PhD Defence: Raghav Sikka

Raghav Sikka will be defending his thesis for the degree of philosophiae doctor (PhD).

12 Dec

Practical information

  • Date: 12 December 2022
  • Time: 09.30 - 15.00
  • Location: Porsgrunn, auditorium A-271 og på Zoom
  • Download calendar file

    • Zoomlink

    Programme

    Kl. 09.30 Trial Lecture Topic: Droplets in Combustion

    Kl. 12.00 PhD defense: Characterization of the Spray for Twin-Fluid Atomizer for Inert Gas Generator

    Evaluation committee:

    • First opponent: Professor Andrzej Teodorczyk, Warsaw University of Technology
    • Second opponent: Dr. Espen Åkervik, Forsvarets forskningsinstitutt (FFI)
    • Third opponent and administrator of the committee: Professor Karina Bakkeløkken Hjelmervik, USN

    Principal supervisor:

    • Associate professor Joachim Lundberg (USN)

    Co-supervisors:

    • Professor Knut Vågsæther (USN)
    • Professor Dag Bjerketvedt (USN)

     

    Both the trial lecture and the PhD defense are open to the public. Immediately after the defence the doctoral programme will hold a small defence reception outside A-271, approximately from 15:00-15:30.

Any questions?

Raghav Sikka at the University of South-Eastern Norway, Faculty of Technology, Natural Sciences and Maritime Sciences (TNM) will be defending his thesis for the degree of philosophiae doctor (PhD).

Title of thesis: “Characterization of the Spray for Twin-Fluid Atomizer for Inert Gas Generator”

Raghav SikkaSummary:

Wärtsilä Moss AS design and develops gas handling systems for marine and industrial purposes. The gas handling system have two important purposes: 1. handeling boil of gas, 2. produsing inert gas. A crucial element of this type of equipment is a diesel spray flame. Efficient combustion is a crucial part both in terms of propulsion and providing an inert environment in combustible surroundings. The combustion efficiency depends upon the fuel vaporization and thus, fuel-air mixing. The diesel fuel must be atomized in a mechanical device called an atomizer. The atomizer design is pivotal in the quality of atomization in terms of drop sizes, droplet size distribution and spray pattern. Therefore, a detailed study was carried out with the novel atomizer designs to characterize the different spray properties.


In the first phase of the study, two simpler twin-fluid atomizer designs (converging and converging-diverging (CD) interior for airflow) were employed to examine the fundamental mechanics of the sheet breakup mechanism. Six different breakup modes were identified at different fluid flow rates (both water & air). The breakup length and spray angle was also quantified to comprehend the spray formation dynamics. The drop size and drop size distribution were also characterized, with smaller drop sizes and narrower distribution for CD atomizer designs. The breakup modes and drop sizes were also predicted through modelling using Principal Component Analysis (PCA) and Partial Least Squares-regression (PLS-R). In the second phase, the bluff body atomizers (cone attached) were incorporated, and the spray was characterized based on the cone distance (Lc) variation and airflow diameters (d) in terms of drop size, drop size distribution and spray pattern (Patternation technique). The spray drops size increases, while drop size distribution broadens while moving radially away from the spray centreline. The spray drop sizes were also predicted through modelling using PCA and PLS-R in this case. The findings presented in the thesis are industry relevant and could be used for simulations, CFD calculations, recommendations, and standards. The work was carried out at the University of South-Eastern Norway with the assistance of Wärtsilä Moss AS.