# Calculate and compare the efficiency of the two turbines of Prob. 14123. They should be the same

## Question:

Calculate and compare the efficiency of the two turbines of Prob. 14–123. They should be the same since we are assuming dynamic similarity. However, the larger turbine will actually be slightly more efficient than the smaller turbine. Use the Moody efficiency correction equation to predict the actual expected efficiency of the new turbine. Discuss.

**Data from Prob. 14–123.**

A group of engineers is designing a new hydroturbine by scaling up an existing one. The existing turbine (turbine A) has diameter D_{A} = 1.50 m, and spins at ṅ_{A} = 150 rpm. At its best efficiency point, V̇_{A} = 162 m^{3}/s, H_{A} = 90.0 m of water, and bhp_{A} = 132 MW. The new turbine (turbine B) will spin at 105 rpm, and its net head will be H_{B} = 95 m. Calculate the diameter of the new turbine such that it operates most efficiently, and calculate V̇_{B} and bhp_{B}.

## Step by Step Answer:

**Related Book For**

## Fluid Mechanics Fundamentals And Applications

**ISBN:** 9780073380322

3rd Edition

**Authors:** Yunus Cengel, John Cimbala