Experimental Studies of the Effect of Gravity on the Stability of Premixed Laminar Flames
Title | Experimental Studies of the Effect of Gravity on the Stability of Premixed Laminar Flames PDF eBook |
Author | Corey Martin Dunsky |
Publisher | |
Pages | 642 |
Release | 1991 |
Genre | |
ISBN |
Scientific and Technical Aerospace Reports
Title | Scientific and Technical Aerospace Reports PDF eBook |
Author | |
Publisher | |
Pages | 500 |
Release | 1995 |
Genre | Aeronautics |
ISBN |
Experimental Investigation of Laminar Gas Jet Diffusion Flames in Zero Gravity
Title | Experimental Investigation of Laminar Gas Jet Diffusion Flames in Zero Gravity PDF eBook |
Author | Thomas H. Cochran |
Publisher | |
Pages | 38 |
Release | 1971 |
Genre | Combustion |
ISBN |
An experimental program was conducted to study the burning of laminar gas jet diffusion flames in a zero-gravity environment. The tests were conducted in the Lewis Research Center's 2.2- Second-Zero-Gravity Facility and were a part of a continuing effort investigating the effects of gravity on basic combustion processes. The photographic results indicate that steady state gas jet diffusion flames existed in zero gravity but they were geometrically quite different than their normal-gravity counterparts. Methane-air flames were found to be approximately 50 percent longer and wider in zero gravity than in normal gravity.
Effects of Gravity on Laminar Gas Jet Diffusion Flames
Title | Effects of Gravity on Laminar Gas Jet Diffusion Flames PDF eBook |
Author | Thomas H. Cochran |
Publisher | |
Pages | 34 |
Release | 1970 |
Genre | Space vehicles |
ISBN |
An experimental program was conducted to study the burning of laminar gas jet diffusion flames in a zero-gravity environment. The tests were conducted in the Lewis Research Center 2.2-Second Zero-Gravity Facility. The photographic results indicated that a sudden decrease in gravity level from 1 to 0 effected an immediate reduction in the length of the flame. Continued time in zero gravity resulted in the flame expanding away from the burner until extinguishment appeared to occur. Nondimensionalization of the governing flow equation yielded the parameters used to correlate the buoyancy effects.
An Experimental and Numerical Study on the Stability and Propagation of Laminar Premixed Flames
Title | An Experimental and Numerical Study on the Stability and Propagation of Laminar Premixed Flames PDF eBook |
Author | Christina M. Vagelopoulos |
Publisher | |
Pages | 350 |
Release | 1999 |
Genre | |
ISBN |
NASA Technical Memorandum
Title | NASA Technical Memorandum PDF eBook |
Author | |
Publisher | |
Pages | 492 |
Release | 1994 |
Genre | Aeronautics |
ISBN |
The Stability and Structure of Lean Hydrogen-air Flames
Title | The Stability and Structure of Lean Hydrogen-air Flames PDF eBook |
Author | G. Patnaik |
Publisher | |
Pages | 15 |
Release | 1990 |
Genre | Combustion |
ISBN |
Detailed, time-dependent, two-dimensional numerical simulations with full hydrogen-oxygen chemistry are used to investigate the effects of gravity on the stability and structure of laminar flames in lean, premixed hydrogen - air mixtures. The calculations show that the effects of gravity becomes more important as the lean flammability limit is approached. In a 12% hydrogen - air mixture, gravity plays only a secondary role in determining the multidimensional structure of the flame with the stability and structure of the flame controlled primarily by the thermo-diffusive instability mechanism. However, in leaner hydrogen-air mixtures gravity becomes more important. Upward-propagating flames are highly curved and evolve into a bubble rising upwards in the tube. Downward-propagating flames are flat or even oscillate between structures with concave and convex curvatures. The zero-gravity flame shows only cellular structures. Cellular structures which are present in zero gravity can be suppressed by the effect of buoyancy for mixtures leaner than 11% hydrogen. These observations are explained on the basis of an interaction between the processes leading to buoyancy-induced Reyleigh-Taylor instability and the thermo-diffusive stability.