Coupled and Uncoupled CFD Prediction of the Characteristics of Jets From Combustor Air Admission Ports

2000 ◽  
Author(s):  
J. J. McGuirk ◽  
A. Spencer
Keyword(s):  
Internal Flow ◽  
Flow Conditions ◽  
Empirical Correlations ◽  
Weakly Coupled ◽  
Primary Zone ◽  
Annular Combustor ◽  
Alternative Approaches ◽  
Jet Characteristics ◽  
Fully Coupled ◽  
Core Flows

The paper focusses attention on alternative approaches for treating the coupling between the flow in the annulus supply ducts and the jets which enter combustor primary and dilution zones through air admission ports. Traditionally CFD predictions of combustor flows have modeled this in a very weakly-coupled manner, with the port flow conditions being derived from 1D empirical correlations and used as boundary conditions for an internal-flow-only combustor CFD prediction. Recent work by the authors and others has introduced the viewpoint that fully-coupled external-annulus/internal-combustor predictions is the way forward. Experimental data is gathered in the present work to quantify the strength of the interaction between annulus and core flows, which ultimately determines the jet characteristics at port exit. These data are then used to illustrate the improvement in the prediction of port exit jet characteristics which is obtained by adopting fully-coupled calculations compared to the internal-flow-only approach. As a final demonstration of the importance of a fully coupled approach, isothermal calculations are presented for a single sector generic annular combustor. These show that quite different primary zone flow patterns are obtained from the two approaches, leading to considerable differences in the overall mixing pattern at combustor exit.

Coupled and Uncoupled CFD Prediction of the Characteristics of Jets From Combustor Air Admission Ports

2001 ◽  
Vol 123 (2) ◽  
pp. 327-332 ◽  
Author(s):  
J. J. McGuirk ◽  
A. Spencer
Keyword(s):  
Internal Flow ◽  
Flow Conditions ◽  
Empirical Correlations ◽  
Weakly Coupled ◽  
Primary Zone ◽  
Annular Combustor ◽  
Alternative Approaches ◽  
Jet Characteristics ◽  
Fully Coupled ◽  
Core Flows

The paper focusses attention on alternative approaches for treating the coupling between the flow in the annulus supply ducts and the jets which enter combustor primary and dilution zones through air admission ports. Traditionally CFD predictions of combustor flows have modeled this in a very weakly coupled manner, with the port flow conditions being derived from 1D empirical correlations and used as boundary conditions for an internal-flow-only combustor CFD prediction. Recent work by the authors and others has introduced the viewpoint that fully coupled external-annulus–internal-combustor predictions is the way forward. Experimental data is gathered in the present work to quantify the strength of the interaction between annulus and core flows, which ultimately determines the jet characteristics at port exit. These data are then used to illustrate the improvement in the prediction of port exit jet characteristics which is obtained by adopting fully coupled calculations compared to the internal-flow-only approach. As a final demonstration of the importance of a fully coupled approach, isothermal calculations are presented for a single sector generic annular combustor. These show that quite different primary zone flow patterns are obtained from the two approaches, leading to considerable differences in the overall mixing pattern at combustor exit.

Improvement of Stalling Characteristics of an Axial-Flow Fan by Radial-Vaned Air-Separators

2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Nobuyuki Yamaguchi ◽  
Masayuki Ogata ◽  
Yohei Kato
Keyword(s):  
Solid Wall ◽  
Axial Flow ◽  
Internal Flow ◽  
Rotor Blades ◽  
Relative Location ◽  
Flow Conditions ◽  
Axial Flow Fan ◽  
Light Load ◽  
Stall Prevention ◽  
Air Separator

An improved construction of air-separator device, which has radial-vanes embedded within its inlet circumferential opening with their leading-edges facing the moving tips of the fan rotor-blades so as to scoop the tip flow, was investigated with respect to the stall-prevention effect on a low-speed, single-stage, lightly loaded, axial-flow fan. Stall-prevention effects by the separator layout, relative location of the separator to the rotor-blades, and widths of the openings of the air-separator inlet and exit were parametrically surveyed. As far as the particular fan is concerned, the device together with the best relative location has proved to be able to eliminate effectively the stall zone having existed in the original solid-wall characteristics, which has confirmed the promising potential of the device. Guidelines were obtained from the data for optimizing relative locations of the device to the rotor-blades, maximizing the stall-prevention effect of the device, and minimizing the axial size of the device for a required stall-prevention effect, at least for the particular fan and possibly for fans of similar light-load fans. The data suggest the changing internal flow conditions affected by the device conditions.

