can be solved accurately by UVLM. The instantaneous acceleration change obtained by UVLM approximates recorded acceleration data with better accuracy than linear transfer function model. A further test with a set of flight data on the same airway shows that compared with in-situ EDR indicator, the proposed method gives an aircraft-dependent estimation of bumpiness severity, which can not only be used to estimate in-situ bumpiness but also be applied to forecast the bumpiness severity of other different aircrafts.

scholarly journals Acceleration-Based In Situ Eddy Dissipation Rate Estimation with Flight Data

Atmosphere ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1247
Author(s):  
Zhenxing Gao ◽  
Haofeng Wang ◽  
Kai Qi ◽  
Zhiwei Xiang ◽  
Debao Wang
Keyword(s):  
Dissipation Rate ◽  
Civil Aviation ◽  
Vertical Acceleration ◽  
Acceleration Response ◽  
Lattice Method ◽  
Flight Data ◽  
Vortex Lattice Method ◽  
Vortex Lattices ◽  
Vertical Turbulence

Inducing civil aviation aircraft to bumpiness, atmospheric turbulence is a typical risk that seriously threatens flight safety. The Eddy Dissipation Rate (EDR) value, as an aircraft-independent turbulence severity indicator, is estimated by a vertical wind-based or aircraft vertical acceleration-based algorithm. Based on the flight data of civil aviation aircraft, the vertical turbulence component is obtained as the input of both algorithms. A new method of computing vertical acceleration response in turbulence is put forward through the Unsteady Vortex Lattice Method (UVLM). The lifting surface of the target aircraft is assumed to be a combination of wing and horizontal tail in a turbulent flight scenario. Vortex rings are assigned on the mean camber surface, forming a non-planar UVLM, to further improve the accuracy. Moreover, the neighboring vortex lattices are placed as close as possible to the structural edge of control surfaces. Thereby, a complete algorithm for estimating vertical acceleration and in situ EDR value from Quick Access Recorder (QAR) flight data is proposed. Experiments show that the aerodynamic performance is computed accurately by non-planar UVLM. The acceleration response by non-planar UVLM is able to track the recorded acceleration data with higher accuracy than that of the linear model. Different acceleration responses at different locations are also obtained. Furthermore, because the adverse effects of aircraft maneuvers are separated from turbulence-induced aircraft bumpiness, the new acceleration-based EDR algorithm shows better accuracy and stability.

scholarly journals A Comparison Study of EDR Estimates from the NLR and NCAR Algorithms

Atmosphere ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 132
Author(s):  
Jeffrey Chi Wai Lee ◽  
Christy Yan Yu Leung ◽  
Mang Hin Kok ◽  
Pak Wai Chan
Keyword(s):  
The Netherlands ◽  
Real Time ◽  
Dissipation Rate ◽  
Vertical Acceleration ◽  
Comparison Study ◽  
Time Data ◽  
Flight Data ◽  
Atmospheric Research ◽  
Real Time Data ◽  
Good Agreement

A comparison was made of two eddy dissipation rate (EDR) estimates based on flight data recorded by commercial flights. The EDR estimates from real-time data using the National Center for Atmospheric Research (NCAR) Algorithm were compared with the EDR estimates derived using the Netherlands Aerospace Centre (NLR) Algorithm using quick assess recorder (QAR) data. The estimates were found to be in good agreement in general, although subtle differences were found. The agreement between the two algorithms was better when the flight was above 10,000 ft. The EDR estimates from the two algorithms were also compared with the vertical acceleration experienced by the aircraft. Both EDR estimates showed good correlation with the vertical acceleration and would effectively capture the turbulence subjectively experienced by pilots.

scholarly journals Retrieving clear-air turbulence information from regular commercial aircraft using Mode-S and ADS-B broadcast

2015 ◽  
Vol 8 (11) ◽  
pp. 11817-11852 ◽  
Author(s):  
J. M. Kopeć ◽  
K. Kwiatkowski ◽  
S. de Haan ◽  
S. P. Malinowski
Keyword(s):  
Dissipation Rate ◽  
Vertical Acceleration ◽  
Background Wind ◽  
Commercial Aircraft ◽  
Processing Methods ◽  
Turbulence Measurements ◽  
Significant Potential ◽  
Air Turbulence ◽  
Research Aircraft ◽  
Comparison Of The Results

Abstract. Navigational information broadcast by commercial aircraft in the form of Mode-S and ADS-B messages can be considered a new and valid source of upper air turbulence measurements. A set of three processing methods is proposed and analysed using a quality record of turbulence encounters made by a research aircraft. The proposed methods are based on processing the vertical acceleration or the background wind into the eddy dissipation rate. All the necessary parameters are conveyed in the Mode-S/ADS-B messages. The comparison of the results of application of the processing against a reference eddy dissipation rate obtained using on-board accelerometer indicate a significant potential of those methods. The advantages and limitation of the presented approaches are discussed.

