Fluid Mechanics / Experimentation

Air Bubble Drag Reduction

Experimental fluid-mechanics researchExperimental designer and data analyst

Project context

Air lubrication can reduce hull skin-friction drag by introducing a bubble layer between the wetted surface and surrounding water. The project used physical model tests to determine how controllable design and operating variables affect drag-reduction efficiency, while documenting the measurement limitations of an open-water test environment.

Role overview

Shaofu designed hull models and interchangeable air-outlet fixtures, measured towing resistance before and after air injection, and used MATLAB regression to relate relative hull-water speed to drag-reduction performance.

Technical scope

Defined drag-reduction efficiency as the normalized change between baseline and air-assisted resistance measurements.
Varied relative hull-water velocity, vertical outlet count and position, outlet diameter, and hull geometry through controlled model-scale comparisons.
Designed and fabricated hull components and interchangeable air-outlet fixtures for repeatable test configurations.
Processed force measurements in MATLAB and fitted a regression model to quantify the relationship between relative speed and drag reduction.
Evaluated uncertainty from wind loading, surface waves, and nonuniform air delivery when interpreting the results.

Outcome

Observed drag-reduction efficiency increase with relative speed before approaching a stable operating region.
Found that two centrally located outlets produced the strongest result among the tested placement configurations.
Observed improved performance from smaller outlet diameters within the evaluated range, while hull-form effects were comparatively limited.
Established a repeatable test framework for future CFD correlation and higher-fidelity towing experiments.

Experimental study
Research poster documenting the physical models, test variables, data reduction, uncertainty analysis, and experimental findings.