# Lab report

Abstract……………………………………………………………………………………………2

Introduction………………………………………………………………………………………..2

Background………………………………………………………………………………..2

Objectives…………………………………………………………………………………2

Scope………………………………………………………………………………………3

Theory review……………………………………………………………………………………..3

Design of report…………………………………………………………………………………...5

Procedures…………………………………………………………………………………………5

Results……………………………………………………………………………………………..6

Discussion…………………………………………………………………………………………6

Conclusion………………………………………………………………………………………...7

Reference……………………………………………………………………………………….....7

Appendix…………………………………………………………………………………………..7

ABSTRACT

This experiment introduces the use of dimensionless analysis and conventionally analytical method to survey the performance of centrifugal pump. The end of this experiment points out the benefit of using the “new” method to the conventional in most practical problem, especially in the survey of turbo-machine. Also, through this experiment, students know some basic indexes to assess the efficiency of pumps used. We will that for the specific fan conducting this experiment, the best efficiency point occurs at CQ = 0.2, the specific speed NS ~1.23.

INTRODUCTION

Background

A fan is a turbo-machine in which work is done to increase the total pressure of the fluid leaving the device. This is achieved by a rotor or impeller, which is driven by an external source of power to move a row of blades so as to impart energy to the fluid.

A centrifugal fan, the focus of this experiment, consists basically of three components: an air inlet duct, an impeller and a volute casing. The inlet duct conducts the fluid (in this case, it is air) into the impeller. The air then passes through a rotating row of blades resulting in the increase in pressure and velocity. The high velocity of the air in the exit of the impeller is converted into additional pressure rise by velocity reduction in the volute which acts basically as a

References: 1. http://en.wikipedia.org/wiki/Volute_(pump) 2. B.R Muson, D.F Young and T.H Okiishi, Fundamentals of Fluid Mechanics, Wiley, New York (2010) - Chapter 7 and 12. APPENDIX 1. The Buckingham π theorem: If an equation involving k variables is dimensionally homogeneous, it can be reduced to a relationship among k-r independent dimensionless products, where r is the minimum number of reference dimensions required to describe the variables. 2. Centrifugal fan and volute image: 3. Approximated Reynolds numbers of fan at 2103 RPM and almost the same air’s condition.( Our real condition: T = 27.80 oC, Patm = 758.79 mmHg, ρatm = 1.169 kg/m3). Meanwhile, at T = 300K, P = 100kPa, ρ= 1.161 kg/m3, μ = 18.6 x 10-6 Pa.s. We have ω ~ 220 rad/s, D ~ 0.140 m. Re = 2.692x105.