A valveless piezoelectric micropump with a Coanda jet element

2015 ◽  
Vol 230 ◽  
pp. 74-82 ◽  
Author(s):  
Song Yang ◽  
Xiuhua He ◽  
Shouqi Yuan ◽  
Jiawei Zhu ◽  
Zhidan Deng
Keyword(s):  
Coanda Jet

Numerical Studies of the Effects of Active and Passive Circulation Enhancement Concepts on Wind Turbine Performance

2006 ◽  
Vol 128 (4) ◽  
pp. 432-444 ◽  
Author(s):  
Chanin Tongchitpakdee ◽  
Sarun Benjanirat ◽  
Lakshmi N. Sankar
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Turbine Rotor ◽  
Horizontal Axis Wind Turbine ◽  
Trailing Edge ◽  
Low Wind Speed ◽  
Gurney Flap ◽  
Coanda Jet

The aerodynamic performance of a wind turbine rotor equipped with circulation enhancement technology (trailing-edge blowing or Gurney flaps) is investigated using a three-dimensional unsteady viscous flow analysis. The National Renewable Energy Laboratory Phase VI horizontal axis wind turbine is chosen as the baseline configuration. Experimental data for the baseline case is used to validate the flow solver, prior to its use in exploring these concepts. Calculations have been performed for axial and yawed flow at several wind conditions. Results presented include radial distribution of the normal and tangential forces, shaft torque, root flap moment, and surface pressure distributions at selected radial locations. At low wind speed (7m∕s) where the flow is fully attached, it is shown that a Coanda jet at the trailing edge of the rotor blade is effective at increasing circulation resulting in an increase of lift and the chordwise thrust force. This leads to an increased amount of net power generation compared to the baseline configuration for moderate blowing coefficients (Cμ⩽0.075). A passive Gurney flap was found to increase the bound circulation and produce increased power in a manner similar to Coanda jet. At high wind speed (15m∕s) where the flow is separated, both the Coanda jet and Gurney flap become ineffective. The effects of these two concepts on the root bending moments have also been studied.

Unsteady Aerodynamic Flow Investigation Around a Simplified Square-Back Road Vehicle With Drag Reduction Devices

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Bahram Khalighi ◽  
Kuo-Huey Chen ◽  
G. Iaccarino
Keyword(s):  
Drag Reduction ◽  
Three Dimensional ◽  
Common Element ◽  
Road Vehicle ◽  
Flow Investigation ◽  
Upward Deflection ◽  
Unsteady Rans ◽  
The Common ◽  
Shedding Frequency ◽  
Coanda Jet

The unsteady flow around a simplified road vehicle model with and without drag reduction devices is investigated. The simulations are carried out using the unsteady RANS in conjunction with the v2-f turbulence model. The corresponding experiments are performed in a small wind tunnel which includes pressure and velocity fields measurements. The devices are add-on geometry parts (a box with a cavity and, boat-tail without a cavity) which are attached to the back of the square-back model to improve the pressure recovery and reduce the flow unsteadiness. The results show that the recirculation regions at the base are shortened and weakened and the base pressure is significantly increased by the devices which lead to lower drag coefficients (up to 30% reduction in drag). Also, the results indicate a reduction of the turbulence intensities in the wake as well as a rapid upward deflection of the underbody flow with the devices in place. A reduction of the unsteadiness is the common element of the devices studied. The baseline configuration (square-back) exhibits strong three-dimensional flapping of the wake. The main shedding frequency captured agrees well with the available experimental data. Comparisons with the measurements show that the simulations agree reasonably well with the experiments in terms of drag and the flow structures. Finally, a blowing system (Coanda jet) is investigated numerically. In this case a drag reduction of up to 50% is realized.

Numerical Study on the Underexpanded Coanda Jet

1997 ◽  
Vol 34 (5) ◽  
pp. 641-647 ◽  
Author(s):  
Keisuke Sawada ◽  
Kengo Asami
Keyword(s):  
Numerical Study ◽  
Coanda Jet

Numerical simulation of circulation control turbine cascade with Coanda jet and counter-flow blowing at high Mach numbers

2017 ◽  
Vol 121 (1243) ◽  
pp. 1239-1260 ◽  
Author(s):  
Y. Feng ◽  
Y. Song ◽  
F. Chen
Keyword(s):  
Guide Vane ◽  
Inlet Guide Vane ◽  
Circulation Control ◽  
Turbine Cascade ◽  
Flow Conditions ◽  
Suction Surface ◽  
Counter Flow ◽  
Flow Angle ◽  
High Mach ◽  
Coanda Jet

ABSTRACTThe performance of a circulation-control inlet guide vane that makes use of the Coanda effect was studied numerically in a high Mach number turbine cascade. The effect of different shapes (elliptic and circular) of the Coanda surface at the blade trailing edge was investigated by implementing both a Coanda jet and a counter-flow blowing. Under high subsonic flow conditions, with a total blowing ratio of 3% of the mainstream, the circulation control cascade can reach the same performance as the reference stator with a 13.5% reduction in the axial chord length, with minimal increase of the energy loss coefficient. The Coanda surfaces with small curvature are more efficient in entraining the mainstream flow, and they achieve better aerodynamic performance. The wall attachment of the Coanda jet is improved by employing counter-flow blowing, resulting in a slight increase of both the exit flow angle and the expansion ratio. Under supersonic flow conditions at the cascade exit, it is more difficult for the circulation control cascade to reach the appropriate flow turning due to a premature shock wave, which is absent in the original cascade until the very end of the suction surface.

