气液两相流基础概念
国际巨星排行榜Two pha flow fundamental (vapor-liquid, gas-liquid) ● Static quality, is the fraction of vapor in a saturated mixture. No flow or clod system.
g
g g st g l g g l l M A x M M A A ρρρ==++
● Flow quality, or vapor quality in two pha flow, it’s convenient to u flow quality instead of the static quality. Open system. g g g g g l g g g l l l m u A x m m u A u A ρρρ==++
● Thermodynamic equilibrium quality (thermodynamic vapor quality). It can be ud only for single-component mixtures (e.g. water with steam), and can take values x<0 (for sub-cooled fluids) and x>1 (for super-saturated vapours)
m l g l
外贸尾单服装批发h h x h h -=- All of the quality above coincide if the two phas are at thermodynamic equilib
rium (i.e. HEM). Once taking subcooled boiling model into consideration, the thermodynamic equilibrium quality is not equal with flow quality.
● The void fraction
i. T he fraction of the channel volume that is occupied by the gas pha. This void fraction is known as the volumetric void fraction.
g
V g l V V V α=+
ii. T he fraction of the channel cross-ctional area that is occupied by the gas pha. This void fraction is known as the cross-ctional void fraction. It is the widely utilized void fraction definition.
, g
A g l A or A A αα=+
iii. T he local void fraction refers to that at a one single point or very small volume. Therefore it takes the values of 1 or 0.中文翻译英语
● Pha velocity and superficial velocity
Superficial velocity is a hypothetical flow velocity calculated as if the given pha or fluid were the only one flowing or prent in a given cross ctional area. The velocity of the given pha is calculated as if the cond pha was ignored. In engineering of multipha flows and flows in porous media, superficial velocity (j ) is commonly ud, becau it is the value which is unambiguous, while real velocity is often spatially dependent and subject to many assumptions.
e
,(1)(1)phas pha pha pha pha g g l l
l g l g
Q Q u j A A
j u j u j j j u u αααα====-=+=-+， ● Drift velocity of gas pha with respect to the volumetric center of the mixture: gj g V u j =-
求孔隙率模型
生活语录
● Homogeneous equilibrium model (HEM)王子博
111()g s反腐倡廉演讲稿
x x αρρ=-+ The velocity ratio is a concept utilized in parated flow types. Introducing the idea
into the HEM void fraction equation results in
111()g s
x S x αρρ=-+ Where Slip ratio, or velocity ratio is the ratio of the velocity of the vapor pha to the velocity of the liquid pha. (g
l u S u =)
绿萝浇水With slip void fraction model, the cross-ctional void fraction and volumetric void fraction is derived:1
(1)V S α
熊孩子为什么叫熊孩子
ααα=+-
