Discipline: Technology and Engineering
Subcategory: Civil/Mechanical/Manufacturing Engineering
David Alexander IV - Tuskegee University
Co-Author(s): Kyran Caines, Frederic Higgins, and Micheal Jones, Tuskegee University, Tuskegee, AL
Flow instabilities are inherent in high speed flow applications and play a crucial role for generating hostile dynamic interactions in fluids. With flow control schemes, these inherent instabilities can be tailored to achieve favorable outcomes. The resonance enhanced micro-actuator nozzle (REM-nozzle) used in this research is a device developed for high speed flow control. This type of fluidic actuator, having neither heavy nor complicated hardware/electronics, was observed to provide high momentum perturbations over a wide range of frequencies (1- 60 kHz). The REM has been designed and tested by several researchers for various flow control applications. In this research, we use REM technology to design fuel nozzles applicable for high speed combustors. The REM nozzle design is composed of 4 major elements. An under expanded source jet from a 1mm nozzle, a constricted cavity, 4 micro-nozzles through which the pulsed high frequency micro-jets flow out, surrounding a 1mm nozzle through which the nozzle jet is flown out. A semi-empirical correlation derived by Solomon  is used for designing REM nozzles. A novel high-speed flow mixing technique using high frequency pulsed microactuators will be reported in this paper. A jet injection assembly integrated with high frequency (15-21 kHz) pulsed microactuators (known as resonance enhanced microjets – REM) has been developed and tested. The resonance enhanced microactuator nozzle system (REM – Nozzle) can steadily inject a fluid through four micro-nozzles of 400 μm diameter positioned around a 1 mm nozzle through which the high frequency, pulsed supersonic actuation jet flows out. An experimental fluid, CO2, is used for the high-speed mixing experiments to characterize the REM nozzle at various conditions. The high frequency pulsed air jet develops strong compressible vortex pairs in this frequency that entrain the fluid injected close to their initial formation. This high frequency vortex with entrained fluid grows further in the stream wise direction enhancing better mixing of the fluids at very high-speed. Such nozzles can potentially be used to enhance mixing inside a high speed combustor. The noise-field and mixing characteristics of this nozzle will be presented.
Funder Acknowledgement(s): Funding was provided by NSF/ HBCU-UP grant.
Faculty Advisor: John Solomon, JSolomon@mytu.tuskegee.edu
Role: I designed the REM nozzle actuator tested in the study using the REM nozzle criteria and frequency correlation. I designed the experimental set up to obtain quality data in order to properly characterize the REM nozzle actuator. I developed the matlab code for the video sequencing of the pulsing actuator.