各種壓力的說明Pressure instructions

1、大氣壓：地球表面上的空氣柱因重力而產生的壓力。它和所處的海拔高度、緯度及氣象狀況有關。

2、差壓（壓差）：兩個壓力之間的相對差值。

3、絕對壓力：介質（液體、氣體或蒸汽）所處空間的所有壓力。絕對壓力是相對零壓力而言之壓力。

4、表壓力（相對壓力）：如果絕對壓力和大氣壓的差值是一個正值，那麼這個正值就是表壓力，即表壓力=絕對壓力-大氣壓＞0。

5、負壓（真空表壓力）：和“表壓力“相對應，如果絕對壓力和大氣壓的差值是一個負值，那麼這個負值就是負壓力，即負壓力=絕對壓力-大氣壓＜0。

6、靜態壓力：一般理解為“不隨時間變化的壓力，或者是隨時間變化較緩慢的壓力，即在流體中不受流速影響而測得的表壓力值”。

7、動態壓力：和“靜態壓力”相對應，“隨時間快速變化的壓力，即動壓是指單位體積的流體所具有的動能大小。”通常用1/2ρν2計算。式中ρ為流體密度；v為流體運動速度。”

     1. the pressure generated by the column of air in the atmospheric pressure: the Earth's surface due to gravity. In which the altitude, latitude and weather conditions.

      2. the differential pressure (pressure): the relative difference between the two pressure.

3. the absolute pressure: the space in which all the pressure of the medium (liquid, gas or steam). The absolute pressure is the pressure relative zero pressure.

4. the gauge pressure (relative pressure): the difference between the absolute pressure and atmospheric pressure is a positive, then the positive gauge pressure, ie gauge pressure = absolute pressure - atmospheric pressure> 0.

5. Negative pressure (vacuum gauge pressure): "gauge pressure" corresponds to the difference between the absolute pressure and atmospheric pressure is a negative, this negative is a negative pressure, negative pressure = absolute pressure - atmospheric pressure <0.

6. the static pressure: Generally understood as the pressure does not change over time, or is relatively slow time-varying pressure in the fluid from the flow rate affect the value of the measured gauge pressure.

7. the dynamic pressure: static pressure "corresponds to" with a time of rapid changes in pressure, that is, dynamic pressure refers to the size of the kinetic energy of per unit volume of fluid usually 1/2ρν2 calculation. Where ρ is the fluid density; v is the fluid velocity. "