1. Radial Pump Impeller Design (Example)

2. Design a rotor(impeller) of a radial water pump for the following given values Q = 300 m3/h (0.0833 m3/s) H = 50 m n = 1450 rpm

3. The Specific speed for the pump is calculated from the following formula for the given values • After finding the specific speed the shape of the impeller can be decided using the following table. • The specific speed is in the radial type pump range

4. The shaft Power is given as: • The overall efficiency, ηo, for a single stage, single entry, radial pump can be read from the figure below to be ηo = 0.85. • The pump power becomes,

5. (Source: Centrifugal Pumps, Johann Friedrich Gülich, 2nded)

6. Shaft diameter can be found using the following formula • The torque can be calculated as it follows: • The allowable shear stress for most of the shafts is in the range between 40 -60 N/mm2.Thus the shaft diameter becomes: • The hub diameter, dh = 1.1 to 1.3 ds

7. The eye diameter (D1) can be calculated by assuming inlet number . The radial velocity at the inlet is given by: • The volume flow rate at the suction end is given by: • Calculating for the eye diameter, • The volumetric efficiency is given by:

8. The inlet number can be found from the following table. Guidelines to choose ε

9. From the table, • Thus, • Another option to estimate the value of inlet number is to use the formula by Pfleiderer, • Thus, D1 becomes,

10. The outer diameter D2can be calculated using: • The head coefficient (ψ) The head coefficient for different type of pumps is given below.

11. Choosing ψ = 1, • The specific diameter (δ) The specific diameter becomes,

12. D2 becomes, • The specific diameter is plotted in the following diagram for various specific speeds, • From the table, δ = 6.5. • Thus the outer diameter can be taken to be D2 = 0.4m

13. Cordier Diagram

14. Blade width b1 • The Blade width at the outlet b2 • C2m can be found from figure below.

16. Blade angle β0 • Blade angle β2can be estimated from the previous figure. • Number of blades