CH 3 Energy and Power in Hyd Systems (Image Compression)

8/4/2019 CH 3 Energy and Power in Hyd Systems (Image Compression)

1/59

CH 3

ENERGY AND POWER INHYDRAULIC SYSTEMS


2/59

OBJECTIVES1. Differentiate between hydraulic energy and hydraulic power.2. Define the term efficiency

3. Desribe the operation of and air-to-hydraulic pressure booster.

4. Explain the conservation of energy law

5. Calculate fluid flow rates and velocities using the continuity equation

6. Evaluate the power delivered by a hydraulic cylinder7. Determine the speed of a hydraulic cylinder

8. Describe the differences between potential energy, pressure energy

and Kinetic Energy

9. Describe the operation of a hydraulic jack

10. Apply Bernoullis equation to determine energy transfer within a

hydraulic system.11. Understand the meaning of the terms elevation head, pressure head

velocity head.

12. Differentiate between the terms pump head, motor head and head loss.


3/59


4/59


5/59


6/59


7/59


8/59

NEWTONS SECOND LAW


9/59

This is when you REALLY want to say f**k Newton and his second law.


10/59


11/59


12/59

Zero accelerationConstant positive acceleration

with zero initial velocity

Increasing accelerationDecreasing acceleration


13/59

A car travels 35 miles in 45 minutes. What is its average velocity in miles per hour?

PRACTICE

v = S/ T = 35 MILES/43 MINUTES = .814 MILES /MIN

.814 (MILES/MIN)(60MIN/HOUR) = 48.8 MPH


14/59

An angry driver, after being cut off at the last intersection, pulls up next to

the offender at a stoplight. He gets out of his car with a 5 lb tire iron andproceeds to bash on the roof of the guys car with an acceleration of 50

ft/sec2. What force is imparted to the car with each blow?

PRACTICE

W=mg m = W/g = 5 lb/32.2 ft/sec*2 = .155 slugs

F=ma = .155 slugs x 50 ft/sec*2 = 7.76 lbs


15/59

DEFINITION OF : 1 HORSEPOWER


16/59


17/59


18/59

The engine on your new hot rod is finally broken in.

You take it to a shop to be dyno tested. The dyno

report states that your motor generates 247,000 ft-

lb/sec. If 4 girls = 1 Hp, how many Gp is that?

PRACTICE

Hp = 247,000/550 = 449 Hp

Gp = 4girls/Hp (449 Hp) = 1,796 Gp


19/59


20/59

T = FR T = 70 lb x 5 ft = 350 ft -lb

The dimwit who installed the lug nuts on you girlfriends

car after the last tire rotation used an air impact jackedup to apply 300 ft-lb of Torque on the lug nuts. She has

a flat and calls you screaming that she cant get her tire

off using the 2 ft long tire iron in her trunk. Youre

girlfriends pretty scrawny and can only generate 70 lbs

force. You remember that you left a 5 foot long cheater

bar in her trunk. Can she get her tire off using that?

PRACTICE

which means, you dont

have to quit what you were

doin and go get her.


21/59


22/59


23/59

P = F

A

PASCALS LAW


24/59


25/59


26/59


27/59

In a garage, a car lift is used, compressed air exerts a force

on a small piston with diameter of 5 in. This pressure is

transmitted to a second piston of diameter 15 in. What force

must the compressed air exert in order to lift the a car

weighing 4,000 lb? What Air pressure will produce this force?

PRACTICE

F1 = (A1/A2) x F2 = (2.52)

(7.52)x 4,000 lb = 444 lbs

P1 = F1/A1 = 444 lb/(2.52) = 22.6 psi


28/59

PRACTICE


29/59

HAND OPERATED JACK


30/59

AIR-to-HYDRAULIC BOOSTER

oil

air

air

oil

AA

pP

=

OILOILAIRAIRAPAP =


31/59

AIR TO HYDRAULIC BOOSTER SYSTEM


32/59

POTENTIAL ENERGY DUE TO ELEVATION

POTENTIAL ENERGY UNLEASHED
http://www.youtube.com/watch?v=FdCJzO3w7_M&NR=1http://www.youtube.com/watch?v=FdCJzO3w7_M&NR=1


33/59

POTENTIAL ENERGY DUE TO PRESSURE

Pressure used badly
http://www.youtube.com/watch?v=LAiNW1jlmlUhttp://www.youtube.com/watch?v=LAiNW1jlmlU


34/59

KINETIC ENERGY


35/59

Wile E Coyote teaches physics
http://www.youtube.com/watch?v=Jnj8mc04r9Ehttp://www.youtube.com/watch?v=Jnj8mc04r9E


36/59


37/59


38/59

CONTINUITY

Moving volume
http://www.youtube.com/watch?v=k8IRxT1sM6shttp://www.youtube.com/watch?v=k8IRxT1sM6s


39/59

PRACTICE

EXERCISE


40/59

Load

pump

0 psig


41/59

water zooka
http://www.youtube.com/watch?v=kIgdj0okT3s&feature=relatedhttp://www.youtube.com/watch?v=kIgdj0okT3s&feature=related


42/59


43/59


44/59

WHY DO AIRPLANES FLY?


45/59

BERNOULLI'S PRINCIPLE

TANKER IMPLOSION

UNEDITED TANKER IMPLOSION
http://home.earthlink.net/~mmc1919/venturi.htmlhttp://www.youtube.com/watch?v=Zz95_VvTxZM&feature=relatedhttp://www.youtube.com/watch?v=hsdC9GX1By0&feature=relatedhttp://www.youtube.com/watch?v=hsdC9GX1By0&feature=relatedhttp://www.youtube.com/watch?v=Zz95_VvTxZM&feature=relatedhttp://home.earthlink.net/~mmc1919/venturi.html


46/59

P = H

substituting for P

we can derive this


47/59

write down the basic Bernoulli equation


48/59


49/59


50/59


51/59


52/59


53/59

TORRICELLIS THEOREM


54/59


55/59


56/59

v2=


57/59

ENERGY, POWER AND FLOW RATE IN THE SI SYSTEM

In the English system:

Energy (work) = F x S = lb x ft = lb-ft

Power = Work/t = (lb-ft)/s

from there, we created a derived unit called Horsepower

1HP = 33,000 (ft -lbs )/min1HP = 550 (ft-lbs)/s

In the SI Metric system:

Energy (work) = F x S = 1N x 1m = 1Joule

Power = Work/t = 1J/s = 1 Watt

In the SI system ALL forms of power are expressed in Watts!

1 Hp = 746 Watts


58/59

PUMP HEAD

English

SI


59/59

FLOW RATE

1 (m3/s) = 15,800 gpm, which is very large

Metric Flow Rates are usually specified in:

Liters per second (Lps)

Liters per minute (Lpm)

1 liter = .001 m3

Documents

CH 3 Energy and Power in Hyd Systems (Image Compression)