Fluid Statics and Manometry

docx

School

California State University, Long Beach *

*We aren’t endorsed by this school

Course

335

Subject

Mechanical Engineering

Date

Apr 3, 2024

Type

docx

Pages

Uploaded by Ryan_osborn1

Energy Losses in Pipe Bends CE 336 Department of CECEM Individual Report Group Members: Major Ryan Osborn ME Date: Spring 2018

Purpose The goal of this experiment was to demonstrate the behavior of liquids under hydrostatic conditions. Introduction/Theory Fluids can either be in motion or in a state known as hydrostatic, which essentially means still. Under hydrostatic conditions fluids experience pressure, which can be found via calculation after observing one of the following: 1. Direct measurement with a ruler 2. A Vernier hook and point device 3. A manometer Due to capillary rise there was a meniscus in the manometers. To get an accurate reading students had to measure heights from the bottom of the meniscus. Equipment  F1-29 Armfield Apparatus (see Figure 1 below)

Figure 1 : F1-29 Armfield Apparatus  A reservoir (2)  U-tube manometer  3 fixed tubes  Inclined manometer  Vernier hook and point scale Procedure 1. Measure height of water in reservoir using attached scale 2. Measure height of water in reservoir using attached Vernier scale 3. Measure height of water in u-tube, fixed tubes, and inclined manometer set at 90º using their attached markings 4. Adjust inclined manometer to 60˚ and measure height again 5. Adjust inclined manometer to 30˚ and measure height again 6. Apply pressure to reservoir and measure height change 7. Apply vacuum to reservoir and measure height change Data Surface Liquid Level (mm) Vertical Height (mm) Reservoir 123.2±0.1 X U-tube (Left/Right) 117.2 116.2 Fixed Tubes 117. 5 117 115. 9 116. 9 Inclined Tube at 60˚ 142 144 123.84 Inclined Tube at 30˚ 304 308 153.4

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

Table 1 : Manometer Heights Pressure change in reservoir Level change in the reservoir ∆h (mm) Pressure change ∆P (kN/m 2 ) Increased Pressure -103.5 1015 Reduced Pressure 86 -843.7 Table 2 : Height change in reservoir due to pressure Sample Calculations ∆ P =− ρg ∆h =− ( 1000 kg m 3 ∗ 9.81 m s 2 ∗− .1035 m ) ∆ P = 1015 kN m 2 Vertical height 144 + 142 2 sin ( 60 ) = 123.84 mm

Discussion Theoretically these measurements should all be identical. However, parallax combined with capillary rise can cause two readings of the same liquid to appear to be different. See figure 2 below for a visual representation of how this effect can cause a false reading. Figure 2 : Meniscus and Parallax potential false reading Additionally, the discrepancy in the height calculation of the inclined manometer can be attributed to the point of rotation. Since the point of rotation is about 40mm below the starting level of the liquid, when the inclined manometer rotates it brings the bottom point, where the liquid enters, below the starting point of the other fixed tubes. This is what causes the high value in the calculated height. To correct this students took the measured length and subtracted ( 40 sin ( 60 ) − 40 )mm for the 60˚

incline and ( 40 sin ( 30 ) − 40 )mm for the 30˚ incline. When these numbers were subtracted from their respective inclines the corrected values became 117.7mm and 113.4mm, which are far closer to the expected values. Conclusion Increasing the pressure in any of the tubes causes the liquid level in said tube to decrease thus increasing the height of liquid in the other tubes and vise-versa for a decrease in pressure. Furthermore, the meniscus and parallax effects make it difficult to read the heights of liquids in smaller tubes. In fact, the smaller the tube the more pronounced the effects were thus raising the difficulty in obtaining an accurate measurement. In the end it was found that using eyesight to measure the heights of fluid can be extremely difficult to do and results in a high level of error.

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version