Discipline: Technology and Engineering
Subcategory: Physics (not Nanoscience)
Javis Howard - Tuskegee University
Co-Author(s): David Alexander IV, Tuskegee University, Tuskegee, AL; Leavohn Lewis, Tuskegee University, Tuskegee, AL
Studies involving high speed flow mixing is challenging due to less resident time and high diffusion rate requirement in combustors. For example, in a scramjet engine, it is very important for fluids to mix effectively within a short period of time for an efficient combustion. Moreover, the fuel penetration into the boundary layer of the incoming fluid requires high momentum injection techniques. To resolve mixing challenges, active flow control techniques can be used. At Tuskegee University, we designed and developed a resonance enhance microactuator (REM) nozzle for high speed flow mixing. The REM nozzle is designed to steadily inject fluid through four micronozzles of diameter 400 ?m which are evenly positioned around a 1 mm nozzle where a pulsed supersonic jet with high frequency exits [1 and 2].
In this abstract we report quantitative evidence of the Mach disk oscillations of the REM-nozzle source jet and the velocity of vortices present in the supersonic pulsed flow. A micro-schlieren system has been used to acquire images at a frame rate of 64,000 fps using a high-speed camera. A LED light source with pulse width less than 80ns and a microphone were also used for data/image acquisition for this study. Compressed nitrogen and air were used for experiments. Software including MATLAB and LabVIEW were used to acquire and process data.
Due to the high speed and size of the evolving jets, quantification is extremely challenging. However, this system provides an excellent source to study high speed turbulent flow. In this study, we calculated the velocity and frequency of Mach disk oscillations associated with REM nozzle and the vortex velocity of the supersonic jet. To obtain quantitative data, pixels contained in the images were scaled to obtain the distance travelled and using the corresponding time signatures from the frames, the Mach disk oscillation frequency and vortex velocities were evaluated. The average velocity of the Mach disk oscillations was 4.52 m/s while the average vortex velocity calculated to be 212.10 m/s [3]. These oscillations occurred at a frequency of 12.82 kHz which is consistent with the previous data. Based on the evidence obtained, we plan to complete more research with different fluids to verify existing data and compile more data to further characterize the REM nozzle.
Funder Acknowledgement(s): Funding was provided by NSF/ HBCU-UP grant to Dr. John Solomon.
Faculty Advisor: Dr. John Solomon, jsolomon@tuskegee.edu
Role: To obtain quantitative data, pixels contained in the images were scaled to obtain the distance travelled and using the corresponding time signatures from the frames, the Mach disk oscillation frequency and vortex velocities were evaluated. The average velocity of the Mach disk oscillations was 4.52 m/s while the average vortex velocity calculated to be 212.10 m/s [3]. These oscillations occurred at a frequency of 12.82 kHz which is consistent with the previous data