scholarly journals VII. An investigation of the air-flow pattern in the wake of an aërofoil of finite span

1926 ◽  
Vol 225 (626-635) ◽  
pp. 303-330 ◽  
Keyword(s):  
Wind Speed ◽  
Flow Pattern ◽  
Direct Measurement ◽  
Opposite Direction ◽  
Air Flow ◽  
Point Of View ◽  
Complete Picture ◽  
Finite Span ◽  
Theoretical Considerations ◽  
Circulatory Motion

1. The earliest physical conception of the flow in the wake of an advancing aërofoil of finite span was suggested by Lanchester, who showed, from theoretical considerations, that it should comprise a layer of vorticity immediately behind the trailing edge and two general circulatory motions of opposite direction of rotation, one at each aērofoil tip. Since that time, photographs of this circulatory motion of air at the aërofoil tips have been taken by Caldwell and Fales, and other experimenters have located, by direct measurement, regions of vorticity in the wake, principally behind the aërofoil tips. The purpose of the present investigation is to obtain, by precise measurements of the wind speed and direction, a more complete picture than has hitherto been available of the disturbance behind an aërofoil of finite span, and to map out the changes which occur in the extent and distribution of the vorticity in the wake as it passes down-stream. The measured vorticity is considered in relation to the circulation around the aërofoil, and from this point of view the work herein described may be regarded as a continuation of that undertaken by L. W. Bryant and D. H. Williams,|| who confirmed experimentally the Kutta-Joukowsky relation connecting circulation and lift.

scholarly journals A Reliability Based Model for Wind Turbine Selection

2013 ◽  
Vol 2 (2) ◽  
pp. 69-74 ◽  
Author(s):  
A.K. Rajeevan ◽  
P.V. Shouri ◽  
Usha Nair
Keyword(s):  
Power Generation ◽  
Wind Speed ◽  
Wind Turbine ◽  
Wind Power ◽  
Point Of View ◽  
Cube Root ◽  
Mathematical Relationship ◽  
Turbine Generator ◽  
Wind Turbine Generator ◽  
A Site

A wind turbine generator output at a specific site depends on many factors, particularly cut- in, rated and cut-out wind speed parameters. Hence power output varies from turbine to turbine. The objective of this paper is to develop a mathematical relationship between reliability and wind power generation. The analytical computation of monthly wind power is obtained from weibull statistical model using cubic mean cube root of wind speed. Reliability calculation is based on failure probability analysis. There are many different types of wind turbinescommercially available in the market. From reliability point of view, to get optimum reliability in power generation, it is desirable to select a wind turbine generator which is best suited for a site. The mathematical relationship developed in this paper can be used for site-matching turbine selection in reliability point of view.

The Impact of Urbanization on Air Flow Pattern: The Case of Rio de Janeiro

2014 ◽  
Vol 12 (9) ◽  
pp. 908-916 ◽  
Author(s):  
Marilia Ramalho Fontenelle ◽  
Sylvie Lorente ◽  
Leopoldo Eurico Gonçalves Bastos
Keyword(s):  
Flow Pattern ◽  
Rio De Janeiro ◽  
Air Flow ◽  
Impact Of Urbanization ◽  
The Impact

Natural-Ventilation Flow in a 3-D Room Fitted With Solar Chimney

2012 ◽  
Author(s):  
B. P. Huynh
Keyword(s):  
Heat Flux ◽  
Flow Pattern ◽  
Natural Ventilation ◽  
Air Flow ◽  
Ventilation Rate ◽  
High Heat Flux ◽  
Solar Chimney ◽  
Solar Heat ◽  
Solar Heat Flux ◽  
Inlet Opening

Natural-ventilation flow induced in a real-sized rectangular-box room fitted with a solar chimney on its roof is investigated numerically, using a commercial CFD (Computational Fluid Dynamics) software package. The chimney in turn is in the form of a parallel channel with one plate being subjected to uniform solar heat flux. Ventilation rate and air-flow pattern through the room are considered in terms of the heat flux for two different locations of the room’s inlet opening. Chien’s turbulence model of low-Reynolds-number K-ε is used in a Reynolds-Averaged Navier-Stokes (RANS) formulation. It is found that ventilation flow rate increases quickly with solar heat flux when this flux is low, but more gradually at higher flux. At low heat flux, ventilation rate is not significantly affected by location of the inlet opening to the room. On the other hand, at high heat flux, ventilation rate varies substantially with the opening’s location. Location of the inlet opening to the room also affects strongly the air-flow pattern. In any case, ample ventilation rate is readily induced by the chimney.

scholarly journals Research Active Posterior Rhinomanometry Tomography Method for Nasal Breathing Determining Violations

Sensors ◽  
2021 ◽  
Vol 21 (24) ◽  
pp. 8508
Author(s):  
Oleg G. Avrunin ◽  
Yana V. Nosova ◽  
Ibrahim Younouss Abdelhamid ◽  
Sergii V. Pavlov ◽  
Natalia O. Shushliapina ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Pressure Drop ◽  
Flow Rate ◽  
Dynamic Change ◽  
Air Flow ◽  
Current Mode ◽  
Forced Response ◽  
Point Of View ◽  
Air Flow Rate ◽  
Nasal Breathing

