14-Practice Problems

# 14-Practice Problems - Chapter 14 Turbomachinery Problem...

This preview shows pages 1–3. Sign up to view the full content.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Chapter 14 Turbomachinery Problem 14.1 A propeller is to be selected for a light airplane with a mass of 1500 kg which will cruise at 100 m/s at an altitude where the density is 1 kg/m 3 The lift-to-drag ratio at cruise conditions is 30:1, and the engine rpm is 3500. The thrust coe g33- cient at maximum e g33 ciency is 0.03, and the maximum e g33 ciency is 60%. Find the diameter of the propeller, the advance ratio at maximum e g33 ciency, and the power output required by the engine. Solution At cruise conditions, the drag is equal to the thrust. g87 = g71 = g79g64 ( g79g64g71 ) = 1500 × 9 g61 81 g64 30 = 490 g61 5 N The thrust is given by g87 = g70 g87 g29g113 2 g71 4 490 g61 5 = 0 g61 03 × 1 × μ 3500 60 ¶ 2 g71 4 = 102 g61 1 g71 4 Solving for diameter g71 4 = 4 g61 805 g71 = 1 g61 48 m The advance ratio is g77 = g89 g114 g113g71 = 100 58 g61 3 × 1 g61 48 = 1 g61 16 125 126 CHAPTER 14. TURBOMACHINERY The power output is g83 = g87g89 g114 g20 = 490 g61 5 × 100 g61 6 = 81 g61 75 kW = 110 hp Problem 14.2 A pump delivers 0.25 m 3 /s of water against a head of 250 m at a rotational speed of 2000 rpm. Find the speci g31 c speed, and recommend the appropriate type of pump. Solution The speci g31 c speed of the pump is g113 g118 = g113g84 1 g64 2 ( g106 g4 g75 ) 3 g64 4 = 2000 60 × g61 25 1 g64 2 (9 g61 81 × 250) 3 g64 4 = 0 g61 048 From Fig. 14.14, a mixed g32 ow pump is recommended....
View Full Document

## This note was uploaded on 12/18/2011 for the course ECON 102 taught by Professor Drfcvvv during the Spring '11 term at Politechnika Wrocławska.

### Page1 / 6

14-Practice Problems - Chapter 14 Turbomachinery Problem...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online