Investigation of pressure loss in a circular pipe under ultrasonic waves released along main stream flow

Recently, ultrasound was discovered to have great potential in enhancing heat transfer from thermal systems., However, there is little information of the flow resistance, induced by its waves. Therefore, this research investigates the pressure loss of turbulent water flow in a circular pipe disturbed by 25 kHz ultrasound at the Reynolds number of 10,000, 12,500, 15,000, 17,500, 20,000, 22,500, and 25,000. The size of test section was modeled in accordance with the power plant’s condenser and the flow had been verified by the comparison of friction factor with theory. The maximum and minimum differences were 9.79 and 0.33%, respectively, confirming the reliability of the test setup. In this study, ultrasound was released along the mainstream flow from 3 and 15 transducers, installed upstream of the pipe. The results confirmed that the ultrasound was slightly affected on the friction loss of turbulent pipe flow. The average increase of pressure loss was 0.077% and 0.833% by the waves when they were emitted from 3 and 15 transducers, respectively. With very low inducement of flow resistance, ultrasound can be accounted as one of the most promising techniques for heat transfer enhancement, applicable to many thermal systems such as condensers, in the future.