Search This Blog

Wednesday, April 18, 2012

PRINCIPLES OF FLOW & PRESSURE IN HYDRAULICS

In the previous post i had explained you about the difference between hydrodynamics and hydrostatics.Hydrostatics is nothing but hydraulics in common language.Pressure and flow are two big terms in hydraulics.In this post i will explain pressure & flow in details.


Pressure explained :


Basically pressure is created in a hydraulic system when there is a resistance to the flow in the system.If there is a load or force which is opposing the free flow of fluid in the system(friction if neglected) then only pressure is created i.e equal to the force divided by the area perpendicular to the opposing force.


pressure = force / perpendicular area in contact with force.


if there is no opposition to the flow then pressure is equal to zero.

pressure head comes from the weight of the fluid.
e.g. A column of air of one square inch as high as atmosphere gives a pressure of one atmosphere at see level i.e 76 mm of mercury or 14.7 psi. 


a pressure gauge is used to measure the pressure but it shows the gauge pressure which is the difference between absolute pressure minus the atmospheric pressure.


gauge pressure =absolute pressure - atmospheric pressure 


psig  = psia - 14.7

* Liquid always seeks a level depending on pressure.
*according to Bernoulli's theorem the sum of pressure energy kinetic energy and the potential energy is constant for a system.
*If the fluid levels are same then the potential energy will be cancelled out hence we have kinetic energy inversely proportional to the pressure energy.


principles of flow :-

Flow is an action in the hydraulic system that gives the actuator its motion.Pressure gives the actuator it's force but flow is essential for the movement.The flow is created by pump.

There are two ways to measure flow rate one is velocity of flow ( feet per second ) and flow rate (liter per minute ).

velocity is the average speed of fluid particles past a particular point in unit time.Flow rate can be defined as the volume of fluid passing a particular point in unit time.

large volumes are measured in GPM (gallons per minute) or LPM (liters per minute) and small flow rates are measured in CC per min.

1 gpm = 231 inch^3 per minute
1 lpm = 1000 cc^3 per minute.

whenever a liquid is flowing then there must be an unbalanced force to cause motion.When a fluid flows in a streamlined path in a straight path then also there is a pressure difference between the start point and downstream.That pressure drop is due to friction and friction causes the pressure drop causing the flow of fluid in the pipe.


 




4 comments:

  1. Traveling is not just about seeing places, but experiencing them deeply. Delhi offers a mix of tradition and modern culture through its food and streets.

    With , you can explore hidden gems while improving your photography skills. These tours guide you through local markets, street food stalls, and cultural spots.

    It’s not just about clicking photos—it’s about understanding the story behind every dish. Perfect for beginners and professionals alike, this experience adds value to your travel memories.

    ReplyDelete
  2. Delhi’s culinary heritage reflects centuries of cultural influence, from Mughal kitchens to modern fusion cuisine. Exploring this rich history requires more than just random food hopping. In the heart of this exploration, food tours with chef in Delhi provide a guided and immersive experience. These tours are led by professionals who understand both food and culture deeply. They take you beyond popular spots and introduce you to hidden culinary treasures. Along the way, you learn about spices, preparation methods, and regional variations. This makes your journey through Delhi’s food scene more meaningful and memorable.

    ReplyDelete
  3. Delhi is known for its rich and diverse food culture. From street food to traditional meals, the city offers endless options for food lovers. Exploring these flavors is an adventure in itself.

    A Food Walk in Delhi is one of the best ways to experience this diversity. It allows you to taste multiple dishes while learning about their origins and significance.

    ReplyDelete