scholarly journals Flutter Analysis of a 3D Box-Wing Aircraft Configuration

2021 ◽  
Author(s):  
Amirhossein Ghasemikaram ◽  
Abbas Mazidi ◽  
S. Ahmad Fazelzadeh ◽  
Dieter Scholz
Keyword(s):  
Aerodynamic Force ◽  
Stability Boundary ◽  
Design Parameters ◽  
Governing Equations ◽  
Geometrical Properties ◽  
Aerodynamic Model ◽  
Flutter Analysis ◽  
Wing Sweep ◽  
Wing Structure ◽  
Good Agreement

The aim of this paper is to present a flutter analysis of a 3D Box-Wing Aircraft (BWA) configuration. The box wing structure is considered as consisting of two wings (front and rear wings) connected with a winglet. Plunge and pitch motions are considered for each wing and the winglet is modeled by a longitudinal spring. In order to exert the effect of the wing-joint interactions (bending and torsion coupling), two ends of the spring are located on the gravity centers of the wings tip sections. Wagner unsteady model is used to simulate the aerodynamic force and moment on the wing. The governing equations are extracted via Hamilton’s variational principle. To transform the resulting partial integro-differential governing equations into a set of ordinary differential equations, the assumed modes method is utilized. In order to confirm the aerodynamic model, the flutter results of a clean wing are compared and validated with the previously published results. Also, for the validation, the 3D box wing aircraft configuration flutter results are compared with MSC NASTRAN software and good agreement is observed. The effects of design parameters such as the winglet tension stiffness, the wing sweep and dihedral angles, and the aircraft altitude on the flutter velocity and frequency are investigated. The results reveal that physical and geometrical properties of the front and rear wings and also the winglet design have a significant influence on BWA aeroelastic stability boundary.

Ground Flutter Simulation Test Based on Reduced Order Modeling of Aerodynamics by CFD/CSD Coupling Method

2019 ◽  
Vol 11 (01) ◽  
pp. 1950008
Author(s):  
Binwen Wang ◽  
Xueling Fan
Keyword(s):  
Aerodynamic Force ◽  
Test System ◽  
Simulation Test ◽  
Robust Controller ◽  
Test Technique ◽  
Reduced Order ◽  
Aerodynamic Model ◽  
Flutter Boundary ◽  
Computational Fluid Dynamics Cfd ◽  
Good Agreement

Flutter is an aeroelastic phenomenon that may cause severe damage to aircraft. Traditional flutter evaluation methods have many disadvantages (e.g., complex, costly and time-consuming) which could be overcome by ground flutter test technique. In this study, an unsteady aerodynamic model is obtained using computational fluid dynamics (CFD) code according to the procedure of frequency domain aerodynamic calculation. Then, the genetic algorithm (GA) method is adopted to optimize interpolation points for both excitation and response. Furthermore, the minimum-state method is utilized for rational fitting so as to establish an aerodynamic model in time domain. The aerodynamic force is simulated through exciters and the precision of simulation is guaranteed by multi-input and multi-output robust controller. Finally, ground flutter simulation test system is employed to acquire the flutter boundary through response under a range of air speeds. A good agreement is observed for both velocity and frequency of flutter between the test and modeling results.

Flutter suppression of an aircraft wing with a flexibly mounted mass using magneto-rheological damper

2019 ◽  
Vol 234 (3) ◽  
pp. 827-839
Author(s):  
Amir Hossein Ghasemikaram ◽  
Abbas Mazidi ◽  
Mohammad Reza Fazel ◽  
Seyed Ahmad Fazelzadeh
Keyword(s):  
Differential Equations ◽  
State Feedback ◽  
Structural Model ◽  
Aerodynamic Force ◽  
Governing Equations ◽  
Aircraft Wing ◽  
Flutter Suppression ◽  
Flutter Analysis ◽  
Finite State ◽  
Magneto Rheological

