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In fluid mechanics the term static pressure has several uses:

  • In the design and operation of aircraft, static pressure is the air pressure in the aircraft’s static pressure system.
  • In fluid dynamics, static pressure is the pressure at a nominated point in a fluid. Many authors use the term static pressure in place of pressure to avoid ambiguity.
  • The term static pressure is also used by some authors in fluid statics.

Static pressure in design and operation of aircraft

An aircraft’s altimeter is operated by the static pressure system. An aircraft’s airspeed indicator is operated by the static pressure system and the pitot pressure system .[1]

The static pressure system is open to the exterior of the aircraft to sense the pressure of the atmosphere at the altitude at which the aircraft is flying. This small opening is called the static port. In flight the air pressure is slightly different at different positions around the exterior of the aircraft. The aircraft designer must select the position of the static port carefully. There is no position on the exterior of an aircraft at which the air pressure, for all angles of attack, is identical to the atmospheric pressure at the altitude at which the aircraft is flying.[2] The difference in pressure causes a small error in the altitude indicated on the altimeter, and the airspeed indicated on the airspeed indicator. This error in indicated altitude and airspeed is called position error.[3] [4]

When selecting the position for the static port, the aircraft designer’s objective is to ensure the pressure in the aircraft’s static pressure system is as close as possible to the atmospheric pressure at the altitude at which the aircraft is flying, across the operating range of weight and airspeed. Many authors describe the atmospheric pressure at the altitude at which the aircraft is flying as the freestream static pressure. At least one author takes a different approach in order to avoid a need for the expression freestream static pressure. Gracey has written "The static pressure is the atmospheric pressure at the flight level of the aircraft". [5][6] Gracey then refers to the air pressure at any point close to the aircraft as the local static pressure.

Static pressure in fluid dynamics

The concept of pressure is central to the study of fluids. A pressure can be identified for every point in a body of fluid, regardless of whether the fluid is in motion or not. Pressure can be measured using an aneroid, Bourdon tube, mercury column, or various other methods.

The concepts of total pressure and dynamic pressure arise from Bernoulli's equation and are significant in the study of all fluid flows. (These two pressures are not pressures in the usual sense - they cannot be measured using an aneroid, Bourdon tube or mercury column.) To avoid potential ambiguity when referring to pressure in fluid dynamics, many authors use the term static pressure to distinguish it from total pressure and dynamic pressure. Static pressure is identical to pressure and can be identified for every point in a fluid flow field.

In Aerodynamics, L.J. Clancy[7] writes: "To distinguish it from the total and dynamic pressures, the actual pressure of the fluid, which is associated not with its motion but with its state, is often referred to as the static pressure, but where the term pressure alone is used it refers to this static pressure."

Bernoulli's equation is fundamental to the dynamics of incompressible fluids. In many fluid flow situations of interest, changes in elevation are insignificant and can be ignored. With this simplification, Bernoulli’s equation for incompressible flows can be expressed as[8][9][10]

where:

Every point in a steadily flowing fluid, regardless of the fluid speed at that point, has its own static pressure , dynamic pressure , and total pressure . Static pressure and dynamic pressure are likely to vary significantly throughout the fluid but total pressure is constant along each streamline. In irrotational flow, total pressure is the same on all streamlines and is therefore constant throughout the flow.[11]

The simplified form of Bernoulli's equation can be summarised in the following memorable word equation: [12] [13] [14]

static pressure + dynamic pressure = total pressure.

This simplified form of Bernoulli’s equation is fundamental to an understanding of the design and operation of ships, low speed aircraft, and airspeed indicators for low speed aircraft – that is aircraft whose maximum speed will be less than about 30% of the speed of sound.

As a consequence of the widespread understanding of the term static pressure in relation to Bernoulli’s equation, many authors [15] in the field of fluid dynamics also use static pressure rather than pressure in applications not directly related to Bernoulli’s equation.

The British Standards Institution, in its Standard[16] Glossary of Aeronautical Terms, gives the following definition:

4412 Static pressure The pressure at a point on a body moving with the fluid.

Static pressure in fluid statics

The term static pressure is sometimes used in fluid statics to refer to the pressure of a fluid at a nominated depth in the fluid. In fluid statics the fluid is stationary everywhere and the concepts of dynamic pressure and total pressure are not applicable. Consequently there is little risk of ambiguity in using the term pressure, but some authors[17] choose to use static pressure in some situations.

See also

Notes

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References

Aircraft design and operation

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  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

    In case you are in search of an actual estate or Singapore property agent on-line, you simply should belief your intuition. It's because you do not know which agent is nice and which agent will not be. Carry out research on several brokers by looking out the internet. As soon as if you end up positive that a selected agent is dependable and reliable, you can choose to utilize his partnerise in finding you a home in Singapore. Most of the time, a property agent is taken into account to be good if he or she locations the contact data on his website. This may mean that the agent does not mind you calling them and asking them any questions relating to new properties in singapore in Singapore. After chatting with them you too can see them in their office after taking an appointment.

    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

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  • Many property agents need to declare for the PIC grant in Singapore. However, not all of them know find out how to do the correct process for getting this PIC scheme from the IRAS. There are a number of steps that you need to do before your software can be approved.

