Flow%20Metering

Flow%20Metering - MAE 306 Mechanical Engineering...

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Unformatted text preview: MAE 306 Mechanical Engineering Laboratories II Lab # 1 Flow Metering MAE 306 Mechanical Engineering Laboratories II MECHANICAL & AEROSPACE ENGINEERING DEPARTMENT INSTRUCTOR: DR. C. M. TRAN Slide #1 MAE 306 Lab #1 Flow Metering Experiment Presentation Summary Objective Theory Apparatus Experimental procedure MAE 306 Mechanical Engineering Laboratories II MECHANICAL & AEROSPACE ENGINEERING DEPARTMENT INSTRUCTOR: DR. C. M. TRAN Slide #2 MAE 306 Lab #1 Flow Metering Objective Calibrate two types of flow meters: Venturi Rotameter MAE 306 Mechanical Engineering Laboratories II MECHANICAL & AEROSPACE ENGINEERING DEPARTMENT INSTRUCTOR: DR. C. M. TRAN Slide #3 MAE 306 Lab #1 Flow Metering Theory Venturi u1 p1 1 A 1 T1 A2 2 p2 T2 u2 An application of flow obstruction method, using pressure drop to indicate flow rate. Bernoulli Eq. Solving for velocity at 2 2 p1 u12 p2 u2 + = + 2( p1 - p2 ) u2 = = 1 2 2 2 2 Incompressible fluid 1 = 2 = From mass conservation ( m = 1 A1u1 = 2 A2u2 ) A2 u2 2 p1 A1 = p2 + u2 + 2 2 MAE 306 Mechanical Engineering Laboratories II 2 2 p 1 - A2 A 1 A2 2 1 - A 1 MECHANICAL & AEROSPACE ENGINEERING DEPARTMENT INSTRUCTOR: DR. C. M. TRAN Slide #4 MAE 306 Lab #1 Flow Metering Theory Venturi u1 p1 1 A 1 T1 A2 2 p2 T2 u2 Expressing as flowrate Q = A2 u 2 Qideal = A2 2 p A2 2 1 - A 1 The flow is viscous and therefore will have frictional losses so a discharge coefficient is defined C= Qactual Qideal MAE 306 Mechanical Engineering Laboratories II MECHANICAL & AEROSPACE ENGINEERING DEPARTMENT INSTRUCTOR: DR. C. M. TRAN Slide #5 MAE 306 Lab #1 Flow Metering Theory Rotameter An application of drag effect using the position of float to indicate flow rate. As the flow moves up the rotameter the area increases causing a decrease in fluid velocity (continuity eq.) Drag (velocity dependent), buoyancy, and gravitational forces cause the bob to maintain a position under a steady flow MAE 306 Mechanical Engineering Laboratories II MECHANICAL & AEROSPACE ENGINEERING DEPARTMENT INSTRUCTOR: DR. C. M. TRAN Slide #6 MAE 306 Lab #1 Flow Metering Apparatus Captured volume method After passing through a flow meter the fluid is captured and measured in a bulk tank Each line represents 0.069 gal. The time taken to fill a specified number of lines is measured and recorded. The temperature of the fluid is measured and recorded. The captured flow can now be compared to the flow meter reading. Thermocouple From flow meter The volume flow rate is calculated as Qexp # lines 0.069 gal 0.1337 ft 3 = time line gal MAE 306 Mechanical Engineering Laboratories II MECHANICAL & AEROSPACE ENGINEERING DEPARTMENT INSTRUCTOR: DR. C. M. TRAN Slide #7 MAE 306 Lab #1 Flow Metering Experimental Procedure Rotameter 1. Set up the rotameter on the flow bench. 1. Open the supply valve completely. Use the rotameter inlet valve to vary the flow. At each flow setting: a. Use the captured-volume method to determine the experimental flow rate Qexp,current. b. Record the bob height. c. Record the water temperature. MAE 306 Mechanical Engineering Laboratories II MECHANICAL & AEROSPACE ENGINEERING DEPARTMENT INSTRUCTOR: DR. C. M. TRAN Slide #8 MAE 306 Lab #1 Flow Metering Experimental Procedure Rotameter 1. Standard condition is where specific gravity, SG = 1. Correct the experimental flow rate at the current condition to standard condition by a. From the water temperature, look up water density using the given chart, then calculate the specific gravity. MAE 306 Mechanical Engineering Laboratories II MECHANICAL & AEROSPACE ENGINEERING DEPARTMENT INSTRUCTOR: DR. C. M. TRAN Slide #9 MAE 306 Lab #1 Flow Metering Experimental Procedure Rotameter 1. Cont. a. From the specific gravity correction curve for liquid, look up the correction factor CF. b. Calculate the experimental flow rate at standard condition using Q Qexp , SG =1 = exp ,current CF 1. Plot Qexp,SG=1 vs. bob height. 1. From the manufacturer's calibration curve, select 6 appropriate data points. On the same graph in (4), plot Qman,SG=1 vs. bob height. MAE 306 Mechanical Engineering Laboratories II MECHANICAL & AEROSPACE ENGINEERING DEPARTMENT INSTRUCTOR: DR. C. M. TRAN Slide #10 MAE 306 Lab #1 Flow Metering Experimental Procedure Venturi 1. Set up the venturi on the flow bench. 1. Use the supply valve to vary the flow. At each flow setting, a) Use the captured-volume method to determine the experimental flow rate Qexp. b) Record the pressure drop p. c) Record the water temperature. 1. Plot Qexp vs. p. 1. From the water temperature, look up water density using the given chart. State which temperature you use beginning, average, or end. MAE 306 Mechanical Engineering Laboratories II MECHANICAL & AEROSPACE ENGINEERING DEPARTMENT INSTRUCTOR: DR. C. M. TRAN Slide #11 MAE 306 Lab #1 Flow Metering Experimental Procedure Venturi 1. Given throat entrance diameter D1 = 0.248 in., and throat diameter D2 = 0.125 in., calculate the ideal flow rate using Qideal = A2 2 p A2 2 1 - A 1 where A1 and A2 are entrance and throat areas. 1. Calculate the discharge coefficient using C= Qexp Qideal 1. Plot Qideal vs.p on the same graph in (3). MAE 306 Mechanical Engineering Laboratories II MECHANICAL & AEROSPACE ENGINEERING DEPARTMENT INSTRUCTOR: DR. C. M. TRAN Slide #12 MAE 306 Lab #1 Flow Metering QUESTIONS ? MAE 306 Mechanical Engineering Laboratories II MECHANICAL & AEROSPACE ENGINEERING DEPARTMENT INSTRUCTOR: DR. C. M. TRAN Slide #13 ...
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This note was uploaded on 05/05/2010 for the course MAE 306 taught by Professor Gilbert during the Spring '08 term at N.C. State.

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