01/15/2024
By Danielle Fretwell

The Francis College of Engineering, Department of Mechanical Engineering, invites you to attend a Doctoral Dissertation Proposal defense by Aman Kumar on: Investigation and Development of Flash Boiling Model for Gasoline and Ammonia.

Candidate Name: Aman Kumar
Degree: Doctoral
Defense Date: Wednesday, Jan. 24, 2024
Time: 1 - 3 p.m. EDT
Location: Southwick 240

Committee:

  • Advisor: Noah Van Dam, Assistant Professor, Mechanical & Industrial Engineering, UMass Lowell
  • John Hunter Mack, Associate Professor, Mechanical & Industrial Engineering, UMass Lowell
  • Juan Pablo Trelles, Professor, Mechanical & Industrial Engineering, UMass Lowell
  • David Schmidt, Professor, Mechanical & Industrial Engineering, UMass Amherst

Brief Abstract:
Ammonia is being considered as part of the future energy fuel mix along with other light molecular weight fuels such as Di-methyl ether (DME), methanol, etc. Ammonia’s easy synthesis capability, combustion and other properties empower it to be a strong candidate in the coming energy transition. However, ammonia and many of the other proposed non-carbon or net zero carbon fuels have a stronger tendency to flash boil under standard engine operating conditions and a comprehensive understanding of modeling of flashing sprays for future engine development work is needed.

Parcel-based simulations are the most common method to simulate fuel sprays, due to their lower computational cost compared to more highly resolved simulations. However, recent advances in computational power and numerical methods, have made it possible to resolve flow through injector tip geometry which was not considered previously in parcel-based simulations. Four different geometric parameters were investigated related to geometry setup and parcel initialization. The fifth parametric variation was chosen to be turbulence model, changed between Reynolds Averages Navier-Stokes (RANS) and Large-eddy Simulation (LES). These simulations were compared with global and local experimental data at non-flash boiling condition, and then tested for flash boiling condition.

Overall, this study would capture the intricate detail at near nozzle region which prone to intense flashing. This would help to establish case setup for Ammonia parcel-based simulation.

Further, Flash boiling simulation was conducted with high fidelity Volume of Fluid (VoF) method using Homogenous Relaxation Model (HRM) to replicate real life simulation details. However, discrepancy in vapor generation was observed with simulation time scale changes.
So, a simplified geometry is simulated to understand the vapor generation rate due to temporal variation and tentatively correlate with characteristics time constant of phase change process.