This study analyzes the existing methods for studying nasal breathing. The aspects of verifying the results of rhinomanometric diagnostics according to the data of spiral computed tomography are considered, and the methodological features of dynamic posterior active rhinomanometry and the main indicators of respiration are also analyzed. The possibilities of testing respiratory olfactory disorders are considered, the analysis of errors in rhinomanometric measurements is carried out. In the conclusions, practical recommendations are given that have been developed for the design and operation of tools for functional diagnostics of nasal breathing disorders. It is advisable, according to the data of dynamic rhinomanometry, to assess the functioning of the nasal valve by the shape of the air flow rate signals during forced breathing and the structures of the soft palate by the residual nasopharyngeal pressure drop. It is imperative to take into account not only the maximum coefficient of aerodynamic nose drag, but also the values of the pressure drop and air flow rate in the area of transition to the turbulent quadratic flow regime. From the point of view of the physiology of the nasal response, it is necessary to look at the dynamic change to the current mode, given the hour of the forced response, so that it will ensure the maximum possible acidity in the legend. When planning functional rhinosurgical operations, it is necessary to apply the calculation method using computed tomography, which makes it possible to predict the functional result of surgery.

The Simulation of Natural Ventilation of Buildings With Different Location of Windows/Openings

2015 ◽  
Author(s):  
A. Idris ◽  
B. P. Huynh ◽  
Z. Abdullah
Keyword(s):  
Air Quality ◽  
Flow Pattern ◽  
Turbulence Model ◽  
Natural Ventilation ◽  
Air Flow ◽  
Building Design ◽  
Building Envelope ◽  
Navier Stokes ◽  
Computational Domain ◽  
Numerical Predictions

Ventilation is a process of changing air in an enclosed space. Air should continuously be withdrawn and replaced by fresh air from a clean external source to maintain internal good air quality, which may referred to air quality within and around the building structures. In natural ventilation the air flow is due through cracks in the building envelope or purposely installed openings. Its can save significant amount of fossil fuel based energy by reducing the needs for mechanical ventilation and air conditioning. Numerical predictions of air velocities and the flow patterns inside the building are determined. To achieve optimum efficiency of natural ventilation, the building design should start from the climatic conditions and orography of the construction to ensure the building permeability to the outside airflow to absorb heat from indoors to reduce temperatures. Effective ventilation in a building will affects the occupant health and productivity. In this work, computational simulation is performed on a real-sized box-room with dimensions 5 m × 5 m × 5 m. Single-sided ventilation is considered whereby openings are located only on the same wall. Two opening of the total area 4 m2 are differently arranged, resulting in 16 configurations to be investigated. A logarithmic wind profile upwind of the building is employed. A commercial Computational Fluid Dynamics (CFD) software package CFD-ACE of ESI group is used. A Reynolds Average Navier Stokes (RANS) turbulence model & LES turbulence model are used to predict the air’s flow rate and air flow pattern. The governing equations for large eddy motion were obtained by filtering the Navier-Stokes and continuity equations. The computational domain was constructed had a height of 4H, width of 9H and length of 13H (H=5m), sufficiently large to avoid disturbance of air flow around the building. From the overall results, the lowest and the highest ventilation rates were obtained with windward opening and leeward opening respectively. The location and arrangement of opening affects ventilation and air flow pattern.

scholarly journals Enzyme catalysis as a chain reaction

1991 ◽  
Vol 279 (3) ◽  
pp. 855-861 ◽  
Author(s):  
S E Szedlacsek ◽  
R G Duggleby ◽  
M O Vlad
Keyword(s):  
Reaction Mechanism ◽  
Kinetic Mechanism ◽  
Point Of View ◽  
Simple Type ◽  
Chain Reaction ◽  
Proposed Model ◽  
New Type ◽  
A Chain ◽  
Theoretical Considerations ◽  
Classical Mechanism

A new type of enzyme kinetic mechanism is suggested by which catalysis may be viewed as a chain reaction. A simple type of one-substrate/one-product reaction mechanism has been analysed from this point of view, and the kinetics, in both the transient and the steady-state phases, has been reconsidered. This analysis, as well as literature data and theoretical considerations, shows that the proposed model is a generalization of the classical ones. As a consequence of the suggested mechanism, the expressions, and in some cases even the significance of classical constants (Km and Vmax.), are altered. Moreover, this mechanism suggests that, between two successive enzyme-binding steps, more than one catalytic act could be accomplished. The reaction catalysed by alcohol dehydrogenase was analysed, and it was shown that this chain-reaction mechanism has a real contribution to the catalytic process, which could become exclusive under particular conditions. Similarly, the mechanism of glycogen phosphorylase is considered, and two partly modified versions of the classical mechanism are proposed. They account for both the existing experimental facts and suggest the possibility of chain-reaction pathways for any polymerase.

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