The Effect of the Fuel Injector Internal Geometry Upon the Primary Zone Aerodynamics

1998 ◽  
Author(s):  
R. A. Hicks ◽  
M. Whiteman ◽  
C. W. Wilson
Keyword(s):  
Boundary Conditions ◽  
Fluid Dynamic ◽  
Radial Component ◽  
Fuel Injector ◽  
Air Blast ◽  
Fuel Injectors ◽  
Cfd Models ◽  
Primary Zone ◽  
Flow Through ◽  
Semi Empirical

One of the major aims of research in gas turbine combustor systems is the minimisation of non-desirable emissions. The primary method of reducing pollutants such as soot and NOx has been to run the combustion primary zone lean. Unfortunately, this causes problems when the combustor is run under idle and relight conditions as the primary zone air fuel ratio (AFR) can exceed the flammability limit. Altering this AFR directly affects the primary zone aerodynamics through changes in the spray profile. One method of determining the influence of changes in AFR upon the primary zone is to use Computational Fluid Dynamic (CFD) models. However, to model the flow through an air-blast fuel injector and accurately predict the resulting primary zone aerodynamics requires hundreds of thousands, if not millions, of cells. Therefore, with current computer capabilities simplifications need to be made. One simplification is to model the primary zone as a 2-D case. This reduces the number of cells to a computationally solvable level. However, by reducing the problem to 2-D the ability to accurately model air-blast fuel injectors is lost as they are intrinsically 3-D devices. Therefore, it is necessary to define boundary conditions for the fuel injector. Currently, due to difficulties in obtaining experimental measurements inside a air-blast fuel injector, these boundary conditions are often derived using semi-empirical methods. This paper presents and compares two such models; the model proposed by Crocker et al. in 1996 and one developed at DERA specifically for modelling air-blast fuel injectors. The work also highlights the importance of the often neglected radial component upon the primary zone aerodynamics.

Paper 18: Fluid Dynamic Aspects of Unsteady Flow in Branched Ducts

1967 ◽  
Vol 182 (8) ◽  
pp. 167-174 ◽  
Author(s):  
B. E. L. Deckker ◽  
D. H. Male
Keyword(s):  
Boundary Conditions ◽  
Unsteady Flow ◽  
Fluid Dynamic ◽  
High Amplitude ◽  
Quantitative Information ◽  
Schlieren Method ◽  
Pressure Losses ◽  
Static Pressure Distribution ◽  
Flow Through ◽  
Hydraulic Analogy

Unsteady flow through three-branched pipe configurations has been investigated with the object of finding boundary conditions suitable for use in the analysis of high-amplitude waves using the method of characteristics. The schlieren method and the hydraulic analogy were used to obtain qualitative information about the quasi-steady flow patterns. Quantitative information concerning these patterns was obtained by the measurement of stagnation pressure losses and of the static pressure distribution. Several methods of deriving boundary conditions have been reviewed, and it is considered that those obtained directly by experiment are the most convenient to use.

scholarly journals Summary on the Results of Two Computational Fluid Dynamic Benchmarks of Tube and Different Channel Geometries

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Attila Kiss ◽  
Andrey Churkin ◽  
Darwan S. Pilkhwal ◽  
Abhijeet M. Vaidya ◽  
Walter Ambrosini ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Boundary Conditions ◽  
Computational Fluid Dynamic ◽  
Prediction Accuracy ◽  
Fluid Dynamic ◽  
Annular Channel ◽  
Initial Boundary ◽  
Sensitivity Analyses ◽  
Cfd Models

Two computational fluid dynamic (CFD) benchmarks have been performed to assess the prediction accuracy and sensitivity of CFD codes for heat transfer in different geometries. The first benchmark focused on heat transfer to water in a tube (first benchmark), while the second benchmark covered heat transfer to water in two different channel geometries (second benchmark) at supercritical pressures. In the first round with the experimental data unknown to the participants (i.e., blind calculations), CFD calculations were conducted with initial boundary conditions and simpler CFD models. After assessment against measurements, the calculations were repeated with the refined boundary conditions and material properties in the follow-up calculation phase. Overall, the CFD codes seem to be able to capture the general trend of heat transfer in the tube and the annular channel but further improvements are required in order to enhance the prediction accuracy. Finally, sensitivity analyses on the numerical mesh and the boundary conditions were performed. It was found that the prediction accuracy has not been improved with the introduction of finer meshes and the effect of mass flux on the result is the strongest among various investigated boundary conditions.

