Hysteresis of the Coanda Effect

For scientist, the Coanda effect has been an object of interest for a long time. All the time, some new applications of it are found although it has been more than a hundred years since Henri Coanda got a patent that was critical for that issue. Apart from aviation, it is more and more often used in ventilation systems to control the manner of air division and the design nozzles and ventilators. It is surprising, however, that a good command of that phenomenon and a need to apply it in different solutions did not entail a significant increase of the interest in the Coanda effect hysteresis, although it was mentioned for the first time by Newman in 1961. This article presents results of experimental measurements for a two-dimensional incompressible plane jet by an inclined plate. The hysteresis has been observed as a different jet behavior (a free jet or a jet attached to a flat plate) depending on the direction in which the plate deflection angle changes. The observed hysteresis area, defined by critical values for the αca attachment and αcd detachment angles, spanned from 8 deg to 14 deg. Its dependency on the Reynolds number has also been examined for Re ranging from 3500 to 26,500. Considering the Coanda effect hysteresis, a pressure distribution on the plate and the xR reattachment distance has been examined. The distribution of forces on a plate has been identified, which has facilitated a graphical mirroring of the Coanda effect hysteresis loop.

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PIV measurements and analysis of transitional flow in a reduced-scale model: Ventilation by a free plane jet with Coanda effect

Building and Environment ◽

10.1016/j.buildenv.2012.03.020 ◽

2012 ◽

Vol 56 ◽

pp. 301-313 ◽

Cited By ~ 34

Author(s):

T. van Hooff ◽

B. Blocken ◽

T. Defraeye ◽

J. Carmeliet ◽

G.J.F. van Heijst

Keyword(s):

Transitional Flow ◽

Scale Model ◽

Coanda Effect ◽

Piv Measurements ◽

Coandǎ Effect ◽

Plane Jet ◽

Free Plane ◽

Reduced Scale

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Pressure Distribution On A Flat Plate In The Context of The Phenomenon of The Coanda Effect Hysteresis

10.21203/rs.3.rs-1054725/v1 ◽

2021 ◽

Author(s):

Aldona Skotnicka-Siepsiak

Keyword(s):

Pressure Distribution ◽

Flat Plate ◽

Experimental Research ◽

Coanda Effect ◽

Wall Jet ◽

Plate Surface ◽

Initial Angle ◽

Free Jet ◽

Pressure Distributions ◽

Coandǎ Effect

Abstract As a result of the Coanda effect, a symmetrical free jet will flow as an asymmetrical wall jet. At the same time, at the obstacle along which the flow is observed, the wall jet generates pressure distribution. In this study, the obstacle located at the diffuser outlet is a flat plate with a variable inclination angle. The article presents results of the study on pressure distributions on a flat plate with a variable angle of inclination. What is new, however, is that the presented results of the experimental research include the influence of the Coanda effect hysteresis on the pressure distribution on the plate. The article shows how pressure distributions change on the plate depending on whether the initial angle of inclination was 0 degree and was increased gradually in the course of the experiment until a detachment of the jet flowing from the plate was observed, or the initial angle of inclination was close to 90 degrees in the primal state and as the angle of the plate inclination was decreased, the jet flowing towards the plate reached the state of attachment to the plate surface.

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Theoretical and practical aspects of the Coandă effect applied in aeronautics

MATEC Web of Conferences ◽

10.1051/matecconf/201929006003 ◽

2019 ◽

Vol 290 ◽

pp. 06003

Author(s):

Ionică Cîrciu ◽

Constantin Rotaru

Keyword(s):

Flue Gas ◽

Convex Surface ◽

Dynamic Effect ◽

Coanda Effect ◽

Gas Jets ◽

Fluid Jets ◽

Coandǎ Effect ◽

First Time ◽

Airplane Fuselage ◽

Short Flight

The Coandă Effect, or better said, the deviation of fluid jets to stay attached to a convex surface is a complex gas-dynamic effect, named after the Romanian aviation engineer Henri Coandă and it was for the first time highlighted by him in 1910 during the take-off of one of his first planes, Coandă-1910, which was also the first jet plane to fly. During the short flight, Coandă was able to notice the near-fit alignment of the flue gas jets with the airplane fuselage. Later, both Coandă and other scholars have intensively studied the effect that is named The Coandă Effect, in his honor.

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Flow of a falling liquid curtain into a pool

Journal of Fluid Mechanics ◽

10.1017/jfm.2013.672 ◽

2014 ◽

Vol 741 ◽

pp. 350-376 ◽

Cited By ~ 2

Author(s):

Harumichi Kyotoh ◽

Kazuki Fujita ◽

Koichi Nakano ◽

Takeaki Tsuda

Keyword(s):

Deflection Angle ◽

Coanda Effect ◽

Vertical Flow ◽

Pool Surface ◽

Oblique Flow ◽

Conservation Of Momentum ◽

Number Flow ◽

The Deflection Angle ◽

Simulation Results ◽

Coandǎ Effect

AbstractWe investigate the low-Weber-number flow of a liquid curtain bridged between two vertical edge guides and a pool surface. Three flow patterns, namely, steady vertical flow, steady oblique flow, and oscillatory oblique flow, are observed in our experiment. These patterns are caused by the Coanda effect of the jet around the meniscus that is formed in the matching region common to the liquid curtain and the pool surface. Here, the deflection angle of the jet is greater than $90^\circ $. The equation describing the motion of the liquid curtain applicable for a finite curtain slope is obtained using the intrinsic coordinate system in which the distance along the curtain is selected as one of the coordinates, and the equation of the meniscus motion is derived by considering the conservation of momentum. The curtain deformations of oblique flows are analysed by generating numerical simulations of these equations, and the simulation results are then compared with experimental results. Also, the period of oscillatory oblique flow is discussed and explained via the response analyses of the curtain, and the result shows that the period of the oscillations is close to that of the most amplified mode of the liquid curtain. Further, the detachment angle of the jet is discussed in relation to the Coanda effect of the jet in the meniscus.

