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What are the main components of current losses

2022-05-10

In the process of drilling and exploration, we often encounter problems in fluid loss testing. The purpose of fluid loss testing is to test the internal friction force of the laminar bottom layer and the occurrence of momentum exchange such as fluid particle mixing and collision in the turbulent core area. additional resistance. In this way, we can better understand the geological structure.

 

Blenders and Mixers

 

Flow loss mainly includes airfoil loss and secondary flow loss, of which airfoil loss mainly includes the following five aspects:

 

1. Wave resistance loss of shock wave: When a supersonic zone appears in the cascade channel, a shock wave will be generated. When the airflow flows through the shock wave, the total pressure will drop, which is called shock wave loss.

 

2. Friction loss in the blade boundary layer: When the airflow flows through the blade cascade, a boundary layer will be formed on the surface of the blade cascade due to the viscous effect of the air. There is friction loss in the air flow in the boundary layer.

 

3. Boundary layer separation loss: During the process of airflow from the leading edge to the trailing edge of the airfoil, the pressure is constantly increasing. Under the action of the positive pressure gradient, the boundary layer may be separated, especially the shock wave attachment. Losses from boundary layer separation due to surface layer disturbance.

 

4. Eddy current loss in the wake: When the airflow flows from the blade back and the blade basin to the trailing edge of the airfoil, the boundary layers on both sides merge to form the wake of the blade, and the upper and lower surface boundary layers meet at the trailing edge. When , a vortex area will also be generated. Due to the viscous effect, the kinetic energy consumed by the vortex motion is converted into heat energy, which is the wake loss.

 

5. Mixing loss in wake and main flow area: Since the airflow velocity in the wake is small, but the airflow velocity in the main flow area is large, there is a large velocity gradient between the wake and the main flow area. When mixing the wake and the mainstream area, the speed should be uniform, and there will be losses in this mixing process.