Flutter analysis and suppression of an aircraft wing with a flexibly mounted external store using a magneto-rheological damper are investigated. The wing performs as a cantilever beam and the structural model, which incorporates bending-torsion flexibility, is used. A modified Bouc–Wen model is utilized in order to model the elastic connection between the store and the wing. The modified Peter’s finite-state loading is also considered to simulate the aerodynamic force and moment. The governing equations are obtained via Hamilton’s principle and assumed modes method is subsequently applied to transform the resulting partial differential equations into a set of ordinary differential equations. Numerical simulations are validated against several previously published papers by using a clean Goland wing. In order to control the vertical and rotational vibrations of the store and the wing, a state feedback controller and a compensator with full-order observer are designed. The performance of these controllers is compared together in several situations. Eventually, the performances are treated when disturbance is applied to the system. The results show that magneto-rheological damper’s performance is suitable for controlling the limit cycle oscillations of the wing and external store, in flutter condition.

Thermo-Electro-Mechanical Size-Dependent Buckling Response for Functionally Graded Graphene Platelet Reinforced Piezoelectric Cylindrical Nanoshells

2020 ◽  
Vol 20 (09) ◽  
pp. 2050100
Author(s):  
Zhen Zhao ◽  
Yiwen Ni ◽  
Shengbo Zhu ◽  
Zhenzhen Tong ◽  
Junlin Zhang ◽  
...  
Keyword(s):  
Functionally Graded ◽  
Response Analysis ◽  
Governing Equations ◽  
Electric Voltage ◽  
Stress Theory ◽  
Geometrical Properties ◽  
Size Dependent ◽  
Graphene Platelet ◽  
Effective Material Properties ◽  
Good Agreement

An accurate buckling response analysis for functionally graded graphene platelet (GPL) reinforced piezoelectric cylindrical nanoshells subject to thermo-electro-mechanical loadings is presented by a rigorous symplectic expansion approach. Three types of GPL reinforced patterns are considered, and the modified Halpin–Tsai model is employed to determine their effective material properties. By using Eringen’s nonlocal stress theory and Reissner’s shell theory, new governing equations are established in the Hamiltonian form. Exact solutions are expanded into symplectic series and three possible forms are derived. A comparison with the existing study is presented to validate the solution and very good agreement is observed. The effects of material and geometrical properties of GPLs, electric voltage and temperature rise on critical buckling stresses are investigated and discussed in detail.

Experimental and Numerical Analysis of a Sandwich Beam With Tip Mass

2018 ◽  
Author(s):  
E. F. Joubaneh ◽  
O. R. Barry ◽  
D. C. D. Oguamanam
Keyword(s):  
Numerical Analysis ◽  
Sandwich Panel ◽  
Equations Of Motion ◽  
Mathematical Formulation ◽  
Sandwich Beam ◽  
Design Parameters ◽  
Governing Equations ◽  
Parametric Studies ◽  
Tip Mass ◽  
Good Agreement

This paper presents experimental and numerical analyses of a vibrating sandwich beam with a tip mass. The mathematical formulation is based on higher order sandwich panel theory (HSAPT) and the governing equations of motion and boundary conditions are obtained using Hamilton’s principle. General Differential Quadrature (GDQ) is employed to solve the system governing equations of motion. Experiments are carried out to validate the proposed formulation and the results show very good agreement. Parametric studies are conducted to investigate the influence of key design parameters on the natural frequency and vibration response of the system.

Effect of design parameters on stresses occurring at the tooth root in a spur gear pressed on a shaft

2021 ◽  
pp. 095440892199529
Author(s):  
Fatih Güven
Keyword(s):  
Internal Pressure ◽  
Tangential Stress ◽  
Spur Gear ◽  
Design Parameters ◽  
Interference Fit ◽  
Gear Design ◽  
Compact Design ◽  
Fit Tolerance ◽  
Moderate Stress ◽  
Good Agreement

Gears are commonly used in transmission systems to adjust velocity and torque. An integral gear or an interference fit could be used in a gearbox. Integral gears are mostly preferred as driving gear for a compact design to reduce the weight of the system. Interference fit makes the replacement of damaged gear possible and re-use of the shaft compared to the integral shaft. However, internal pressure occurs between mating surfaces of the components mated. This internal pressure affects the stress distribution at the root and bottom land of the gear. In this case, gear parameters should be re-considered to assure gear life while reducing the size of the gear. In this study, interference fitted gear-shaft assembly was examined numerically. The effects of rim thickness, profile shifting, module and fit tolerance on bending stress occurring at the root of the gear were investigated to optimize gear design parameters. Finite element models were in good agreement with analytical solutions. Results showed that the rim thickness of the gear is the main parameter in terms of tangential stress occurring at the bottom land of the gear. Positive profile shifting reduces the tangential stress while the pitch diameter of the gear remains constant. Also, lower tolerance class could be selected to moderate stress for small rim thickness.

