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Research Papers: Gas Turbines: Combustion, Fuels, and Emissions

The Influence of Actual Layout and Off-Axis Needle Stroke on Diesel Nozzle Flow Under Ballistic Needle Displacement

[+] Author and Article Information
Fulvio Palmieri

Dipartimento di Ingegneria,
Università degli Studi Roma Tre,
Via della Vasca Navale 79-81,
Roma 00146, Italy
e-mail: fulvio.palmieri@uniroma3.it

The hole plane is defined as the plane containing the circle that passes through the centers of the nozzle holes.

Contributed by the Combustion and Fuels Committee of ASME for publication in the Journal of Engineering for Gas Turbines and Power. Manuscript received June 26, 2013; final manuscript received July 9, 2013; published online September 6, 2013. Editor: David Wisler.

J. Eng. Gas Turbines Power 135(10), 101502 (Sep 06, 2013) (7 pages) Paper No: GTP-13-1181; doi: 10.1115/1.4024986 History: Received June 26, 2013; Revised July 09, 2013

The injection of small amount of diesel fuel relies on the shortening of energizing signal. In such injection conditions, the needle does not reach the mechanical stroke-end and its displacement is defined as ballistic. Some specific experimental work has been performed on how the dynamics of injector needle is reflected on the fuel flow pattern within the nozzle. Due to the intrinsic difficulties of the field, just single axial hole injectors have been optically investigated in real time, by means of the most advanced X-ray techniques. In the current study, based on 3D-computational fluid dynamics modeling, the investigation has been extended to multihole injector layouts, under typical pilot/split injection conditions, namely, high injection pressure and low needle lift. The role of different factors on the flow development within the nozzle has been shown and discussed; the investigations have taken into account actual injector tip layouts and the response to the needle off-axis operating conditions. Results are presented highlighting the flow features within the nozzle and their reflects on the hole-to-hole differences.

Copyright © 2013 by ASME
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References

Figures

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Fig. 1

Single-axial-hole nozzle

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Fig. 2

Five-hole “fully axial” nozzle layout

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Fig. 3

Internal nozzle layout after optical investigation; needle lift off-axis scheme is represented by A-B line

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Fig. 4

Five-hole nozzle with inclined injector axis

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Fig. 5

View of a CR injector on engine head (18 deg hole plane angle)

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Fig. 6

Injector model sketch in AMESim environment

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Fig. 7

Needle lift time trace

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Fig. 8

Off-axis case, vector velocity field (m/s); initial phase of injection

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Fig. 9

Off-axis case, vector velocity field (m/s); central phase of injection

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Fig. 10

Off-axis case, liquid volume fraction (-); initial phase of injection

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Fig. 11

Off-axis case, liquid volume fraction (-); central phase of injection

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Fig. 12

Off-axis multihole case, scalar velocity field (m/s); initial phase of injection

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Fig. 13

Off-axis multihole case, scalar velocity field (m/s); central phase of injection

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Fig. 14

Nondimensional flow rate comparison for off-axis cases. 11

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Fig. 15

Liquid volume fraction (-), multihole case at central phase of injection–off axis

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Fig. 16

Liquid volume fraction (-), multihole case at central phase of injection–fully axial

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Fig. 17

Specific turb. kinetic energy comparison for off-axis cases

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Fig. 18

Liquid volume fraction comparison for off-axis cases

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Fig. 19

Inclined multihole case, liquid volume fraction (-); central phase of injection

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Fig. 20

Inclined multihole case, scalar velocity field (m/s); initial phase of injection

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Fig. 21

Inclined multihole case, scalar velocity field (m/s); central phase of injection

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Fig. 22

Nondimensional flow rate comparison for inclined cases

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Fig. 23

Nondimensional flow rate comparison for inclined cases

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Fig. 24

Specific turb. kinetic energy comparison for inclined cases.

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Fig. 25

Liquid volume fraction comparison for inclined cases Table 1 Specifications of injection system

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