Calculation of the Flow in a Sector of an Annular Combustor

1989 ◽  
Vol 203 (3) ◽  
pp. 187-193 ◽  
Author(s):  
W P Jones ◽  
M N Sodha ◽  
J J McGuirk
Keyword(s):  
Gas Turbines ◽  
Piecewise Linear ◽  
Turbulent Transport ◽  
Physical Domain ◽  
Measured Velocity ◽  
Acceptable Accuracy ◽  
Primary Zone ◽  
Domain Boundaries ◽  
Annular Combustor ◽  
Measured Flow

Calculations have been made of the isothermal flow field within a sector of an annular combustion chamber representative of the type to be found in small gas turbines. The complex combustor geometry is described using a Cartesian finite difference mesh within which the physical domain boundaries are represented in a piecewise linear fashion. The k-s turbulence model is used to describe turbulent transport. Overall the calculated and measured flow fields are found to be in reasonable agreement and in the primary zone measured velocity profiles are reproduced to within an acceptable accuracy.

Linear thermoelasticity

2020 ◽  
pp. 257-285
Author(s):  
Lallit Anand ◽  
Sanjay Govindjee
Keyword(s):  
Linear Theory ◽  
Mechanical Response ◽  
Thermal Response ◽  
Engineering Applications ◽  
Temperature Changes ◽  
Weakly Coupled ◽  
Linear Thermoelasticity ◽  
Basic Equations ◽  
Fully Coupled ◽  
Coupled Theory

This chapter presents a theory for the coupled thermal and mechanical response of solids under circumstances in which the deformations are small and elastic, and the temperature changes from a reference temperature are small --- a framework known as the theory of linear thermoelasticity. The basic equations of the fully-coupled linear theory of anisotropic thermoelasticity are derived. These equations are then specialized for the case of isotropic materials. Finally, as a further specialization a weakly-coupled theory in which the temperature affects the mechanical response, but the deformation does not affect the thermal response, are discussed; this is a specialization which is of importance for many engineering applications, a few of which are illustrated in the examples.

scholarly journals Design of Pressurized Metered Dose Inhalers Modeling of Internal Flow and Atomization

2010 ◽  
Vol 4 (2) ◽  
Author(s):  
Henk Versteeg ◽  
Abdul Qaiyum Shaik
Keyword(s):  
Experimental Work ◽  
Equilibrium Model ◽  
Lung Diseases ◽  
Internal Flow ◽  
Flow Conditions ◽  
Metered Dose Inhalers ◽  
Numerical Predictions ◽  
Metered Dose ◽  
Flow Through ◽  
Pressurized Metered Dose Inhalers

Pressurized metered-dose inhalers (pMDIs) have been the most effective therapeutic treatment for controlling lung diseases such as asthma and COPD. The flow through a two-orifice system of pMDI is very complex and poorly understood. Previous experimental work has shown that metastability may play a significant role in determining the flow conditions inside pMDIs. In this paper, we present the findings of a homogeneous equilibrium model with those of a delayed equilibrium model (DEM) accounting for propellant metastability. These results are compared with the available experimental and numerical predictions Further, the DEM was applied with HFA propellants R134A and R227, and the results were compared with traditional propellant R12.

scholarly journals Experimental Investigation of an Atmospheric Rectangular Rich Quench Lean Combustor Sector for Aeroengines

1997 ◽  
Author(s):  
Peter Griebel ◽  
Michael Fischer ◽  
Christoph Hassa ◽  
Eggert Magens ◽  
Henning Nannen ◽  
...  
Keyword(s):  
Research Work ◽  
Nox Formation ◽  
Lean Combustion ◽  
Air Jets ◽  
Primary Zone ◽  
Low Emission ◽  
Measuring Techniques ◽  
Annular Combustor ◽  
High Turbulence ◽  
Secondary Air

In this research work the potential of rich quench lean combustion for low emission aeroengines is investigated in a rectangular atmospheric sector, representing a segment of an annular combustor. For a constant design point (cruise) the mixing process and the NOx formation are studied in detail by concentration, temperature and velocity measurements using intrusive and non-intrusive measuring techniques. Measurements at the exit of the homogeneous primary zone show relatively high levels of non-thermal NO. The NOx formation in the quench zone is very low due to the quick mixing of the secondary air achieved by an adequate penetration of the secondary air jets and a high turbulence level. The NOx and CO emissions at the combustor exit are low and the pattern factor of the temperature distribution is sufficient.

