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Tuesday, August 4, 2020 | History

3 edition of Turbulence characteristics of swirling flowfields found in the catalog.

Turbulence characteristics of swirling flowfields

Turbulence characteristics of swirling flowfields

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  • 23 Currently reading

Published by National Aeronautics and Space Administration in [Washington, D.C.? .
Written in English

    Subjects:
  • Turbulence.,
  • Aerodynamics.

  • Edition Notes

    Statementby Trevor William Jackson.
    SeriesNASA-CR -- 175392., NASA contractor report -- NASA CR-175392.
    ContributionsOklahoma State University., United States. National Aeronautics and Space Administration.
    The Physical Object
    FormatMicroform
    Pagination1 v.
    ID Numbers
    Open LibraryOL17666181M

    Characteristics of Turbulent Flow. Turbulent flow tends to occur at higher velocities, low viscosity and at higher characteristic linear dimensions.; If the Reynolds number is greater than Re > , the flow is turbulent. Irregularity: The flow is characterized by the irregular movement of particles of the fluid. The movement of fluid particles is chaotic.   The interaction between the coaxial air microjet structure and the swirling flow is investigated numerically based on the nonpremixed bluff-body stabilized swirling SM1 flame. The effects of microjet velocity and swirl number on flame combustion characteristics are analyzed. The modified standard k–ε model and the realizable k–ε model are considered for the turbulent model using .

      Swirling strength is an effective vortex indicator in wall turbulence, and it can be determined based on either two-dimensional (2D) or three-dimensional (3D) velocity fields, written as λ ci2D and λ ci3D, respectively.A comparison between λ ci2D and λ ci3D has been made in this paper in sliced XY, YZ, and XZ planes by using 3D DNS data of channel flow. Two separate flowfields were investigated: a round, swirling jet and a non-combusting annular combustor model. These studies were intended to allow both a further understanding of the behavior of general swirling flow characteristics, such as the recirculation zone, as well as to provide a base for the development of computational models.

      Turbulence is the way air fuel mixture moves inside a combustion chamber. If the turbulence of charge is more, then the air and fuel moves randomly inside the chamber. Swirl is a turbulent motion of air fuel mixture, which is obtained from different piston head design, combustion chamber types and air fuel injection methods. Turbulent flow in slightly heated free swirling jets E u: = y+ 10 w FIGURE 3. (a) Flow characteristics at the exit plane of unswirled jet Bave = 40": 0, Tz/Dave; 0, s/gave; A, $/Pave x 10; a, p/73Eve x (a) Mean-velocity profile in the exit boundary layer: gave = 40°, x/D = 0, 0. i 10 1 w 10 I ' YP 1 0 FIGURE 4.(a) Flow characteristics at the exit plane of swirlinq.


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Turbulence characteristics of swirling flowfields Download PDF EPUB FB2

Get this from a library. Turbulence characteristics of swirling flowfields. [Trevor William Jackson; Oklahoma State University.; United States. National Aeronautics and Space Administration.].

COVID Resources. Reliable information about the coronavirus (COVID) is available from the World Health Turbulence characteristics of swirling flowfields book (current situation, international travel).Numerous and frequently-updated resource results are available from this ’s WebJunction has pulled together information and resources to assist library staff as they consider how to handle coronavirus.

Turbulence characteristics of swirling flowfields. By T. Jackson and D. Lilley. Abstract. The time mean and turbulence properties of a confined swirling jet using the six orientation, single hot wire technique were obtained. The effect of swirl on a confined, expanding jet is to reduce the size of the corner recirculation zone and Author: T.

Jackson and D. Lilley. Using particle image velocimetry, the nonreacting and reacting flowfields were measured at five bulk flow velocities. The results show that the LSI flowfield exhibits similarity features. From the velocity data, an analytical expression for the flame position as function of the flowfield characteristics and turbulent flame speed has been by: Turbulence Characteristics of Swirling Flowfields.

By T. Jackson. Abstract. Combustor design phenomena; recirculating flows research; single-wire, six-orientation, eddy dissipation rate, and turbulence modeling measurement; directional sensitivity (DS); calibration equipment, confined jet facility, and hot-wire instrumentation; effects of Author: T.

Jackson. Due to the presence of swirling motions in the STVC, significant 3-D flows are introduced into the cavity vortex, and vortex breakdown is established in the sudden expansion region of the combustor. Furthermore, turbulence levels (i.e. turbulence kinetic energy and turbulence intensity) are found to be increased significantly by approximately %.