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Direct imaging of charge transfer

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100165860 ◽

1996 ◽

Vol 54 ◽

pp. 680-681

Author(s):

Yimei Zhu ◽

J. Tafto

Keyword(s):

Charge Transfer ◽

Electron Diffraction ◽

Scattering Amplitude ◽

High Temperature Superconductors ◽

Charge Carriers ◽

Image Charge ◽

Net Charge ◽

Long Time ◽

Electron Holes ◽

First Time

The electron holes confined to the CuO2-plane are the charge carriers in high-temperature superconductors, and thus, the distribution of charge plays a key role in determining their superconducting properties. While it has been known for a long time that in principle, electron diffraction at low angles is very sensitive to charge transfer, we, for the first time, show that under a proper TEM imaging condition, it is possible to directly image charge in crystals with a large unit cell. We apply this new way of studying charge distribution to the technologically important Bi2Sr2Ca1Cu2O8+δ superconductors.Charged particles interact with the electrostatic potential, and thus, for small scattering angles, the incident particle sees a nuclei that is screened by the electron cloud. Hence, the scattering amplitude mainly is determined by the net charge of the ion. Comparing with the high Z neutral Bi atom, we note that the scattering amplitude of the hole or an electron is larger at small scattering angles. This is in stark contrast to the displacements which contribute negligibly to the electron diffraction pattern at small angles because of the short g-vectors.

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COANDA EFFECT

A-to-Z Guide to Thermodynamics Heat and Mass Transfer and Fluids Engineering ◽

10.1615/atoz.c.coaeff ◽

2006 ◽

Vol c ◽

Author(s):

C. Swan

Keyword(s):

Coanda Effect ◽

Coandǎ Effect

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Assessment of recreational use of specially protected natural territories of Tatishchevsky district of Saratov region

RUDN Journal of Ecology and Life Safety ◽

10.22363/2313-2310-2019-27-2-117-127 ◽

2019 ◽

Vol 27 (2) ◽

pp. 117-127

Author(s):

Yulia M Andriyanova ◽

Irina V Sergeeva ◽

Yulia M Mokhonko ◽

Natalia N Gusakova

Keyword(s):

Natural Resources ◽

Protected Areas ◽

Saratov Region ◽

Future State ◽

Forest Phytocenoses ◽

Long Time ◽

Main Components ◽

First Time ◽

Recreational Use ◽

Specially Protected Natural Territories

The influence of recreation being a set of measures to restore health and recreation, on the main components of forest phytocenoses in specially protected natural territories of the Tatishchevsky district of the Saratov region has been studied for the first time. These phytocenoses have been intensively used for tourism for a long time. The intensity and visits activity of protected areas has been determined; the recreational capacity of territorial objects has been studied. The degree of forest landscapes has been revealed in specially protected natural territories. The findings allow predicting the future state of the natural resources of the Saratov region and can be taken into account when assessing their optimal use.

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Clinical significance of late diastolic tissue doppler parameters after onset of STEMI: from the view point of the timing of the echocardipography

European Heart Journal ◽

10.1093/ehjci/ehaa946.0074 ◽

2020 ◽

Vol 41 (Supplement_2) ◽

Author(s):

N Iwahashi ◽

J Kirigaya ◽

M Horii ◽

T Abe ◽

E Akiyama ◽

...

Keyword(s):

Tissue Doppler ◽

Atrial Function ◽

Diastolic Velocity ◽

Long Time ◽

Group A ◽

St Elevation ◽

Group B ◽

First Time

Abstract Background The early transmitral flow velocity (E) divided by the early diastolic velocity of the mitral valve annulus (e') is referred to as the “E/e' ratio,” is useful even for ST elevation acute myocardial infarction (STEMI). However, the role of late diastolic velocity (a') which reveals the atrial function for STEMI is still unclear. Objectives We evaluated the clinical usefulness of tissue Doppler including atrial function for a first-time STEMI by long time follow up. Furthermore, we evaluated the meaning of each parameters by performing immediately after PCI or 2 weeks later. Methods We treated consecutive 571 first-time STEMI patients by immediate PCI within 12 hours after onset, and we examined 270 patients at immediately after PCI (GroupA, 65 years, 250 male) and 301 patients at 2 weeks after onset (GroupB, 64 years, 243 male). We examined trans mitral flow and TDI, then defined E/e' as LV filling pressure and A/a' as left atrial function. We followed them for a long time (>5 years). The primary end point (PE) was cardiac death or re-admission for heart failure (HF). Results We followed the patients in Group A for 10 years, Group B for 5 years. PE occurred in 64 patients in GroupA during 10 years, and 45 patients in GroupB during 5 years. We analyzed the univariate and multivariate Cox hazard analyses and we compared e' and a', E/e' and A/a' (Table). In GroupA, a' and A/a' were the independent predictors, on the other hand neither a' nor A/a' were the predictors in GroupB. E/e' was an independent predictor both in GroupA and B. Conclusion TDI parameters have different meanings by the timing of echocardiography after onset of a first-time STEMI. These results demonstrated that atrial dysfunction immediately after onset of STEMI suggests the poor prognosis after STEMI. Cox Hazard Proportional Analysis Funding Acknowledgement Type of funding source: None

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