scholarly journals Analisis Sistem Kendali Terbang dengan Gain Scheduling Pada Pesawat Efek Permukaan

WARTA ARDHIA ◽  
2017 ◽  
Vol 43 (2) ◽  
pp. 141
Author(s):  
Sayuti Syamsuar
Keyword(s):  
Control System ◽  
Flight Control ◽  
Surface Effect ◽  
Wind Tunnel Test ◽  
Longitudinal Mode ◽  
Gain Scheduling ◽  
Control Surface ◽  
Root Locus ◽  
Output Response ◽  
Adaptive Flight Control

This paper provides an overview of the design of adaptive flight control system of wing in surface effect craft Lippisch configuration 8 passengers capacity during cruise in the low speed and low altitude. The control system will be used the control surface, such as elevator deflection as input and pitch angle deflection as output response or by using engine throttle setting as input and others output response in the longitudinal mode. This paper describes some methodologies control system method and analysis such as PID controller system with gain scheduling approach, and root locus method. The observable matrices (4 x 4) on the longitudinal mode that used in the control system became from aerodynamic derivative parameters of 8 seaters configuration that calculated by DATCOM numerical simulation or wind tunnel test result and dummy data.  Kajian ini merupakan rancangan sistem kendali terbang adaptif pada pesawat efek permukaan konfigurasi Lippisch kapasitas 8 orang saat terbang mendatar pada kecepatan dan ketinggian terbang rendah. Sistem kendali terbang yang digunakan, seperti defleksi elevator sebagai input dan defleksi sudut pitch sebagai respon output atau penggunaan defleksi throttle mesin sebagai input dan parameter respon output lain pada gerak matra longitudinal. Kajian menjelaskan penggunaan beberapa metodologi dan analisis sistem kendali terbang adaptif, seperti kontroler PID dengan pendekatan gain scheduling, dan metoda root locus. Matriks ruang keadaan berukuran (4 x 4) pada matra longitudinal yang digunakan pada sistem kendali terbang adaptif diperoleh dari parameter turunan aerodinamika hasil perhitungan numerik DATCOM atau hasil uji terowongan angin dan data dummy.

Transient Response Study on Rolling Effectiveness of Multiple Control Surfaces

2002 ◽  
Author(s):  
Deman Tang ◽  
Aiqin Li ◽  
Earl H. Dowell
Keyword(s):  
Transient Response ◽  
Three Dimensional ◽  
Wind Tunnel Test ◽  
Leading Edge ◽  
Control Surface ◽  
Multiple Control ◽  
Wing Model ◽  
Aerodynamic Model ◽  
Control Surfaces ◽  
Dry Friction Damping

In the present paper, a transient response study of the effectiveness of trailing and leading edge control surfaces has been made for a rolling wing-fuselage model. An experimental model and wind tunnel test are used to assess the theoretical results. The theoretical model includes the inherently nonlinear dry friction damping moment that is present between the spindle support and the experimental aeroelastic wing model. The roll trim equation of motion and the appropriate aeroelastic equations are solved for different combinations of leading and trailing edge control surface rotations using a reduced order aerodynamic model based upon the fluid eigenmodes of three dimensional vortex lattice aerodynamic theory. The present paper provides new insights into the transient dynamic behavior and design of an adaptive aeroelastic wing using trailing and leading edge control surfaces.

Effects of Ice Thickness on the Aerodynamic Characteristics of Crescent Shape Iced Conductors

2012 ◽  
Vol 166-169 ◽  
pp. 2696-2703 ◽  
Author(s):  
Dong Yan ◽  
Wen Juan Lou ◽  
Ming Feng Huang ◽  
Wei Lin
Keyword(s):  
Lift Force ◽  
Aerodynamic Force ◽  
Wind Tunnel Test ◽  
Aerodynamic Characteristics ◽  
Ice Thickness ◽  
Force Curve ◽  
Force Coefficients ◽  
Variation Patterns ◽  
The Difference ◽  
Force Characteristics

Aerodynamic characteristics of iced conductors were investigated by the wind tunnel test. Under the homogeneous turbulence of 5% intensity, aerodynamic force coefficients of single and bundled conductors were obtained at wind angles of 0°~180°. The variation patterns of aerodynamic forces on the iced conductors with respect to wind angels of attack were systematically studied for the ice thickness of 0.25, 0.5, 0.75 and 1 times of the conductor diameter. The difference of aerodynamic force characteristics for single and bundled conductors were identified and discussed. Based on the Den Hartog and Nigol’s mechanisms of galloping, the wind angle ranges sensitive to galloping were analyzed. The results show that lift and torsion force coefficients reach peak values at wind angles of 15°~20°. For bundled conductors, lift force curve is approximately agreed with the curve of single conductor. Drag force coefficients were smaller than these of single conductor at some wind angles. There are noticeably differences of torsion coefficients existed between bundled conductors and single conductor. According to two classical galloping mechanisms, wind angles of 15°~30°are critical for the galloping of iced conductors with crescent shapes.

