Propeller Design Report (Based on Resistance Report of HW#7)

OCEN 402 HW # 9

Propeller design Report (Based on Resistance Report of HW#7)

Description

In the previous (HW#7) HW, we have computed total resistance and EHP at three difference drafts as a function of the velocity of the ship. In this HW, we use NavCad to design the propeller.

1. Using NAVCAD (propeller analysis, free run version and try different design of propellers described below) to determine the thrust force, brake power, efficiency of the propeller as a function of the ship speed.

2. We adopt the main engineering with the brake power, PB = 4,000 HP, its rotation velocity n = 100

RMP or 90 RMP, the efficiency of the shaft hshaft = 0.97 and no gear box is used (thus the gear ratio is 1.0 and its efficiency is 1.0). What is the trial speed the ship can reach for each design case?

3. What is the cavitation condition for each propeller (whether or not it passes the cavitation requirement)?

4. What is the optimal design of the propeller in your opinion? Please present your reasoning

Assignment & Loading Conditions

Group 1&12 2 3 4 5 6 7 8 9 10 11 Cb 0.6 0.6 0.65 0.65 0.7 0.7 0.75 0.75 0.8 0.8 0.8 Draft Normal N N N N N N N N N N Over draft +5% +7% +5% +7% +5% +7% +5% +7% +5% +7% +10% Light draft -5% -7% -5% -7% -5% -7% -5% -7% -5% -7% -10%

Detailed work and report outline

1. The range of the ship velocity should cover a range from 12 – 18 knots. For a ship having a smaller block coefficient, you may slide the range towards the upper end and a ship having a greater block coefficient, you should slide it to the lower end.

2. Using Series B propellers (3 blades A = 0.50 and 0.60 and 4 blades, and A = 0.55 and 0.70, D = 13, 15, 16, and 17 ft and choose the best pitch for each propeller, e.g. using the B-series diagrams) and hull-propeller interaction coefficients (Series 60) to determine the Thrust force and power.

3. Preparing a report which contains the matrix of the design cases (different combination of propellers, rotation velocity and diameters), the optimal designs of the propellers given the three load conditions. You should present a discussion about your conclusion about the optimal design.