Acoustic Measurements for Hexagonal Pipe Jet Flow

The research paper aims to understand the acoustic behavior of hexagonal pipe jet flow. The length to diameter ratio of pipe is 6. The circular equivalent diameter (D
e
) is 5 mm. The Nozzle Pressure Ratio is from 2 to 6. The emission angles (ϕ) considered are 60° and 90° measured from downstream direction (jet axis). The Sound Pressure Level (SPL) and Over All Sound Pressure Level (OASPL) are compared for the two emission angles. The 90° emission angle has more harmonic peaks comparatively. The number of screech harmonics increases as NPR increases from 4 to 6. The maximum OASPL difference among the emission angles are also made and it is found to decrease with increase in NPR. The Schlieren flow visualization is done to support the acoustic data qualitatively.