Experimental Analysis of Impedance-Driven Reverse Flow Dynamics

2016 ◽  
Vol 819 ◽  
pp. 305-308
Author(s):  
V.C.C. Lee ◽  
Chang Hong Chai ◽  
Ming Chiat Law ◽  
S.K. Wee
Keyword(s):  
Experimental Analysis ◽  
Peak Flow ◽  
Reverse Flow ◽  
Excitation Frequency ◽  
Open Loop ◽  
Flow Dynamics ◽  
Driving Mechanism ◽  
Forward Peak ◽  
Dynamical Study ◽  
Impedance Pump

Impedance pump is a type of valveless pumping device, in which it utilizes a bio-inspired mechanism for pumping of fluid based on resonant wave interactions along a flexible media. By inducing a periodic asymmetrical compression on the flexible media will produce a unidirectional flow within the system. The impedance pump has many beneficial characteristics which make it an effective driving mechanism, especially for micro-fluidic systems. In addition, the wave-based mechanism through which pumping occurs infers many benefits in terms of simplicity of design and manufacturing. Adjustment of simple parameters such as the excitation frequency or compression location will reverse the direction of flow, providing a very versatile range of flow outputs. This paper describes the experimental analysis of such impedance-driven flow with emphasis on dynamical study of the reverse flow in open-loop environment. In this study, tapered section with converging steps is introduced at both ends of the flexible media to amplify the reverse flow. Study conducted shows that the reverse peak flow is rather significant with estimate of 23% lower than the forward peak flow. The flow dynamics on the other hand has shown to exhibit different characteristics as per the forward peak flow.

scholarly journals Performance Evaluation of a Resonant-integrated Pumping System

2018 ◽  
Vol 202 ◽  
pp. 02009
Author(s):  
Vincent Chieng-Chen Lee
Keyword(s):  
Performance Evaluation ◽  
Excitation Frequency ◽  
Pressure Head ◽  
Low Noise ◽  
Integrated System ◽  
Positive Outcomes ◽  
Pumping System ◽  
At Resonance ◽  
Impedance Pump ◽  
Maximum Amplification

Impedance pump is a simple valve-less pumping mechanism; it offers a low energy, low noise alternative at both macro- and micro-scale devices. It is also demonstrated to be a promising new technique for producing and amplifying net flow. There have been research studying the effects of series-connected impedance pump, where an increase in net flow is exhibited. In this study, an integrated system of conventional pump and impedance pump is introduced. This paper describes the performance evaluation of this integrated pumping system, with emphasis on the amount of amplification induced as a function of Womersley number (normalized excitation frequency) and normalized pressure head. Due to the nature of the resonant valve-less impedance pump, the integrated pumping system exhibits similar behaviour and characteristics as an impedance pump, such as the pulsatile nature of net flow. Results show positive outcomes where maximum amplification of 91.7% is demonstrated at resonance.

Computational and experimental analysis of the flow dynamics in a multi-swirler combustor

2002 ◽  
Author(s):  
F. Grinstein ◽  
T. Young ◽  
G. Li ◽  
E. Gutmark ◽  
G. Hsiao ◽  
...  
Keyword(s):  
Experimental Analysis ◽  
Flow Dynamics

Computational Study of Flow Resonances and Forces on a Cylinder Vibrating In-Line to a Steady Flow

2010 ◽  
Author(s):  
Lambros Kaiktsis ◽  
George S. Triantafyllou
Keyword(s):  
Oscillation Frequency ◽  
Computational Study ◽  
Oscillation Amplitude ◽  
Excitation Frequency ◽  
Spectral Element ◽  
Flow Dynamics ◽  
Chaotic Flow ◽  
Cylinder Diameter ◽  
Wide Range ◽  
Two Dimensional Flow

