RT - Journal Article T1 - Experimental study of scale effect and immersion ratio on the performance characteristics of a surface piercing propeller JF - Marine-Engineering YR - 2022 JO - Marine-Engineering VO - 18 IS - 35 UR - http://marine-eng.ir/article-1-943-en.html SP - 129 EP - 140 K1 - Surface piercing propeller K1 - Experimental study K1 - Scale effect K1 - Wall effect K1 - Immersion ratio AB - In this paper, the effect of scaling on the accuracy of experimental results obtained from water tunnels was investigated. Experimental tests were defined for three surface piercing propeller with similar geometry and diameters of 0.132 - 0.125 and 0.140 m. Thrust coefficients in different Immersion ratios are compatible with each other, the torque coefficient of propeller with a diameter of 0.140 does not correspond well with two propeller of 0.125 and 0.132. As the immersion ratio increases, the obstruction ratio increases, and the propeller torque with a diameter of 0.140 decreases compared to the other two propellers. Increasing the immersion ratio increases the torque and thrust in all three propellers; However, due to the effect of the obstruction ratio, the increase in torque in the immersion ratios is 0.40 to 0.70 less than the other two propellers. Also, with increasing the immersion ratio, the efficiency decreases and the highest efficiency for all three propellers is obtained in the immersion ratio of 0.40. As the immersion ratio increases in all three propellers, the critical advance coefficient decreases. LA eng UL http://marine-eng.ir/article-1-943-en.html M3 ER -