Design of a supersonic Coanda jet nozzle

1984 ◽  
Author(s):  
P. BEVILAQUA ◽  
J. LEE
Keyword(s):  
Jet Nozzle ◽  
Coanda Jet

210 Classification of Fine Solid Particle by Coanda Jet Flow

2000 ◽  
Vol 2000.49 (0) ◽  
pp. 77-78
Author(s):  
Toshihiko Shakouchi ◽  
Toshitake Ando ◽  
Koji Hase ◽  
Satoshi Terashima
Keyword(s):  
Solid Particle ◽  
Jet Flow ◽  
Coanda Jet

Computational evaluation of geometric effects on aerodynamic performance of circulation control airfoils

2021 ◽  
pp. 095441002098372
Author(s):  
Yu-Wei Chu ◽  
He-Yong Xu ◽  
Chen-Liang Qiao ◽  
Yu-Hang Wang ◽  
Yue Xu
Keyword(s):  
Lift Coefficient ◽  
Axial Ratio ◽  
Aerodynamic Performance ◽  
Careful Consideration ◽  
Circulation Control ◽  
Trailing Edge ◽  
Instability Phenomenon ◽  
Computational Evaluation ◽  
Coanda Jet ◽  
Geometric Effects

The geometric effects of Coanda trailing edges on the aerodynamic performance of an airfoil are numerically evaluated for a range of different freestream Mach numbers and momentum coefficients. A Circulation control (CC) airfoil with a circular trailing edge (ACTE) proves to have better control effectiveness at low subsonic freestream speeds (Mach = 0.1). A CC airfoil having an elliptic trailing edge (AETE) outperforms the ACTE at high subsonic flow conditions. The occurrence of C μ-stall for the AETE is greatly postponed, and meanwhile the maximum net lift coefficient increment achieved for the AETE (Δ C L = 0.51) is slightly higher than that of the ACTE (Δ C L = 0.50) at Mach 0.6. Compared to the ACTE, the AETE is found to have better control consistency at different operating velocities and better control stability when the Coanda jet is supersonic. Through careful consideration of the aerodynamic performance and the control effects, the most appropriate axial ratio for an AETE ellipse is within the interval from 1.5 to 2. Finally, the flow field instability phenomenon and the jet detachment induced by the supersonic Coanda jet are investigated. A self-sustained shock-wave instability phenomenon without jet detachment is first observed in this paper.

scholarly journals First principle analysis of Coandă Micro Air Vehicle aerodynamic forces for preliminary sizing

2017 ◽  
Vol 89 (2) ◽  
pp. 231-245
Author(s):  
Harijono Djojodihardjo ◽  
Riyadh Ibraheem Ahmed ◽  
Abd Rahim Abu Talib ◽  
Azmin Shakrine Mohd Rafie
Keyword(s):  
Mathematical Models ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Practical Interest ◽  
Micro Air Vehicle ◽  
Radius Of Curvature ◽  
Geometrical Parameters ◽  
Content Type ◽  
Air Vehicle ◽  
Coanda Jet

Purpose The purpose of this paper is to reformulate the governing equations incorporating major variables and parameters for the design a Micro Air Vehicle (MAV), to meet the desired mission and design requirements. Design/methodology/approach Mathematical models for various spherical and cylindrical Coandă MAV configurations were rederived from first principles, and the performance measures were defined. To verify the theoretical prediction to a certain extent, a computational fluid dynamic (CFD) simulation for a Coandă MAV generic models was performed. Findings The major variables and parameters of Coandă MAV have been formulated into practical guidelines, which relate the lift (or thrust) produced for certain input variables, particularly the Coandă MAV jet momentum coefficient. The influences of the geometrical parameters are elaborated. Research limitations/implications The present analysis on Coandă jet-configured MAV is focused on the lift generation due to the Coandă jet effect through a meticulous analysis. The effects of viscosity, the Coandă jet thickness, the radius of curvature of the surface and the stability of Coandă jet are not considered and will be the subject of the following work. Practical implications The results obtained can be used for sizing in the preliminary design of Coandă MAVs. Originality/value Physical and mathematical models were developed which can describe the physical phenomena of the flow field near the Coandă MAV surfaces influenced by Coandă jet sheets and for obtaining a relationship between relevant variables and parameters to the lift of practical interest.

Application of Coandă Jet for Generating Lift of Micro Air Vehicles - Preliminary Design Considerations

2014 ◽  
Vol 629 ◽  
pp. 139-144 ◽  
Author(s):  
Riyadh Ibraheem Ahmed ◽  
Harijono Djojodihardjo ◽  
A.B.D. Rahim bin Abu Talib ◽  
Mohd Faisal Abd Hamid
Keyword(s):  
Micro Air Vehicles ◽  
Coanda Effect ◽  
Preliminary Design ◽  
Circulation Control ◽  
Engineering Applications ◽  
Design Considerations ◽  
Coandǎ Effect ◽  
Coanda Jet ◽  
The Relationship ◽  
Air Vehicles

Coandă effect, which has been widely utilized in many engineering applications for circulation control, is here reviewed for the design of Coandă Micro-Air-Vehicles (MAVs). Based on the review, a basic spherical configuration is analyzed to obtain the relationship between relevant parameters to the lift that can be produced based on fundamental principles. The results can be used for preliminary design purposes and are discussed in view of existing literature.

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