Effects of specific heat ratio on a simulated chemical-laser-cavity flow. Master's thesis

Technical Report · Fri Nov 30 23:00:00 EST 1990

OSTI ID:5688428

Botts, C D

Mixing of primary cold flow air and secondary helium to control the ratio of specific heats for the medium flowing through a simulated chemical laser nozzle/lasing cavity was accomplished. The effects of a range of mixture specific heat ratios on flowfield behavior were examined using static pressure ports in the test cavity. Schlieren photography and high speed filming aided description of the flow dynamics. Results indicated that boundary layer effects became evident in the nozzles as specific heat ratios increased. Large pressure fluctuations were observed in the cavity when helium was introduced into the flow to raise the specific heat ratio. This unstable behavior was attributed to the helium mass flow into the mixer and the mixer design itself. Use of the air/helium mixer brought about the pressure fluctuations earlier in a test run than with than with the mixer removed under the same conditions. Favorable pressure conditions for lasing were achieved for at least two seconds for the supersonic nozzles' design specific heat ratio of 1.51. Adverse pressure behavior was also attributed to three dimensional viscous effects along the cavity walls. (JHD)

• Research Organization: Air Force Inst. of Tech., Wright-Patterson AFB, OH (USA). School of Engineering
• OSTI ID: 5688428
• Report Number(s): AD-A-230459/0/XAB; AFIT/GAE/ENY--90-3
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
426002* -- Engineering-- Lasers & Masers-- (1990-)
AIR
BEHAVIOR
CAVITIES
CHEMICAL LASERS
CONTROL
DISPERSIONS
DYNAMICS
ELEMENTS
FLUID FLOW
FLUID MECHANICS
FLUIDS
GASES
HELIUM
LASER CAVITIES
LASERS
MASS TRANSFER
MECHANICS
MIXING
MIXTURES
NONMETALS
NOZZLES
PHOTOGRAPHY
PHYSICAL PROPERTIES
RARE GASES
SCHLIEREN METHOD
SIMULATION
SPECIFIC HEAT
THERMODYNAMIC PROPERTIES
VISCOSITY
WALLS