INFLUENCE OF INJECTION PRESSURE AND SWIRL

CHAMBER DIAMETER ON JET-SWIRL ATOMIZER SPRAY ANGLE

Zulkifli Abdul Ghaffar, Salmiah Kasolang and Ahmad Hussein Abdul Hamid

Faculty of Mechanical Engineering, Universiti Teknologi MARA (UiTM), Shah Alam,

Selangor

Liquid atomization

Background

Objective

Apparatus & Measurement

Results & Discussions

Conclusions

Applications

Food coating

Fuel injection

Fire suppression

Nasal spray Perfume

Definiton: A process of disintegrating bulk liquid into sprays

Acquired through a device called the atomizer

E.g. jet-swirl atomizer, pneumatic atomizer, ultrasonic atomizer

Jet-swirl atomizer An atomizer in which the liquid is

swirled by means of swirl-generating

vanes before discharge the atomizer

Hamid et al & Laryea et al Studied the influence of injection pressure on the spray

angle of pressure-swirl atomizer

Hussein et al Studied the influence of orifice diameter towards spray

angle of jet-swirl atomizer

Rizk and Lefebvre Studied the influence of swirl chamber diameter and

operating conditions on spray angle of pressure-swirl atomizer

Influence of swirl chamber diameter on pressure-swirl atomizer spray angle has been studied but not on jet-swirl atomizer spray angle

Importance of wider spray angle

Wider spray distribution

In combustion, increase in spray angle increases the exposure of the droplets to the surrounding air or gas, leading to improved and higher rates of heat and mass transfer

To investigate the influence of injection pressure and swirl chamber diameter variation on spray angle of a newly designed jet-swirl atomizers

Atomizer geometries & operating principles

Ato

miz

er

no

.

Geometrical parameters

Vane tip angle,

( )

Swirl chamber diameter, ds (mm)

Swirl chamber length, ls

(mm)

Discharge orifice

diameter, do (mm)

Discharge orifice

length, lo (mm)

1 45 25 40 2.5 5

2 45 40 40 2.5 5

Cold flow test-rig Lab scale

Camera

High-speed camera at 1000fps

Spray angle measurement Video recordings converted to sequence of images

Conversion to binary form

Facilitate spray visualization

Measurement of spray angle

Angle tool in ImageJ

Effect of liquid injection pressure Upon increased, spray angle shows fluctuation with

ds=25mm but remains steady with ds=40mm

Effect of swirl chamber diameter Smaller diameter results in larger spray angle

Relation of liquid injection pressure to volume flowrate Increased with increase of injection pressure

Almost similar values for both swirl chamber diameter

Based on the study, it was found that the increment of injection pressure and reduction of swirl chamber diameter led to the production of a wider spray angle.

In addition, the spray angle was found to be unaffected by the changes of volumetric flow rate.