Characteristics Of Impingement Diesel Spray Adhesion On A Flat Wall

Mohd Zaid, Akop (2014) Characteristics Of Impingement Diesel Spray Adhesion On A Flat Wall. PhD thesis, Universiti Teknikal Malaysia Melaka.

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Many researchers since last decade were looking forward on improving diesel engine performance with keeping low harmful emission. Wall impingement of fuel spray is known as the main contributor to direct injection high-speed diesel combustion, so it becomes an important factor in reducing diesel exhaust emissions. Since the combustion chamber in a diesel engine is too small to mix injected fuel and surrounding gas perfectly, wall impingement of the spray is considered to be inevitable in the engine. Non-evaporated spray research for basic understanding of spray behavior is conducted. The aim of this study is to clarify the fundamental characteristics of non-evaporated impinging spray and adhesion behavior of fuel by measuring the adhering fuel mass on a wall. In this study, a fuel injection system, a high pressure vessel and an image processing unit for impingement spray were used. Experimental investigations were carried out with various injection pressures from 40 MPa to 170 MPa and ambient pressures from 0.1 MPa to 4.0 MPa. The impingement distances were set from 30 mm to 90 mm and various sizes of impingement disk were used. The results show, the adhered fuel mass affected by impingement distances. The adhered mass ratio was inversely proportional to injection pressure. Regardless of injection pressure and impingement distances, it was found that the adhered fuel mass became constant with increasing the diameter of the impingement disk. Thickness of liquid film tended to decrease with increasing of injection pressure. Moreover, the adhered fuel mass ratio decreased with an increase of the inclination angle of disk. General modified adhered mass ratio was introduced to summarize the adhered mass with combinations of various impingement distances, disk sizes, inclination angles and injection pressures. Weber number which was calculated by approaching velocity of droplet to the impingement wall was more dominant factor than the Weber number obtained by droplet absolute velocity. However, the impingement of lower Weber number droplet produced thick film and adhered fuel mass was little influenced by the Weber number. From the results of experimental works, the empirical equations concerning the adhered mass ratio were derived. At higher ambient pressure and higher the injection pressure, adhered mass fuel tended to decrease. As for long impingement distances such as 70 mm and 90 mm, adhered fuel mass in high ambient pressure condition such as 4 MPa was half of that under 1 MPa condition. Finally, it was found that the adhered mass ratio could be correlated by using Weber number and Jet number.

Item Type: Thesis (PhD)
Uncontrolled Keywords: Diesel motor -- Combustion, Diesel motor -- Design and construction, Diesel motor -- Simulation methods
Subjects: T Technology > T Technology (General)
T Technology > TJ Mechanical engineering and machinery
Divisions: Library > Disertasi > FKM
Depositing User: Nor Aini Md. Jali
Date Deposited: 12 Apr 2016 02:56
Last Modified: 12 Apr 2016 02:56
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