scholarly journals A Shock Mitigation of Pedestrian-Vehicle Impact Using Active Hood Lift System: Deploying Time Investigation

2016 ◽  
Vol 2016 ◽  
pp. 1-17 ◽  
Author(s):  
Tae-Hoon Lee ◽  
Gun-Ha Yoon ◽  
Seung-Bok Choi
Keyword(s):  
Response Time ◽  
Design Parameters ◽  
Passenger Vehicle ◽  
Governing Equations ◽  
Total Response Time ◽  
Shock Mitigation ◽  
Vehicle Impact ◽  
Driving Speed ◽  
Working Principle ◽  
Principal Design

This paper investigates the deploying time (or response time) of an active hood lift system (AHLS) of a passenger vehicle activated by gunpowder actuator. In this work, this is accomplished by changing principal design parameters of the latch part mechanism of the hood system. After briefly introducing the working principle of the AHLS operated by the gunpowder actuator, the governing equations of the AHLS are formulated for each different deploying motion. Subsequently, using the governing equations, the response time for deploying the hold lift system is determined by changing several geometric distances such as the distance from the rotational center of the pop-up guide to the point of the latch in the axial and vertical directions. Then, a comparison is made of the total response time to completely deploy the hood lift system with the existing conventional AHLS and proposed AHLS. In addition, the workable driving speed of the proposed AHLS is compared with the conventional one by changing the powder volume of the actuator.

Analytical and Experimental Flutter Analysis of a Typical Wing Section Carrying a Flexibly Mounted Unbalanced Engine

2019 ◽  
Vol 19 (02) ◽  
pp. 1950013 ◽  
Author(s):  
A. S. Mirabbashi ◽  
A. Mazidi ◽  
M. M. Jalili
Keyword(s):  
Stability Domain ◽  
Governing Equations ◽  
Lagrange Equations ◽  
Wing Section ◽  
Unbalanced Force ◽  
Engine Thrust ◽  
Finite State Model ◽  
Flutter Analysis ◽  
Finite State ◽  
The Stability

In this paper, both experimental and analytical flutter analyses are conducted for a typical 5-degree of freedon (5DOF) wing section carrying a flexibly mounted unbalanced engine. The wing flexibility is simulated by two torsional and longitudinal springs at the wing elastic axis. One flap is attached to the wing section by a torsion spring. Also, the engine is connected to the wing by two elastic joints. Each joint is simulated by a spring and damper unit to bring the model close to reality. Both the torsional and longitudinal motions of the engine are considered in the aeroelastic governing equations derived from the Lagrange equations. Also, Peter’s finite state model is used to simulate the aerodynamic loads on the wing. Effects of various engine parameters such as position, connection stiffness, mass, thrust and unbalanced force on the flutter of the wing are investigated. The results show that the aeroelastic stability region is limited by increasing the engine mass, pylon length, engine thrust and unbalanced force. Furthermore, increasing the damping and stiffness coefficients of the engine connection enlarges the stability domain.

Aerodynamic Similarity Principles and Scaling Laws for Windmilling Fans

2018 ◽  
Author(s):  
Dilip Prasad
Keyword(s):  
Rotational Speed ◽  
Pressure Loss ◽  
Scaling Laws ◽  
Dynamic Pressure ◽  
Stagnation Pressure ◽  
Design Parameters ◽  
Similarity Parameter ◽  
Wide Range ◽  
Simulation Results ◽  
Good Agreement