We present computational results of the flow dynamics and forces on a circular cylinder oscillating in-line with respect to a steady uniform stream. A wide range of oscillation frequencies is considered, from 0.5fs to 3fs, where fs is the natural Strouhal frequency of the Karman street. The oscillation amplitude is varied up to half the cylinder diameter. The Reynolds number value is 180, corresponding to two-dimensional flow. Simulations utilize a spectral element method. The computed flow states are characterized based on processed lift signals, and flow visualization. We find that the response of the flow is very sensitive to variations of the cylinder oscillation frequency. At low oscillation frequency, the lift signal and vortex patterns remain regular for low oscillation amplitudes, i.e. correspond to a 2S type of vortex street, and become complex at high oscillation amplitudes. Cylinder oscillation at the Strouhal frequency gives a window of chaotic flow at intermediate amplitudes, while at higher amplitudes 2S wakes are generated, with the sub-harmonic fs/2 and the higher harmonic 3fs/2 dominating the lift spectrum. Oscillation at twice the Strouhal frequency results in symmetric shedding, for oscillation amplitudes close to 30% of the cylinder diameter, and higher. Finally, at an oscillation frequency equal to three times the Strouhal frequency, the flow dynamics is very rich, characterized by “islands” of symmetric and asymmetric shedding at increasing oscillation amplitude. Chaotic flow is obtained only when the excitation frequency is equal to fs or to 3fs.

scholarly journals Experimental analysis of a water-pump driving mechanism using an orthogonal double-slider joint

2016 ◽  
Vol 3 (1) ◽  
pp. 15-00551-15-00551
Author(s):  
Takumi YOSHIZAWA ◽  
Jun NANGO ◽  
Toshiomi KOGUCHI
Keyword(s):  
Experimental Analysis ◽  
Driving Mechanism ◽  
Water Pump

scholarly journals An Experimental Analysis on the Effects of Stagger on the Aerodynamic Forces of Tandem Wings

AVIA ◽  
2021 ◽  
Vol 2 (2) ◽  
Author(s):  
Y Parlindungan ◽  
S Tobing
Keyword(s):  
Experimental Analysis ◽  
Numerical Study ◽  
Lift Coefficient ◽  
Angle Of Attack ◽  
Aerodynamic Performance ◽  
Open Loop ◽  
Aerodynamic Forces ◽  
Subsonic Wind Tunnel ◽  
Lift And Drag ◽  
Naca 0012

This study is inspired by the flapping motion of natural flyers: insects. Many insects have two pairs of wings referred as tandem wings. Literature review indicates that the effects of tandem wing are influenced by parameters such as stagger (the stream-wise distance between the aerodynamic center of the front and the rear airfoil), angle-of-attack and flow velocity. As a first stage, this study focuses on the effects of stagger (St) on the aerodynamic performance of tandem wings. A recent numerical study of stagger on tandem airfoils in turbulent flow (Re = 6000000) concluded that a larger stagger resulted in a decrease in lift force, and an increase in drag force. However, for laminar flow (Re = 2000), increasing the stagger was not found to be detrimental for aerodynamic performance. Another work also revealed that the maximum lift coefficient for a tandem configuration decreased with increasing stagger. The focus of this study is to perform an experimental analysis of tandem two-dimensional (2D) NACA 0012 airfoils. The two airfoils are set at the same angle-of-attack of 0° to 15° with 5° interval and three variations of stagger: 1c, 1.5c and 2c. The experiments are conducted using an open-loop-subsonic wind tunnel at a Reynolds number of 170000. The effects of St on the aerodynamic forces (lift and drag) are analyzed

Experimental Analysis of the Dynamic Characteristics of a Foil Thrust Bearing

2014 ◽  
Author(s):  
Franck Balducchi ◽  
Mihai Arghir ◽  
Romain Gauthier
Keyword(s):  
Dynamic Characteristics ◽  
Experimental Analysis ◽  
Dynamic Models ◽  
Thrust Bearing ◽  
Dynamic Stiffness ◽  
Excitation Frequency ◽  
Test Rig ◽  
Equivalent Damping ◽  
Start Up ◽  
Foil Thrust Bearing

