Local resistance loss of opener

     The local resistance loss of the opener is the energy loss caused by the eddy current phenomenon caused by the rapid change of the flow state of the airflow in the pipeline. For example, eddy currents can occur when a fluid passes through a bend or abruptly shrinks into an enlarged pipe, or when it passes through a valve or control element, or when two air streams merge, resulting in energy loss. When calculating pipeline resistance losses, local resistance losses are important. Because in most cases, the energy lost to overcome the local resistance is much larger than the energy lost to overcome the frictional resistance of the pipe wall. Pressure loss due to local resistance. Generally, the following formula can be used to calculate:

      The local resistance coefficient of the opener is obtained through experiments. To organize the experimental data, it can be listed in a table or drawn as a dark line, and an empirical formula can be obtained from the experimental data. In the design, it can be calculated according to the formula according to the conditions, or it can be directly obtained from the chart. It is more convenient to use the latter method for a boat. Several commonly used local drag coefficients are listed in 5-1.

       It should be pointed out that the frictional resistance loss and local resistance loss mentioned above are simply the loss when the air flows in the pipeline. In airflow transportation, the frictional resistance loss and local resistance loss of mixed air that uses air as a medium to convey objects in the pipeline are increased compared with the resistance loss of pure air flowing in the pipeline. It is known from the experiment that the increase of resistance loss has a certain relationship with the value of "matter-gas ratio" μ.

The correction weight of the mixed air is 37.5% higher than that of the pure air, so the resistance loss of the mixed air flowing in the pipe is 37.5% larger than the resistance loss of the pure air flowing in the pipe.

In the conveying system with air-flow tip, the ratio of matter to air in the cotton conveying pipeline is obviously different compared to the air ratio in the cotton returning pipeline. Therefore, when calculating the resistance loss, it can be carried out in stages, and the correction weight of the air can be obtained first according to the material-air ratio of each stage. Then substitute into the formula to calculate the resistance loss.