Gentelmen, All those,who are graduated in chemical engineering are kindly asked to open their old tekstbooks on "Heat,Momentum and Mass Transfer" ( 3rd,4th and 5th semester in faculties of chemical engineering).Basic books used to be McCabe-Smith and W.W.W. ( Whelty + 2 other with W ) .At least those were my books more than 30 years ago. Edward Szpruch Eltek Ltd P.O.Box 159 ; 49101 Petah Tikva Israel Tel ++972 3 9395050 , Fax ++972 3 9309581 e-mail [log in to unmask] > -----Original Message----- > From: Rummy Makmur [SMTP:[log in to unmask]] > Sent: ג נובמבר 13 2001 14:12 > To: [log in to unmask] > Subject: Re: [TN] Formula? > > To prove that, you need combination of mass balance and mechanical energy > balance (i.e. bernoulli equation). > > mass balance: mass rate in = mass rate out. Assuming incompressible fluid > (same density in and out), since mass rate = volume rate * density, > density > get canceled out and the result is volume rate in = volume rate out. It is > also known that volume rate = velocity * Area. From this you can prove > that, > if area is decreased (such as, putting your thumb on the hose), velocity > will increase. > > Then you will need bernouli equation. Simplified Bernoulli Equation: > (P1/density) + (Velocity1^2/2)+ (gh1) = (P2/density) + (velocity2 ^ 2/ 2) > + > (gh2) > > Assuming h (height) is the same, they get canceled out. Then, you will > have > an equation with only P (Pressure) and V (velocity) as variables which you > can use to prove that if V2 increases, P2 decreases, provided P1 and V1 > are > constant. > > So, volume rate at location 2 is not dependent on Pressure at location 2, > provided same pressure and volume rate coming in. It "feels" like pressure > increasing, but rather it's velocity that is increasing or kinetic energy > increases. > > Check out these sites > http://physics.bu.edu/py105/notes/Bernoulli.html > http://rabi.phys.virginia.edu/HTW/water_distribution.html > > For the second question, you might not be able to use same exact equations > for air, since air might be considered as compressible. It may involve > more > complicated equations. > > Rummy Makmur > Process Engineer > Ibiden Circuits of America > > -----Original Message----- > From: Eric Christison [mailto:[log in to unmask]] > Sent: Tuesday, November 13, 2001 3:27 AM > To: [log in to unmask] > Subject: Re: [TN] Formula? > > > I think you're all barking up the wrong tree. > > Bernoulli's equations shows the conservation of kinetic energy in fluids > and is generally used to calculate things like areodynamic lift on an > aerofoil or the forces exerted on a pipe wall as the the contents flows > round a corner. > > I think you're searching for P1v1/T1 = P2v2/T2. However v is not volume > but specific volume ie m^3/Kg. > > Spend a minute on a reality check. If you put your thumb on the end of a > hose pipe does the pipe get smaller? If not, how can the volume of the > pipe decrease? > > Hope this helps, > > > > [log in to unmask] wrote: > > > > Ray, try http://www.lmnoeng.com/Flow/bernoulli.htm > > > > -----Original Message----- > > From: TechNet [mailto:[log in to unmask]]On Behalf Of Golembiewski, Ray > > Sent: Monday, November 12, 2001 14:34 > > To: [log in to unmask] > > Subject: [TN] Formula? > > > > What is the formula that proves when I put my thumb on the end > > of a garden house, the pressure increases and volume decreases. Is the > > same formula used with air? Please help, > > > > Ray Golembiewski C.I.D. > > Manufacturing Test Engineer > > Projects Unlimited, Inc. > > (937) 918-2200 > > > -- > Eric Christison > Mechanical Engineer > STMicroelectronics > 33 Pinkhill > Edinburgh > EH12 7BF > > Tel: (0)131 336 6165 > Fax: (0)131 336 6001 > > -------------------------------------------------------------------------- > -- > ----- > Technet Mail List provided as a free service by IPC using LISTSERV 1.8d > To unsubscribe, send a message to [log in to unmask] with following text in > the BODY (NOT the subject field): SIGNOFF Technet > To temporarily halt delivery of Technet send the following message: SET > Technet NOMAIL > Search previous postings at: www.ipc.org > On-Line Resources & Databases > > E-mail Archives > Please visit IPC web site (http://www.ipc.org/html/forum.htm) for > additional > information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 > ext.5315 > -------------------------------------------------------------------------- > -- > ----- > > -------------------------------------------------------------------------- > ------- > Technet Mail List provided as a free service by IPC using LISTSERV 1.8d > To unsubscribe, send a message to [log in to unmask] with following text in > the BODY (NOT the subject field): SIGNOFF Technet > To temporarily halt delivery of Technet send the following message: SET > Technet NOMAIL > Search previous postings at: www.ipc.org > On-Line Resources & Databases > > E-mail Archives > Please visit IPC web site (http://www.ipc.org/html/forum.htm) for > additional > information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 > ext.5315 > -------------------------------------------------------------------------- > ------- --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------