Initial Results from a Cryogenic Coaxial Injector in an Acoustic Field
Abstract
A coaxial injector was made to inject liquid nitrogen (LN2) with a coflow of gaseous nitrogen (GN2) in its annular region as part, of a program to better understand the nature of the interaction between acoustic waves and liquid fuel jets in cryogenic rocket engines. The LN2 was injected into a room temperature high-pressure chamber having optical access on its sides. A piezo-siren capable of generating sound waves with an SPL of up to 180 dB was employed under two chamber pressures of 2.14 and 4.86 MPa. The reduced pressures for these pressures are 0.63 (subcritical), and 1.43 (supercritical), respectively. The assembly consisting of the acoustic driver and the high-pressure chamber form a cavity that resonates at several frequencies, the strongest being at 2700 and 4800 Hz. Initial results for only one LN2 flow rate but at three co-flow rates and at 2700 Hz are reported here. The nature of the aforementioned interactions has been captured via a CCD camera high-speed imaging system. These evidences indicate that the warmer co-flow GN2 affects the thermodynamic condition of the LN2 jet near the inner wall surface, reducing the jet initial visual diameter, particularly at higher co-flow rates. Dramatic effects of the periodic transverse acoustic waves can be seen to impose a sinusoidal shape to the jet appearance. The wavelength of this wavy shaped structure is established by the acoustic-induced transverse deflection of the jet considering the fact that the jet exists in the velocity anti- node of the acoustic field.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 09, 2002
- Accession Number
- ADA410882
Entities
People
- B. Chehroudi
- D. Talley
- Dustin Davis
Organizations
- Air Force Research Laboratory