Simulating Diesel Injectors Based on Different Cavitation Modeling Approaches

2005 ◽  
Author(s):  
Ming Li ◽  
Aditya Mulemane ◽  
Ming-Chia Lai ◽  
Ramesh Poola
Keyword(s):  
Single Phase ◽  
Discharge Coefficient ◽  
Fluid Dynamic ◽  
Injection Pressure ◽  
Internal Flow ◽  
Fuel Injector ◽  
Modeling Approaches ◽  
Injector Nozzle ◽  
Flow Through ◽  
Two Phases

Computational Fluid Dynamic (CFD) results of different diesel fuel injector nozzle configurations using commercially available CFD codes are presented in this paper. The emphasis of the study is on comparing various cavitation modeling approaches by means of single-phase and two-phases. Results are compared for various diesel injector nozzles and observed to substantiate some of the experimentally established facts such as nozzle efficiency improvements by using techniques like rounded orifice inlets and conical orifices. The effects of needle lift and injection pressure on forming cavatation are also investigated. These simulation results agree well with the experimental results. Parameters like discharge coefficient, Cd and initial amplitude factor, amp0 are used to characterize the internal flow through the nozzle orifices.

scholarly journals Computational and Experimental Evaluation of Integral Catalytic Ignitor/Injector for Gas Turbine Applications

1997 ◽  
Author(s):  
Greg S. Jackson ◽  
Shahrokh Etemad ◽  
Hasan Karim ◽  
William C. Pfefferle
Keyword(s):  
Gas Turbine ◽  
Central Region ◽  
Experimental Evaluation ◽  
Flame Stability ◽  
Computational Results ◽  
Fuel Injector ◽  
Nox Formation ◽  
Air Blast ◽  
Primary Zone ◽  
Combustor Liner

The provision of an ignition source in the central region of a liquid-fired combustor reduces the requirement for wide spray angles, rich primary zones, and their associated performance drawbacks such as high levels of soot and NOx formation and high liner wall temperatures. Various ignition devices have been considered for providing centrally located ignition sources. The current paper presents a study of one alternative concept — the integral catalytic torch ignitor/injector — as a means for providing both combustor light-off and enhanced flame stability in the combustor primary zone. An integral catalytic torch in a fuel injector offers the potential to significantly improve ignition arid flame stability and thus the opportunity to operate combustor primary zones at leaner conditions, which may improve emissions, pattern factor, and combustor liner durability. This paper presents computational and experimental results for a conventional liquid-fired combustor with the addition of a catalytic torch (replacing the pilot pressure atomizer) down the centerline of an air-blast fuel injector. The benefits of a lean primary zone with an integral catalytic torch/injector were investigated both computationally and experimentally by comparing combustor performance with standard and successively leaner primary zones. Pattern factor and emissions are compared with different primary zone jet configurations to observe if the central torch can enhance the operability of leaner primary zones in conventional combustor geometries. The experimental and computational results suggest that the integral catalytic torch can provide more than adequate ignition capabilities with improved combustor emissions when it is combined with a relatively lean operating primary zone.

scholarly journals Development of a Coal-Fueled Gas Turbine Slagging Combustor

1989 ◽  
Author(s):  
L. H. Cowell ◽  
R. T. LeCren
Keyword(s):  
Gas Turbine ◽  
Computer Modelling ◽  
Combustion Process ◽  
Development Program ◽  
Water Mixture ◽  
Fuel Injector ◽  
Cross Sectional ◽  
Fuel Injectors ◽  
Primary Zone ◽  
Multiple Jets