    Naturally, you will have to pay a safety deposit and that is usually one month rent for annually of the settlement. That is the place your good religion deposit will likely be taken into account and will kind part or all of your security deposit. Anticipate to have a proportionate amount deducted out of your deposit if something is discovered to be damaged if you move out. It's best to you'll want to test the inventory drawn up by the owner, which can detail all objects in the property and their condition. If you happen to fail to notice any harm not already mentioned within the inventory before transferring in, you danger having to pay for it yourself.

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    Have handed an trade examination i.e Widespread Examination for House Brokers (CEHA) or Actual Property Agency (REA) examination, or equal; Exclusive brokers are extra keen to share listing information thus making certain the widest doable coverage inside the real estate community via Multiple Listings and Networking. Accepting a severe provide is simpler since your agent is totally conscious of all advertising activity related with your property. This reduces your having to check with a number of agents for some other offers. Price control is easily achieved. Paint work in good restore-discuss with your Property Marketing consultant if main works are still to be done. Softening in residential property prices proceed, led by 2.8 per cent decline within the index for Remainder of Central Region

    Once you place down the one per cent choice price to carry down a non-public property, it's important to accept its situation as it is whenever you move in – faulty air-con, choked rest room and all. Get round this by asking your agent to incorporate a ultimate inspection clause within the possibility-to-buy letter. HDB flat patrons routinely take pleasure in this security net. "There's a ultimate inspection of the property two days before the completion of all HDB transactions. If the air-con is defective, you can request the seller to repair it," says Kelvin.

    15.6.1 As the agent is an intermediary, generally, as soon as the principal and third party are introduced right into a contractual relationship, the agent drops out of the image, subject to any problems with remuneration or indemnification that he could have against the principal, and extra exceptionally, against the third occasion. Generally, agents are entitled to be indemnified for all liabilities reasonably incurred within the execution of the brokers´ authority.

    To achieve the very best outcomes, you must be always updated on market situations, including past transaction information and reliable projections. You could review and examine comparable homes that are currently available in the market, especially these which have been sold or not bought up to now six months. You'll be able to see a pattern of such report by clicking here It's essential to defend yourself in opposition to unscrupulous patrons. They are often very skilled in using highly unethical and manipulative techniques to try and lure you into a lure. That you must also protect your self, your loved ones, and personal belongings as you'll be serving many strangers in your home. Sign a listing itemizing of all of the objects provided by the proprietor, together with their situation. HSR Prime Recruiter 2010
  • Kermode, A.C. (1972) Mechanics of Flight, Longman Group Limited, London ISBN 0-582-23740-8
  • Lombardo, D.A., Aircraft Systems, 2nd edition, McGraw-Hill (1999), New York ISBN 0-07-038605-6

Fluid dynamics

  • Clancy, L.J. (1975), Aerodynamics, Pitman Publishing Limited, London ISBN 0-273-01120-0
  • Streeter, V.L. (1966), Fluid Mechanics, McGraw-Hill, New York
  1. Lombardo, D.A., Aircraft Systems, 2nd edition – chapter 2
  2. "It is virtually impossible to find a position where the static pressure is always exactly the same as the pressure in the free airstream away from the aircraft". Kermode, A.C., Mechanics of Flight, 10th edition – page 65
  3. Kermode, A.C., Mechanics of Flight, 10th Edition – page 65
  4. "Of these errors the error in detection of static pressure is generally the most serious and has the special name, position error." Dommasch, D.O., Sherby, S.S., and Connolly, T.F. (1967) Airplane Aerodynamics, 4th edition – page 51, Pitman Publishing Corp., New York
  5. Gracey, William, Measurement of aircraft speed and altitude NASA, RP-1046, page 1
  6. Gracey, William, Measurement of Aircraft Speed and Altitude, page 1
  7. Clancy, L.J., Aerodynamics, page 21
  8. Clancy, L.J., Aerodynamics, equation 3.13
  9. Hurt, H.H. Jr, (1960), Aerodynamics for Naval Aviators, page 9, A National Flightshop Reprint, Florida
  10. Anderson, J.D. Jr, Fundamentals of Aerodynamics, 4th edition – page 212, McGraw-Hill, New York. ISBN 978-0-07-295046-5
  11. A.M. Kuethe and J.D. Schetzer (1959), Foundations of Aerodynamics, Section 3.5 (2nd edition), John Wiley & Sons, Inc. New York ISBN 0-471-50952-3
  12. Clancy, L.J., Aerodynamics, Section 3.5
  13. ”The total pressure is composed of two parts, the static pressure and the dynamic pressure”. Streeter, V.L., Fluid Mechanics 4th edition – page 404
  14. NASA's guide to Bernoulli's Equation
  15. For example: Abbott, I.H. and Von Doenhoff, A.E. (1949) Theory of Wing Sections, Navier-Stokes equations - section 5.4. Dover Publications, Inc., New York. Standard Book Number 486-60586-8
  16. British Standard BS 185: Part 1: 1950 Glossary of Aeronautical Terms
  17. For example: "The pressure in cases where no motion is occurring is referred to as static pressure." Curtis D. Johnson, Process Control Instrumentation Technology, Prentice Hall (1997)