Unsteady internal flow conditions of mini-centrifugal pump with splitter blades

2013 ◽  
Vol 22 (1) ◽  
pp. 86-91 ◽  
Author(s):  
T. Shigemitsu ◽  
J. Fukutomi ◽  
K. Kaji ◽  
T. Wada
Keyword(s):  
Centrifugal Pump ◽  
Internal Flow ◽  
Flow Conditions

Impact of Thermophoresis on Carbon Nanotube Growth by Chemical Vapor Deposition

2008 ◽  
Author(s):  
Andrew C. Lysaght ◽  
Wilson K. S. Chiu
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Scale Model ◽  
Reactor Wall ◽  
Flow Conditions ◽  
Energy Equations ◽  
Carbon Nanotube Growth ◽  
Nanotube Growth ◽  
Fully Coupled

Thermophoretic effect on the growth of carbon nanotubes (CNTs) by chemical vapor deposition (CVD) has been investigated using a fully coupled gas-phase and surface chemistry model. This reactor-scale model employs conservation of mass, momentum, species, and energy equations to describe the evolution of hydrogen and hydrocarbon feed streams as they undergo thermal transport and chemical reactions within the CVD reactor. The resulting CNT growth rates on individual catalytic iron nanoparticles located on the reactor wall is predicted by the model as well as steady state velocity, temperature, and concentration fields within the reactor volume and concentrations of species adsorbed onto the nanoparticle surfaces. The effect of thermophoresis on volumetric concentration fields and surface species adsorption for deposition occurring in differing reactor boundary and flow conditions has been investigated to understand the impacts on CNT growth. This investigation is useful in order to optimize reactor design and boundary conditions to promote optimal CNT deposition rates.

Internal flow and external jet characteristics of double serpentine nozzle with different aspect ratio

2017 ◽  
Vol 233 (2) ◽  
pp. 545-560 ◽  
Author(s):  
Sun Xiao-lin ◽  
Wang Zhan-xue ◽  
Zhou Li ◽  
Shi Jing-wei ◽  
Cheng Wen
Keyword(s):  
Aspect Ratio ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Critical Parameters ◽  
Potential Core ◽  
Suppression Effect ◽  
Symmetric Plane ◽  
Flow Features ◽  
In Series ◽  
Jet Characteristics

In order to increase the survivability of the fighter aircraft, the serpentine nozzle has been applied in series of stealth bombers and unmanned aerial vehicles due to its excellent potentiality of evidently suppressing the infrared radiation signatures and radar cross section emitted by engine exhausts. Among the geometric parameters of the serpentine nozzle, the aspect ratio (AR) at the nozzle exit is one of the most critical parameters for the nozzle design as the infrared suppression effect could be greatly enhanced with the increment of AR by strengthening the mixing between the exhaust plume and atmosphere; the aim of this paper is to study the influence of the AR on the flow characteristics of the double serpentine nozzle. The flow features of six double serpentine convergent nozzles, i.e. AR = 3, 5, 7, 9, 11, 15 respectively, were numerically simulated with the shear stress transport κ–ω turbulent model adopted, which had been validated by the experimental data. The characteristics of internal flow and external jet, and the aerodynamic performances of these six nozzles were compared. Results show that the Ma contours at the symmetric plane are different due to the distinct flow accelerations caused by the change of the curvature and the duct height for diverse AR, and the surface pressure and the shock wave features are different correspondingly. The lateral divergence and the lateral convergence characteristics of the nozzle configuration lead to opposite lateral flow under diverse AR, and the change of lateral width induced different lateral pressure gradient, then lead to various lateral vortex distributions. The length of potential core is the contribution of the comprehensive effects of geometry parameters, and it is decreased with the increase of AR due to the dominated effect of the increased mixing area; however, the declining rate is slowed down. The AR of 5 should be chosen for the best aerodynamic performance of the double serpentine nozzle under the qualifications to completely shield the high-temperature turbine.

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