The paper deals with the experimental analysis of the dynamic characteristics of a foil thrust bearing (FTB) designed following the specifications given by NASA in 2009. The start-up characteristics of the same foil bearing were investigated in a recently published paper. The test rig used for start-up measurements was adapted for dynamic measurements. The paper presents the test rig in detail as well as its identified dynamic models. Measurements of the dynamic characteristics of the bump foil structure were performed for static loads comprised between 30 N and 150 N while measurements for the FTB were performed at 35 krpm for 30 N, 60 N and 90 N. Excitation frequencies were comprised between 150 Hz and 750 Hz. Results showed that the dynamic stiffness of the FTB increase with excitation frequency while the equivalent damping decreases. Both stiffness and damping increase with the static load but are smaller at 35 krpm compared to 0 rpm.

CFD simulation and experimental analysis of flow dynamics and grinding performance of opposed fluidized bed air jet mill

2011 ◽  
Vol 98 (1-2) ◽  
pp. 94-105 ◽  
Author(s):  
M. Sri Raj Rajeswari ◽  
K.A.M. Azizli ◽  
S.F.S. Hashim ◽  
M.K. Abdullah ◽  
M. Abdul Mujeebu ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Experimental Analysis ◽  
Cfd Simulation ◽  
Flow Dynamics ◽  
Air Jet ◽  
Grinding Performance

Experimental Analysis of the Dynamic Characteristics of a Foil Thrust Bearing

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
Franck Balducchi ◽  
Mihai Arghir ◽  
Romain Gauthier
Keyword(s):  
Dynamic Characteristics ◽  
Experimental Analysis ◽  
Gas Turbines ◽  
Thrust Bearing ◽  
Dynamic Stiffness ◽  
Excitation Frequency ◽  
Equivalent Damping ◽  
Start Up ◽  
And Performance ◽  
Foil Thrust Bearing

This paper deals with the experimental analysis of the dynamic characteristics of a foil thrust bearing (FTB) designed according to specifications given by NASA scientists in 2009 (Dykas et al., 2009, “Design, Fabrication, and Performance of Foil Gas Thrust Bearings for Microturbomachinery Applications,” ASME J. Eng. Gas Turbines Power, 131(1), p. 012301). The present work details the new configuration of the same test rig that was used to test start-up characteristics of the aforementioned bearing (Balducchi et al., 2013, “Experimental Analysis of the Start-Up Torque of a Mildly Loaded Foil Thrust Bearing,” ASME J. Tribol., 135(3), p. 031703). The rig has been reconfigured to test dynamic characteristics. The dynamic characteristics of the bump foil structure were measured for static loads comprised between 30 N and 150 N while measurements for the FTB were performed at 35 krpm for 30 N, 60 N, and 90 N. Excitation frequencies were comprised between 150 Hz and 750 Hz. Results showed that the dynamic stiffness of the FTB increase with excitation frequency while the equivalent damping decreases. Both stiffness and damping increase with the static load but are smaller at 35 krpm compared to 0 rpm.

Experimental Analysis of Dynamic Characteristic for Automatic Tensioner

2014 ◽  
Vol 915-916 ◽  
pp. 49-52
Author(s):  
Xiang Kun Zeng
Keyword(s):  
Dynamic Characteristics ◽  
Experimental Analysis ◽  
Angular Displacement ◽  
Dynamic Stiffness ◽  
Excitation Frequency ◽  
Excitation Amplitude ◽  
Loss Angle ◽  
Load Torque ◽  
Dynamic Performances ◽  
Stiffness Loss

Experimental method and parameters to investigate the dynamic performances of an automatic tensioner are discussed. Parameters to evaluate the dynamic performances of a tensioner include dynamic stiffness, loss angle and equivalent viscous coefficient. Dynamic stiffness and loss angle can be measured directly, and the equivalent viscous coefficient can be calculated by torque-angular displacement loop which identified with the parameters including dynamic stiffness, loss angle, pre-load torque, pre-load angular displacement, excitation amplitude and excitation frequency. In this paper, the influences of excitation amplitude, excitation frequency and pre-load torque on the dynamic characteristics of tensioner are measured and investigated.

Sign in / Sign up

Export Citation Format

Share Document