11/09/2026
By Thomas Dugan

The Francis College of Engineering, Department of Mechanical Engineering, invites you to attend a master’s thesis defense by James Kiikka, titled “Processing Pipeline for Non-Uniform Spatiotemporal Measurements of Anisotropy in Propeller Shear Layers Using a Discrete Point Pressure Probe.”

Details

  • Date: Tuesday, Nov. 17, 2026
  • Time: 9:30 – 11 a.m.
  • Location: Falmouth 311

Committee members

  • Murat Inalpolat, advisor, professor and associate chair for doctoral studies, Mechanical Engineering, UMass Lowell
  • David J. Willis, professor, Mechanical Engineering, UMass Lowell
  • Christopher Niezrecki, professor, Mechanical Engineering, UMass Lowell

Abstract

Urban air mobility is a rapidly developing transportation sector that relies heavily on electric propulsion and has the potential to become an important part of future urban transportation. As these systems are implemented, understanding and managing their acoustic-noise profiles will be essential at both the system and component levels.

One important source of noise is the interaction between propeller blades and other airframe-mounted structures. Propellers, wings and fuselages can produce increased acoustic noise when they interact with atmospheric turbulence. The characteristics of that turbulence, including its magnitude and geometric pattern, can affect the resulting noise. Propeller blades also generate turbulent structures through shear-layer and fluid-loading effects.

Previous research has quantified the kinetic energy of turbulence behind aircraft propellers using particle-image velocimetry and hot-wire anemometry. However, relatively few studies have examined anisotropic effects in marine propeller wakes, and aircraft-propeller wakes differ substantially in geometry and operating conditions. Although turbulence anisotropy has been observed in blade-tip vortices, anisotropy tensors and their invariants have not been fully examined for aircraft propellers.

This thesis investigates the anisotropic stress tensors of turbulence and their invariants within the wakes of propellers used in urban air-mobility vehicles. It develops an algorithmic pipeline for processing time-coherent, discrete-point turbulence measurements obtained through a pressure-based probe during a spatial scan with a non-uniform sampling rate.

The method is designed to support measurements of turbulence structures in a non-rotating reference frame using a hand-held scanning pressure probe. It also enables the estimation of turbulence anisotropy in urban-air-mobility propeller wakes. The resulting processing pipeline provides a more comprehensive understanding of the anisotropic turbulence patterns generated by propellers and their potential influence on acoustic-noise levels.