A slagging combustor for a coal-fueled gas turbine engine is being developed. The work to date has been accomplished using a bench-scale combustor with one-tenth the heat input required for the full-scale gas turbine unit. The combustor features a fuel-rich slagging primary zone with hot refractory walls. Both single and multiple primary air/fuel injectors have been tested. Aerodynamic jet impaction on a target at one end of the primary zone removes much of the slag. The jet impaction is the result of the single air/fuel injector flow for multiple injectors, the intersection of the multiple jets forms a central jet. There is an additional particulate rejection impact separator between the primary and secondary zones to remove the slag that escapes the primary zone. Secondary air is introduced via multiple jets that rapidly mix with the incoming gas from the particulate removal device, resulting in a minimal formation of thermal NOx and the completion of the combustion process. Variables that have been evaluated include coal-water mixture properties such as top and mean particle size, viscosity, loading and ash fusion temperature, and primary zone parameters such as volume, cross-sectional area, loading, and equivalence ratio. Combustor performance was compared with single or multiple fuel injectors, relating the combustor performance to the spray characteristics of the two injector configurations. Modifications of the single injector were evaluated with the goal of attaining at least the same atomization performance as the smaller injectors used in the multiple injector configuration. Flow visualization, computer modelling, and cold-flow velocity traverses have been employed to aid the development program. The results of the subscale development are being used to design and develop the full-size combustor for integration with the engine.

Study of fluid flow through a channel deformed by piezoelement

2018 ◽  
Vol 13 (3) ◽  
pp. 1-10 ◽  
Author(s):  
I.Sh. Nasibullayev ◽  
E.Sh Nasibullaeva ◽  
O.V. Darintsev
Keyword(s):  
Fluid Flow ◽  
Pressure Drop ◽  
Boundary Conditions ◽  
Flow Rate ◽  
Contact Surface ◽  
Piezoelectric Element ◽  
Neumann Boundary ◽  
Differential Pressure ◽  
Physical Parameters ◽  
Flow Through

The flow of a liquid through a tube deformed by a piezoelectric cell under a harmonic law is studied in this paper. Linear deformations are compared for the Dirichlet and Neumann boundary conditions on the contact surface of the tube and piezoelectric element. The flow of fluid through a deformed channel for two flow regimes is investigated: in a tube with one closed end due to deformation of the tube; for a tube with two open ends due to deformation of the tube and the differential pressure applied to the channel. The flow rate of the liquid is calculated as a function of the frequency of the deformations, the pressure drop and the physical parameters of the liquid.

scholarly journals A Simple Transient Poiseuille-Based Approach to Mimic the Womersley Function and to Model Pulsatile Blood Flow

Dynamics ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 9-17
Author(s):  
Andrea Natale Impiombato ◽  
Giorgio La Civita ◽  
Francesco Orlandi ◽  
Flavia Schwarz Franceschini Zinani ◽  
Luiz Alberto Oliveira Rocha ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Boundary Conditions ◽  
Quadratic Function ◽  
Pulsatile Blood Flow ◽  
Flow Through ◽  
Simplified Analysis ◽  
Function Models ◽  
Flow Reversals

As it is known, the Womersley function models velocity as a function of radius and time. It has been widely used to simulate the pulsatile blood flow through circular ducts. In this context, the present study is focused on the introduction of a simple function as an approximation of the Womersley function in order to evaluate its accuracy. This approximation consists of a simple quadratic function, suitable to be implemented in most commercial and non-commercial computational fluid dynamics codes, without the aid of external mathematical libraries. The Womersley function and the new function have been implemented here as boundary conditions in OpenFOAM ESI software (v.1906). The discrepancy between the obtained results proved to be within 0.7%, which fully validates the calculation approach implemented here. This approach is valid when a simplified analysis of the system is pointed out, in which flow reversals are not contemplated.

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