Study on Evaluation Method of Flow Characteristics in Steady How Bench(8)-Momentum Distribution along to Radial Direction(2)

This paper is the eighth and last investigation on the methods of evaluating flow characteristics in a steady flow bench. In this study, the effect of tangential velocity distribution along the radial direction on the measured torque is quantitatively evaluated For this purpose, the effects of the evaluation center setting and axial velocity are at 4.50 B, 4.50 times of the bore position apart from the bottom of the head, and the 6.00 B downstream plane were investigated. The following conclusions were made. The distribution of tangential velocity in the radial direction increases as it goes downstream, and, regardless of the center setting, for valve angles below 21°, the best match for ideal distribution is at 4.50 B, but at 6.00 B for 26°. Also, at 6.00 B, it shows a parabolic shape. Below 16°, it is higher than the ideal distribution for all lifts, and sometimes it is above 21°. At the same time, the cumulative torque increases as it proceeds downstream, which best matches the ISM evaluation at 4.50 B when axial velocity is proportional to the tangential velocity, and is a cylinder-centric evaluation. Cumulative torque is often significantly higher than the ideal distribution at 6.00 B. Finally, regardless of the measuring plane, lift, and valve angle, the cumulative torque of up to a dimensionless radius of 0.4 is very small, and, practically, it has little effect on the final value. Furthermore, regardless of the center setting, it affects the final value when the radius is 0.6 or more, though the value when the radius is 0.8 plays a dominant role.