Characteristics of swirling flow generated by simple swirlers have been reviewed and investigated by multiple researchers. These reviews have provided different methods of generating swirl in the system, the parameters that affect the size of the recirculation zone, and flow structure produced by different swirlers.

A Comparison of the Flowfields and Emissions of High-Swirl Injectors and Low-Swirl Injectors for Lean Premixed Gas Turbines,” Laboratory Studies of the Flow Field Characteristics of Low-Swirl Injectors for Application to Fuel-Flexible Turbines,” The Burning Rate of Premixed Flames in Moderate and Intense Turbulence,” Combust.

Flame. A simple, yet representative, burner geometry is used for the investigation of highly swirling turbulent unconfined, non-premixed, flames of natural gas.

The burner configuration comprises a ceramic faced bluff-body with a central fuel jet. The bluff-body is surrounded by an annulus that delivers a swirling primary flow of air. Effect of swirl on the turbulent behaviour of a dump combustor flow 17 December | Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Vol.No.

Turbulence Characteristics of Swirling Reacting Flow in a Combustor with Staged Air Injection Chinese Journal of Chemical Engineering, Vol. 14, No. 5 SWIRLING JET SYSTEMS FOR COMBUSTION CONTROL Effect of exhaust nozzle geometry on combustor flow field and combustion characteristics. CiteSeerX - Document Details (Isaac Councill, Lee Giles, Pradeep Teregowda): A two-component fibre-optic laser Doppler velocimeter (LDV) system has been employed to measure the flowfield characteristics of a confined, isothermal strongly swirling flow in a combustor model.

The primary objectives are to understand such complex flowfields and to provide complete benchmark data for. The degree of swirl of the flow generally has a strong effect on the formation of turbulence in the flow, which in turn characterizes the region of mixing of co-axial swirl flows.

The present work. The presented measurements include: highly swirling flows inside and downstream of advanced engine swirl cups and primary zone flowfields.

The swirling flow measurements were made inside a X3 model of an advanced swirl cup featuring two co-axial swirling streams. By using both conventional particle image velocimetry (PIV) and high-speed dynamic PIV, the statistical characteristics of elastic turbulence in a free-surface swirling flow were studied.

Flow patterns of the elastic turbulence were observed in the PIV-measured velocity fields in both lateral and meridional planes for CTAC (cetyltrimethyl ammonium chloride) solution flows at low Reynolds numbers.

One possible method of combining the measurement data is introduced and discussed with application to swirling flowfields which exhibit a precessing vortex core.

The analysis indicates that in such flows the unsteadiness accounts for up to 70% of the total energy in the velocity fluctuations.

Turbulence, In fluid mechanics, a flow condition (see turbulent flow) in which local speed and pressure change unpredictably as an average flow is maintained. Common examples are wind and water swirling around obstructions, or fast flow (Reynolds number greater than 2,) of any sort.

Swirl vanes play a role diffusing main flow more remarkably toward the radial direction than axial one, but slits show a reverse feature. Consequently, both slits and swirl vanes remarkably increase turbulence intensity in the whole range of a gun-type gas burner with a cone-type baffle plate.

Acquainting oneself with this book should be a thoroughly enjoyable and enriching experience. Indeed a welcome and distinct addition to the literature on turbulence. It will serve well as an impressive textbook admirably making up for the dearth of material on turbulence modelling.’ Source: Current Engineering Practice.

The paper presents an assessment of the performances of RANS turbulence models for simulating turbulent swirling can-combustor flows with different inlet swirl intensities (i.e. S= and S=). Turbulence was firstly modelled and validated against experimental results from the ERCOFTAC swirling conical diffuser database and previous numerical results.

The real gas thermodynamic and transport properties of refrigerant Ra were then obtained from the NIST REFPROP database.Turbulent flow, type of fluid (gas or liquid) flow in which the fluid undergoes irregular fluctuations, or mixing, in contrast to laminar flow, in which the fluid moves in smooth paths or layers.

In turbulent flow the speed of the fluid at a point is continuously undergoing changes in both magnitude and direction.Swirling flames with varying departures from blow-off have recently been studied using a simple, yet representative swirl burner.

Extensive measurements of flow, stability and composition fields have already been made in turbulent non-premixed swirling flames covering a range of fuel mixtures and swirl numbers. The data, which are now made available on the World Wide Web, have revealed complex.