The effects of gravity on wrinkled laminar flames
Laminar and turbulent conical Bunsen type flames were used. The study compares results from normal gravity with the burner in an up-right orientation (+g), the burner inverted (-g), and in microgravity ({mu}g) by using the NASA Lewis drop tower facility. The primary diagnostic is a laser schlieren system and some LDA measurements were taken for the +g condition to measure the flow field. The +g laminar flame experiences a large amount of instabilities and results in an unsteady flame tip; cause is torroidal vortex rolling up between products and stagnate surrounding air. Comparison between LDA measurements in reactants and schlieren images shows that velocity fluctuation are induced at the same frequency as the roll up vortices are formed. This pumping of the reactant stream by the product/air interface instability in the +g case is also observed in the turbulent flames. In the -g arrangement the product/air interface is stable so there is no large pumping of the flame tip. At low flow rates the -g flames have flattened tips, but at higher flow rates they become conical in shape. When both flames. appear conical, the -g flames are longer for the same flow rate. In {mu}g the larger instabilities in the flame no longer exist as the product/air interface is believed to become stable. The laminar flames in {mu}g still show small instabilities over the entire flame.
- Research Organization:
- Lawrence Berkeley Lab., CA (United States)
- Sponsoring Organization:
- National Aeronautics and Space Administration, Washington, DC (United States)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 10103669
- Report Number(s):
- LBL-32927; CONF-9210213-1; ON: DE93002572; CNN: Contract C-32000-R
- Resource Relation:
- Conference: 1992 Combustion Institute fall meeting of the western states section,Berkeley, CA (United States),12-13 Oct 1992; Other Information: PBD: Sep 1992
- Country of Publication:
- United States
- Language:
- English
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