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渣漿泵水力學(xué)與流體力學(xué)基礎(chǔ)知識

第一節(jié) 流體的主要力學(xué)性質(zhì)
一、密度ρ

單位體積就體所具有的質(zhì)量標(biāo)為流體的密度，以ρ表示。水的密度見表1-1及表1 -2。
對均質(zhì)流體:                ρ=M/V
式中  ρ----流體的密度， kg/m3;
      M----流體的質(zhì)量，kg;

V-----流體的體積，m3。

二、重度γ

單位體積流體所具有的重量稱為流體的重度，以γ表示。

對均質(zhì)流體:            γ=G/V
式中  y----流體的重度，N/m3; (工程制kgf/m3 );
      G----流體的重量，N (工程制 kgf);

V----流體的體積， m3;
密度和重度的關(guān)系:因為重量是質(zhì)量和重力加速度的乘積，即:
                      G=Mg

代入式(1-2):               γ=Mg/V=pg  

式中  g----重力加速度，m/s2, g=9. 807m/s2。

對于4°C左右的水，它的密度ρ= 1000kg/m3，它的重度γ = 9807N/m3 (工程制: 100kgf/m3 )。
三、流體的壓縮性和熱脹性

1. 流體的壓縮性

流體受壓，體積縮小，密度增大的性質(zhì)，稱為流體的壓縮性。流體隨壓力的增減變化很小，可視為不變，稱為不可壓縮流體，如液體為不可壓縮流體。而氣體的體積、密度隨壓力增減有顯著的變化，稱可壓縮流體。
2.流體的熱脹性

流體受熱后，體積膨脹，密度減小的性質(zhì)，稱為流體的熱脹性。渣漿泵

Basic knowledge of hydrodynamics and hydrodynamics of slurry pump

Section I main mechanical properties of fluid

I. density ρ

The mass per unit volume is the density of the fluid, expressed as ρ. See Table 1-1 and table 1-2 for the density of water.

For homogeneous fluid: ρ = m / V

Where ρ - density of fluid, kg / m3;

M - mass of fluid, kg;

V -- volume of fluid, m3.

II. Severe γ

The weight of a unit volume of fluid is called the gravity of the fluid, expressed in gamma.

For homogeneous fluid: γ = g / V

Where y is the density of fluid, N / m3; (Engineering kgf / m3);

G - weight of fluid, n (Engineering KGF);

V - volume of fluid, m3;

Density and gravity: because weight is the product of mass and acceleration of gravity, that is:

G=Mg

Substituting formula (1-2): γ = mg / v = PG

Where, G ---- acceleration of gravity, M / S2, g = 9.807m/s2.

For water at about 4 ° C, its density ρ = 1000kg / m3, its gravity γ = 9807n / m3 (Engineering System: 100kgf / m3).

III. compressibility and thermal expansion of fluid

1. Compressibility of fluid

The compressibility of a fluid is the property that the fluid is compressed, the volume is reduced, and the density is increased. The change of fluid with the increase or decrease of pressure is very small, which can be regarded as constant. It is called incompressible fluid, for example, liquid is incompressible fluid. However, the volume and density of gas change significantly with the increase or decrease of pressure, which is called compressible fluid.

2. Thermal expansion of fluid

After the fluid is heated, its volume expands and its density decreases, which is called the thermal expansion of the fluid.