Experimental Studies on Aerodynamic Characteristics of Pantograph System According to the Pantograph Cover Configurations for High Speed Train

2011 ◽  
Author(s):  
Yeongbin Lee ◽  
Minho Kwak ◽  
Kyu Hong Kim ◽  
Dong-Ho Lee
Keyword(s):  
Wind Tunnel ◽  
High Speed ◽  
Aerodynamic Drag ◽  
Aerodynamic Force ◽  
Experimental Studies ◽  
Wind Tunnel Test ◽  
Aerodynamic Characteristics ◽  
Experimental Models ◽  
High Speed Train ◽  
Drag And Lift

In this study, the aerodynamic characteristics of pantograph system according to the pantograph cover configurations for high speed train were investigated by wind tunnel test. Wind tunnel tests were conducted in the velocity range of 20∼70m/s with scaled experimental pantograph models. The experimental models were 1/4 scaled simplified pantograph system which consists of a double upper arm and a single lower arm with a square cylinder shaped panhead. The experimental model of the pantograph cover is also 1/4 scaled and were made as 4 different configurations. It is laid on the ground plate which modeled on the real roof shape of the Korean high speed train. Using a load cell, the aerodynamic force such as a lift and a drag which were acting on pantograph system were measured and the aerodynamic effects according to the various configurations of pantograph covers were investigated. In addition, the total pressure distributions of the wake regions behind the panhead of the pantograph system were measured to investigate the variations of flow pattern. From the experimental test results, we checked that the flow patterns and the aerodynamic characteristics around the pantograph systems are varied as the pantograph cover configurations. In addition, it is also found that pantograph cover induced to decrease the aerodynamic drag and lift forces. Finally, we proposed the aerodynamic improvement of pantograph cover and pantograph system for high speed train.

Workspace analysis and verification of cable-driven parallel mechanism for wind tunnel test

2016 ◽  
Vol 231 (6) ◽  
pp. 1012-1021 ◽  
Author(s):  
Xiaoguang Wang ◽  
Yunbo Hu ◽  
Qi Lin
Keyword(s):  
Wind Tunnel ◽  
Parallel Mechanism ◽  
Aerodynamic Force ◽  
Wind Tunnel Test ◽  
Special Kind ◽  
Parallel Robot ◽  
System Construction ◽  
Vector Projection ◽  
Workspace Analysis ◽  
Projection Strategy

Cable-driven parallel mechanism is a special kind of parallel robot in which traditional rigid links are replaced by actuated cables. This provides a new suspension method for wind tunnel test, in which an aircraft model is driven by a number of parallel cables to fulfil 6-DOF motion. The workspace of such a cable robot is limited due to the geometrical and unilateral force constraints, the investigation of which is important for applications requiring large flight space. This paper focuses on the workspace analysis and verification of a redundant constraint 6-DOF cable-driven parallel suspension system. Based on the system motion and dynamic equations, the geometrical interference (either intersection between two cables or between a cable and the aircraft) and cable tension restraint conditions are constructed and analyzed. The hyperplane vector projection strategy is used to solve the aircraft’s orientation and position workspace. Moreover, software ADAMS is used to check the workspace, and experiments are done on the prototype, which adopts a camera to monitor the actual motion space. In addition, the system construction is designed by using a built-in six-component balance to measure the aerodynamic force. The results of simulation and tests show a good consistency, which means that the restraint conditions and workspace solution strategy are valid and can be used to provide guidance for the cable-driven parallel suspension system’s application in wind tunnel tests.

Aerodynamic Forces of Stay Cables Incorporating in Flutier Analysis

2013 ◽  
Vol 438-439 ◽  
pp. 894-900
Author(s):  
Ke Jian Ouyang ◽  
Yi Long ◽  
Bi Cao Peng
Keyword(s):  
Aerodynamic Force ◽  
Three Dimensional ◽  
Wind Tunnel Test ◽  
Test Results ◽  
Stay Cable ◽  
Aerodynamic Forces ◽  
Stay Cables ◽  
Stiffness Matrices ◽  
Flutter Analysis ◽  
Sutong Bridge

With the length of stay cables close to 580m, only inclusion in aerodynamic forces of main deck cannot reflect the actual situation during wind-resistant design. The aerodynamic forces of stay cables should be considered in the three-dimensional flutter analysis of cable-stayed bridges. In this paper, mathematic expressions of unsteady aerodynamic force of stay cable were then derived in terms of aerodynamic damping and stiffness matrices. The above procedure is implemented into NACS by an independent module. As an example, the multimode flutter analysis of Sutong Bridge was conducted by using NACS. Fair agreement is achieved between the present numerical simulation and wind tunnel test results.

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