# Semester report on work done towards thesis

- Name: Kamal Kumar Yadav
- Roll: 19205266
- Thesis title: Atomization in effervescent atomizers

## Timeline

- Registration date: 27.12.2019
- Comprehensive: 23.02.2022 (+2 year 2 month from registration; reference date for thesis)
- SOTA: 27.06.2022 (+0 year 4 months)

- National conference 1: ISRO IAES, 04.2024 (+2 year 2 months)
- National conference 2: FMFP, 12.2024 (+2 year 10 months)
- National conference 3: SEEC, 12.2024 (+2 year 10 months)

- Journal article 1: Intl. J. Fluid Mech. Res., 04.2025 (+3 year 2 months)

- Patent application: Indian patent applied, 15.01.2024(+1 year 11 months)

### Planned

- Journal article 2: on cavitation, planned submission 05.2025 (+3 year 3 months)
- Journal article 3: on the effect of bubbles, experiments complete, planned submission 07.2025 (+3 years 5 months)
- Journal article 4: on the effect of fluid properties, experiments complete, planned submission 06.2025 (+3 years 5 months)
- Journal article 5: on the effect of gas injection, experiments pending, planned submission 08.2025 (+3 years 7 months)

- Open seminar: 10.2025 (+3 year 8 months)
- PhD defense: 12.2025 (+3 year 10 months)

## Report for 2024-25 Sem II

### Work done till 2024-25 Sem II

- Test rig and experiment development
- Diagnostics development, including high speed Schlieren with LED.
- Experiments with variation in atomizer geometry, manifold pressure, fluid
property (viscosity, surface tension), Weber number, unsteady
pressure amplitude.
- Analysis of data with variation in manifold pressure, atomizer geometry,
unsteady pressure amplitude and subsequent publication/presentation.
- Characterization of the formation of bubbles with long-term stability.
- Patent application

### Work originally planned

- Develop MATLAB routines for drop size distribution result
- Design and perform experiments on atomization of sprays with air/N2 injection

### Work completed

- Designed experiment including design, fabrication, and purchase of rig parts
and flow control devices for experiments with air/N2 injection.
- Tested the first design iteration of air/N2 injection to the atomizer. The
design is not successful and will be improved. These test are relevant
for the last chapter of the thesis.
- Analysed the images of the spray field for spray angle, breakup length,
periodic structures, and droplet size distribution for different cases
of manifold pressure, atomizer geometry, and unsteady pressure
amplitude. These analyses led to the results in the published IJFMR
article and the in-progress article to be submitted in SoSe 2025.
- Repeated all conditions of DI water with high speed imaging to validate drop size distribution analysis.

### Work carried over

- Design and experiments with air/N2 injection
- Manuscript preparation and submission of data from finished experiments

### New tasks completed

- Rebuttal and revision of the IJFMR paper and acceptance for publication.
- Submission of FMFP work for book chapter
- Full paper submission to ILASS EU
- Learned and implemented POD for spray characterization

### Issues faced

- Analysis of spray field to determine droplet size distribution required
significant investment specially as I am still learning MATLAB and
did not have previous exposure to image processing. I received
considerable help from Rohit Bhattacharjee from Mathworks for this
task. **The tasks is now resolved**
- Repeated imaging of the droplet field had to be conducted with varying
optics for working with the limitation of the resolution limit of
the optics for the measurement of droplets sizes of the order of
100 microns and smaller.
- The planned design for air/N2 addition to study atomization in the presence of external air/N2 injection did work as originally expected. Design iterations and repeated testing of different design ideas will be
necessary.

### DMC Report submission

#### Present status of the thesis

**Work done till 2024-25 Sem II**

- Test rig and experiment development
- Diagnostics development, including high speed Schlieren with LED.
- Experiments with variation in atomizer geometry, manifold pressure, fluid
property (viscosity, surface tension), Weber number, unsteady
pressure amplitude.
- Analysis of data with variation in manifold pressure, atomizer geometry,
unsteady pressure amplitude and subsequent publication/presentation.
- Characterization of the formation of bubbles with long-term stability.
- Patent application

**Status in 2024-25 Sem II**

- Experiments complete for two out of three main sections of results: a. atomization and spray for varying manifold configurations; b. the effect of fluid properties on atomization and spray; c. Effect of air/nitrogen injection on atomization and sprays.
- Analysis for section b and experiments for section c are pending. Expected to complete within SoSe 2025 and Sem 2025-26 I.
- One journal publication complete; four in the pipeline. Expected submission in the coming months.
- Open seminar planned for October 2025

#### Report the progress made as per the Thesis Work Plan(TWP)

As per the plan for this semester,

- progress with analysis is satisfactory although it took longer than expected;
- progress with experiments is slower than expected due to technical issues with the design of air injection -- expected that the delay will be covered in SoSe;
- progress with writing needs extra focus in SoSe; Kamal needs to put additional time to cover writing tasks.

#### Bottleneck and difficulties which needs attention

- Certain planned experiments may need several iterations before expected results are successfully obtained.

## Plan for SoSe 2025

### Conferences

- ILASS-EU, 08.2025

### Experiments

- Design iteration for air/N2 injection for testing bubbly flow atomization
with different fluids.
- Experiments on atomization of bubbly fluids with variation in atomizer
geometry, liquid property, gas-to-liquid ratio, manifold pressure,
and unsteady pressure amplitude.
- Additional characterization of bubbly liquid with GC-MS (gas chromatogrpahy-
mass spectrometry) if required.

### Analysis

- Analysis of data obtained for spray with variation in liquid property.
- Analysis of data obtained for bubbly liquid atomization.
- Analysis of spray structure evolution.
- Comparison of spray structure with predictions in literature; scaling rules.
- Additional analysis of cavitation cloud within manifold.
- Additional analysis of stable bubbles formed within liquid.

### Writing

- Manuscript on cavitation cloud in the manifold.
- Manuscript on the effect of liquid property on atomization.
- Manuscript on stable bubble suspension.

The expected split of effort between the three is 40-30-30 (EWA)

pie title Research effort split
    "Experiments" : 40
    "Writing" : 30
    "Analysis" : 30