Chirality-dependent asymmetric vortex core structures in a harmonic excitation mode

2020 ◽  
Vol 117 (4) ◽  
pp. 042401
Author(s):  
Hee-Sung Han ◽  
Sooseok Lee ◽  
Dae-Han Jung ◽  
Myeonghwan Kang ◽  
Ki‐Suk Lee
Keyword(s):  
Vortex Core ◽  
Harmonic Excitation ◽  
Asymmetric Vortex ◽  
Excitation Mode

ON THE NOx EMISSION LEVELS OF AN ASYMMETRIC VORTEX FLAME COMBUSTOR

2013 ◽  
Vol 12 (12) ◽  
pp. 2473-2478 ◽  
Author(s):  
Khalid M. Saqr ◽  
Mazlan Abdul Wahid
Keyword(s):  
Nox Emission ◽  
Asymmetric Vortex

Stagnation point flow in a vortex core

Tellus ◽  
1975 ◽  
Vol 27 (3) ◽  
pp. 269-280 ◽  
Author(s):  
L. Hatton
Keyword(s):  
Stagnation Point ◽  
Vortex Core ◽  
Stagnation Point Flow

scholarly journals Asymmetric vortex shedding in the wake of an abruptly expanding annular jet

2021 ◽  
Vol 62 (4) ◽  
Author(s):  
Maarten Vanierschot ◽  
Mustafa Percin ◽  
Bas W. van Oudheusden
Keyword(s):  
Vortex Shedding ◽  
Asymmetric Vortex ◽  
Annular Jet

scholarly journals Nonlinear vibration of knitted spacer fabric under harmonic excitation

2020 ◽  
Vol 15 ◽  
pp. 155892502098356
Author(s):  
Fuxing Chen ◽  
Hong Hu
Keyword(s):  
Nonlinear Vibration ◽  
Harmonic Balance Method ◽  
Harmonic Excitation ◽  
Polyurethane Foams ◽  
Excitation Level ◽  
Harmonic Amplitude ◽  
Damping Force ◽  
Spacer Fabric ◽  
Fabric System ◽  
Quadratic Stiffness

Knitted spacer fabrics can be an alternative material to typical rubber sponges and polyurethane foams for the protection of the human body from vibration exposure, such as automotive seat cushions and anti-vibration gloves. To provide a theoretical basis for the understanding of the nonlinear vibration behavior of the mass-spacer fabric system under harmonic excitation, experimental, analytical and numerical methods are used. Different from a linear mass-spring-damper vibration model, this study builds a phenomenological model with the asymmetric elastic force and the fractional derivative damping force to describe the periodic solution of the mass-spacer fabric system under harmonic excitation. Mathematical expression of the harmonic amplitude versus frequency response curve (FRC) is obtained using the harmonic balance method (HBM) to solve the equation of motion of the system. Parameter values in the model are estimated by performing curve fit between the modeled FRC and the experimental data of acceleration transmissibility. Theoretical analysis concerning the influence of varying excitation level on the FRCs is carried out, showing that nonlinear softening resonance turns into nonlinear hardening resonance with the increase of excitation level, due to the quadratic stiffness term and the cubic stiffness term in the model, respectively. The quadratic stiffness term also results in biased vibration response and causes an even order harmonic distortion. Besides, the increase of excitation level also results in elevated peak transmissibility at resonance.

scholarly journals Vibration Equation of Fractional Order Describing Viscoelasticity and Viscous Inertia

Open Physics ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 850-856 ◽  
Author(s):  
Jun-Sheng Duan ◽  
Yun-Yun Xu
Keyword(s):  
Fractional Derivative ◽  
Fractional Order ◽  
Fractional Derivatives ◽  
Harmonic Excitation ◽  
Steady State Response ◽  
Vibration System ◽  
Derivative Operator ◽  
Vibration Equation ◽  
State Response ◽  
Frequency Relation

Abstract The steady state response of a fractional order vibration system subject to harmonic excitation was studied by using the fractional derivative operator ${}_{-\infty} D_t^\beta,$where the order β is a real number satisfying 0 ≤ β ≤ 2. We derived that the fractional derivative contributes to the viscoelasticity if 0 < β < 1, while it contributes to the viscous inertia if 1 < β < 2. Thus the fractional derivative can represent the “spring-pot” element and also the “inerterpot” element proposed in the present article. The viscosity contribution coefficient, elasticity contribution coefficient, inertia contribution coefficient, amplitude-frequency relation, phase-frequency relation, and influence of the order are discussed in detail. The results show that fractional derivatives are applicable for characterizing the viscoelasticity and viscous inertia of materials.

Sign in / Sign up

Export Citation Format

Share Document