Windmilling requirements for aircraft engines often define propulsion and airframe design parameters. The present study is focused is on two key quantities of interest during windmill operation: fan rotational speed and stage losses. A model for the rotor exit flow is developed, that serves to bring out a similarity parameter for the fan rotational speed. Furthermore, the model shows that the spanwise flow profiles are independent of the throughflow, being determined solely by the configuration geometry. Interrogation of previous numerical simulations verifies the self-similar nature of the flow. The analysis also demonstrates that the vane inlet dynamic pressure is the appropriate scale for the stagnation pressure loss across the rotor and splitter. Examination of the simulation results for the stator reveals that the flow blockage resulting from the severely negative incidence that occurs at windmill remains constant across a wide range of mass flow rates. For a given throughflow rate, the velocity scale is then shown to be that associated with the unblocked vane exit area, leading naturally to the definition of a dynamic pressure scale for the stator stagnation pressure loss. The proposed scaling procedures for the component losses are applied to the flow configuration of Prasad and Lord (2010). Comparison of simulation results for the rotor-splitter and stator losses determined using these procedures indicates very good agreement. Analogous to the loss scaling, a procedure based on the fan speed similarity parameter is developed to determine the windmill rotational speed and is also found to be in good agreement with engine data. Thus, despite their simplicity, the methods developed here possess sufficient fidelity to be employed in design prediction models for aircraft propulsion systems.

Design on Parameterized Drafting System of Centrifugal Fan

2010 ◽  
Vol 34-35 ◽  
pp. 192-196
Author(s):  
Jiang Zhu ◽  
Limin Chen ◽  
Ping Yuan Xi
Keyword(s):  
Aerodynamic Force ◽  
Geometric Parameters ◽  
Rapid Response ◽  
Design Parameters ◽  
Centrifugal Fan ◽  
Aerodynamic Design ◽  
Key Factors ◽  
Fan Speed ◽  
Force Calculation

The impeller is the important pneumatic part of centrifugal fan, and its structure performances are key factors which affect the whole performances of fan. The CAD module of centrifugal fan can realize the automation of aerodynamic force calculation. According to demands, computer can automatically complete aerodynamic force calculation and further determine major geometric parameters of impeller of fan. Speed coefficient and diametral quotient are two important parameters reflecting the character of ventilating fan. The relation curve between the speed coefficient and diametral quotient of various fans is plotted in this paper. The CAD module of impeller of centrifugal fan can realize such functions as aerodynamic design and parameterization drawing of impeller, and can accomplish rapid response from receiving design parameters to profiled impeller of fan, so that it can improve the quality of drawing.

Aerodynamic Similarity Principles and Scaling Laws for Windmilling Fans

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Dilip Prasad
Keyword(s):  
Rotational Speed ◽  
Pressure Loss ◽  
Scaling Laws ◽  
Dynamic Pressure ◽  
Stagnation Pressure ◽  
Design Parameters ◽  
Similarity Parameter ◽  
Wide Range ◽  
Simulation Results ◽  
Good Agreement

Windmilling requirements for aircraft engines often define propulsion and airframe design parameters. The present study is focused on two key quantities of interest during windmill operation: fan rotational speed and stage losses. A model for the rotor exit flow is developed that serves to bring out a similarity parameter for the fan rotational speed. Furthermore, the model shows that the spanwise flow profiles are independent of the throughflow, being determined solely by the configuration geometry. Interrogation of previous numerical simulations verifies the self-similar nature of the flow. The analysis also demonstrates that the vane inlet dynamic pressure is the appropriate scale for the stagnation pressure loss across the rotor and splitter. Examination of the simulation results for the stator reveals that the flow blockage resulting from the severely negative incidence that occurs at windmill remains constant across a wide range of mass flow rates. For a given throughflow rate, the velocity scale is then shown to be that associated with the unblocked vane exit area, leading naturally to the definition of a dynamic pressure scale for the stator stagnation pressure loss. The proposed scaling procedures for the component losses are applied to the flow configuration of Prasad and Lord (2010). Comparison of simulation results for the rotor-splitter and stator losses determined using these procedures indicates very good agreement. Analogous to the loss scaling, a procedure based on the fan speed similarity parameter is developed to determine the windmill rotational speed and is also found to be in good agreement with engine data. Thus, despite their simplicity, the methods developed here possess sufficient fidelity to be employed in design prediction models for aircraft propulsion systems.

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