Fluid Rate

Objectives TLW analyze rate in fluid systems (TEKS 8.A) TLW measure, verify, and analyze rate in fluid systems (TEKS 8.B)

Intro Fluids – liquids or gases Name 3 examples of how each of the above fluids flow (move) For example – air to your lungs or a river

Engagement Activities Float, Float, Float Your Boat demo Up, Up, and Away demo

Flow Rates Volume Flow Rate Mass Flow Rate Volume Flow Rate = change in Volume∆V (V f – V i ) time interval ∆t (t f – t i ) Mass Flow Rate = change in mass ∆m (m f – m i ) time interval ∆t (t f – t i ). V = M =.

Flow Rates - shorthand Volume Flow Rate = Volume time per V = v/t. Mass Flow Rate =time M = m/ t. Mass per

Calculations – Group Practice The space shuttle’s main engine burns a mixture of hydrogen and oxygen as its fuel. The shuttle’s external tank stores liquid hydrogen and liquid oxygen in separate tanks. The liquid oxygen tank holds 143,000 gallons which supplies the main engine for 8.5 minutes. What is the volume flow rate?

Calculations – Group Practice If the space shuttle’s external hydrogen tank holds 226,000 pounds of liquid H 2 that are also consumed during the first 8.5 minutes of flight, what is the mass flow rate?

Measuring Flow Rates Volume Flow Rate = Cross-sectional area Fluid speed (flow rate) X V = A v. Mass Flow Rate = Fluid density Fluid speed (flow rate) X m =  A v. Cross-sectional area X

Calculations – Group Practice During liftoff, a rocket’s liquid oxygen flows from the storage to the main engine. If it flows through a discharge pipe with a 17 inch diameter, what is the speed of the liquid oxygen in feet per sec? (use volume flow rate from before. Also there are 231 cubic inches per gallon)

Calculations – Group Practice Miss Hunt’s PoT class has been asked by NASA to design a discharge pipe for the space shuttle’s liquid hydrogen tank. They want the hydrogen fluid speed to be eight times the oxygen speed. What diameter pipe should we use in the design?. (weight density of H 2 is 4.42 lb/ft 3 )

Factors Influencing Flow Rate Material’s viscosity (liquids) Friction (liquids) Air resistance (gases) Pressure (liquids and gases)

Bernoulli’s Principle As the speed of a fluid increases, the pressure inside of the fluid – or exerted by it - decreases

Bernoulli’s Principle

Fluid Flow Laminar Flow – smooth Turbulent Flow – mixes more may cause erosion in pipes if too much

Independent Practice Handout adapted from Physics in Context textbook Questions 1 – 9 on pages 146 – 148