scholarly journals Liquid-surface entrainment induced by shocked air stream

Shock Waves ◽  
2018 ◽  
Vol 29 (2) ◽  
pp. 361-364
Author(s):  
V. Rodriguez ◽  
G. Jourdan ◽  
A. Marty ◽  
A. Allou ◽  
J.-D. Parisse
Keyword(s):  
Liquid Surface ◽  
Air Stream

scholarly journals DEMONSTRATION TASKS OF LIQUID AND GAS PROPERTIES AND THEIR RATIONALE SENSE

2010 ◽  
Vol 7 (1) ◽  
pp. 29-37
Author(s):  
Violeta Šlekienė ◽  
Loreta Ragulienė
Keyword(s):  
Gas Flow ◽  
Liquid Surface ◽  
Flow Speed ◽  
Pressure Reduction ◽  
Physics Teaching ◽  
Liquid Surface Tension ◽  
Air Stream ◽  
Logical Sense ◽  
Physical Phenomena ◽  
Gas Properties

The article reveals the importance of demonstration tasks in physics teaching in secondary schools. Four demonstration of the liquid and gas properties are presented and analyzed. They are: Pressure dependence of gas flow speed; Pressure reduction in air-stream; Wing lift; Liquid surface tension. Reasoning schemes for giving a logical sense to these physics demo tasks are developed. The proposed reasoning schemes reach to activate students' thinking, understanding the demonstrations during the observed physical phenomena, i.e. help students to: understand the nature of the demo task, determine cause - effect relationships and dependencies, compare conditions and findings, summarize the results, do conclusions. Such using of demonstration tasks is useful to both of teacher and pupil: teacher controls the content of teaching and a learning of pupils, pupils - are focused to self-activities, encouraged to think, analyze, summarize and do conclusions. Key words: physics teaching, demonstration task, liquid and gas properties, reasoning schemes.

Wind-generated waves in thin liquid films

1966 ◽  
Vol 26 (2) ◽  
pp. 369-392 ◽  
Author(s):  
Alex D. D. Craik
Keyword(s):  
Tangential Stress ◽  
Liquid Surface ◽  
Stress Component ◽  
Liquid Films ◽  
Thin Liquid Films ◽  
Air Interface ◽  
Water Films ◽  
Air Stream ◽  
Joint Influence ◽  
Small Disturbances

In the presence of an air stream, a uniform liquid film on a horizontal flat plate may be unstable to small disturbances, and waves may arise. In this paper the hydrodynamic stability of thin liquid films is examined both experimentally and theoretically.The experiments concern water films thinner than those which have been examined in the past. It is found that, when the film thickness is sufficiently small, a previously unknown type of instability occurs. The theoretical analysis explains this surprising phenomenon.Due to interaction of the mean airflow and small disturbances of the liquid-air interface, normal and tangential stress perturbations are produced at the liquid surface. It is shown that small wave-like disturbances become unstable when the joint influence of the component of normal stress in phase with the wave elevation and the component of tangential stress in phase with the wave slope is sufficient to overcome the ‘stiffness’ of the liquid surface due to gravity and surface tension. It is found that the destabilizing role of the tangential stress component is dominant for very thin films, and that instability may occur whatever the velocity of the air stream, provided the film is made sufficiently thin.

Pollutant emission from a heat station supplied with agriculture biomass and wood pellet mixture

2012 ◽  
Vol 33 (2) ◽  
pp. 231-242 ◽  
Author(s):  
Marek Juszczak ◽  
Katarzyna Lossy
Keyword(s):  
Carbon Monoxide ◽  
Pollutant Emission ◽  
Heat Output ◽  
Wood Pellets ◽  
Wood Pellet ◽  
Carbon Monoxide Concentration ◽  
Heat Efficiency ◽  
Air Stream ◽  
Fuel Mixtures ◽  
Lower Carbon

Pollutant emission from a heat station supplied with agriculture biomass and wood pellet mixtureTests for combustion of hay and sunflower husk pellets mixed with wood pellets were performed in a horizontal-feed as well as under-feed (retort) wood pellet furnace installed in boilers with a nominal heat output of 15 and 20 kW, located in a heat station. During the combustion a slagging phenomenon was observed in the furnaces. In order to lower the temperature in the furnace, fuel feeding rate was reduced with unaltered air stream rate. The higher the proportion of wood pellets in the mixture the lower carbon monoxide concentration. The following results of carbon monoxide concentration (in mg/m3presented for 10% O2content in flue gas) for different furnaces and fuel mixtures (proportion in wt%) were obtained: horizontal-feed furnace supplied with hay/wood: 0/100 - 326; 30/70 - 157; 50/50 - 301; 100/0 - 3300; horizontal-feed furnace supplied with sunflower husk/wood: 50/50 - 1062; 67/33 - 1721; 100/0 - 3775; under-feed (retort) furnace supplied with hay/wood: 0/100 - 90; 15/85 - 157; 30/70 - 135; 50/50 - 5179; under-feed furnace supplied with sunflower husk/wood: 67/33 - 2498; 100/0 - 3128. Boiler heat output and heat efficiency was low: 7 to 13 kW and about 55%, respectively, for the boiler with horizontal-feed furnace and 9 to 14 kW and 64%, respectively, for the boiler with under-feed furnace.

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