Hot Wire Anemometer 192333

FLUID FLOW MEASUREMENT

INTRODUCTION  FLUID FLOW IS UBIQUITOUS !!  IT IS ESSENTIAL TO MEASURE FLOW PROPERTIES.  MAJOR CATEGORIES OF FLUID FLOW

LAMINAR FLOW 2. TURBULENT FLOW • MOST PRACTICAL FLOWS ARE TURBULENT . HENCE EQUALLY IMPORTANT TO MEASURE TURBULENT FLUCTUATIONS. • MANY METHODS TO MEASURE FLOW VELOCITY FOR EXAMPLE –PITOT TUBE 1.

CHARACTERISTICS OF IDEAL INSTRUMENT TO MEASURE VELOCITY FLUCTUATIONS  GOOD SIGNAL SENSITIVITY : Measurable change in      

output for small changes in velocity. HIGH FREQUENCY RESPONSE : to accurately follow transients without any time lag . WIDE VELOCITY RANGE CREATE MINIMAL FLOW DISTURBANCE LOW COST HIGH ACCURACY EASY TO USE

HOT WIRE ANEMOMETER  INTRUSIVE TECHNIQUE  MEASUREMENT OF INSTANTANEOUS VELOCITIES

AND TEMPERATURE AT A POINT IN THE FLOW.  HOT WIRE ANEMOMETER NECESSARY TO CARRY OUT FUNDAMENTAL TURBULENT STUDIES.  HOT WIRE ANEMOMETER IS AN IDEAL TOOL FOR MEASUREMENT OF VELOCITY FLUCTUATIONS IN TIME DOMAIN IN TURBULENT FLOWS.

HOT WIRE ANEMOMETER

HOT WIRE ANEMOMETER  USED TO MEASURE FLUID VELOCITY BY

MEASURING HEAT LOSS BY CONVECTION FROM A VERY FINE WIRE WHICH IS EXPOSED TO FLUID STREAM .  THE WIRE IS ELECTRICALLY HEATED BY ING AN ELECTRICAL CURRENT THROUGH IT.  WHEN THE HEATED WIRE IS COOLED BY A FLUID STREAM , ITS ELECTRICAL RESISTANCE DECREASES.