渣浆泵水力学与流体力学基础知识

第一节 流体的主要力学性质
一、密度ρ

单位体积就体所具有的质量标为流体的密度，以ρ表示。水的密度见表1-1及表1 -2。
对均质流体:                ρ=M/V
式中  ρ----流体的密度， kg/m3;
      M----流体的质量，kg;

V-----流体的体积，m3。

二、重度γ

单位体积流体所具有的重量称为流体的重度，以γ表示。

对均质流体:            γ=G/V
式中  y----流体的重度，N/m3; (工程制kgf/m3 );
      G----流体的重量，N (工程制 kgf);

V----流体的体积， m3;
密度和重度的关系:因为重量是质量和重力加速度的乘积，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。

对于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、流体的压缩性和热胀性

1. 流体的压缩性

流体受压，体积缩小，密度增大的性质，称为流体的压缩性。流体随压力的增减变化很小，可视为不变，称为不可压缩流体，如液体为不可压缩流体。而气体的体积、密度随压力增减有显著的变化，称可压缩流体。
2.流体的热胀性

流体受热后，体积膨胀，密度减小的性质，称为流体的热胀性。渣浆泵

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.