Engineering Fluid Mechanics
Engineering Fluid Mechanics ENGR 335
Popular in Course
Popular in General Engineering
Mr. Walton Littel
verified elite notetaker
This 5 page Class Notes was uploaded by Mr. Walton Littel on Friday October 23, 2015. The Class Notes belongs to ENGR 335 at University of Idaho taught by Staff in Fall. Since its upload, it has received 13 views. For similar materials see /class/227749/engr-335-university-of-idaho in General Engineering at University of Idaho.
Reviews for Engineering Fluid Mechanics
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 10/23/15
39 6 I EA A marcuxykcroscne mannamar is connected to the Pilot 39 tube as shown Ifthc de ection on he manomctcr is 7 in what is Eh kerosene velocity in th pipe Alumna that the spaci c gravity o the keroscn is 081 11 rdquot EXAMPLE g2 22 44 V Fmo ngoserlg VELoch i sowrmm39 PITOT usTATIC Tues EQUMWN FEW PAGE Me 2 T5177 V V23 P 3 Z39 22m1 m NOMETER 3 USED To quotMEASURE LP P us PlEZomerel HEAD cQuATou To HIV 6 To P XKOPq 3124 39Z4CQ E To 54Xm24 7193 3492 pp gt3 b m2339z4 3m7 7 0 P2XK213P3 KZ3721 C2339C Q7 comBmE 74555 EQUATwus To LIMNATE F3 409 4 G ro b 4P 3 KZ39 ro 431433 34 a ppm a my 3124 T0 E I92 3342123 PF 37w 31424 D s 2123 I Iti PJ 391 b7 439 YK C Q C C 314 Km XK7 XKC V 7Z 72Cj BUT 2 39zz 7IN V VJ v25 NAMEDquotE 76 WH Plausible falsehood is still being taught Aerodynamics teaching at grade through high school level as well as teaching at college level is seriously flawed The most popular lower level theory of wing operation which we may call Hump Theory because it requires a wing to have a more convex upper surface as compared to the lower is easily shown to be false Hump theory is based on the Bernoulli theorem according to which pressure and velocity are inversely related and on a principle of equal transit times according to which air passage over an upper wing surface must occur in the same time as air passage below If both of these premises are valid then in orderto have the same transit time flow at a more curved upper wing surface having a longer path must be of greater velocity than that at a less curved lower surface and upper surface pressure must then be less than that at the lower in accordance with the Bernoulli theorem Unfortunately the premises are not both valid Hump theory does not allow for balsa toy gliders with flat wings which fly quite well and it does not allow for inverted flight of aerobatic airplanes For a mathematical proof that the theory is false consider one the most popular trainers the Cessna 150 or 152 which has wings of 160 square feet total area upper surface path about 16 percent longer than the lower and can fly at 55 miles per hour Calculated according to hump theory lift at that speed would be about 40 pounds a small fraction of the 1600 pounds rated gross weight ofthe airplane Calculated minimum flying speed for the airplane according to hump theory is over 300 miles per hour well above the redlined dive speed of 160 miles per hour The problem with hump theory is in the assumption of equal transit times which has no basis in known physics and is quite wrong In fact upper surface transit time in normal flight is always less than that below Despite being quite wrong this theory of flight is still being included in books from otherwise reputable publishers such as National Geographic Macmillan and others in this country and abroad Aerodynamic lift of a wing can be explained and calculated through simple application of Newtonian physics In a perspective of a stationary lifting wing in passing air flow the flow through quotflow attachmentquot otherwise known as quotCoanda effectquot follows the contours of the wing so as to depart in a somewhat downward direction pointed by the converging aft surfaces In a different but equivalent perspective an airfoil moving horizontally through still air leaves air at the trailing edge moving nearly vertically downward behind the converging upper and lower surfaces In either perspective direction of air into downward movement continuously produces downward air mass momentum which is left behind Upward reaction force or lift is equal to the downward rate of change of air momentum in accordance with Newtonian principles Pressure reduction at the upper surface is due to an upward centrifugal pressure gradient in the downwardly curving flow This gradient opposes atmospheric pressure and causes upper surface pressure reduction At the lower surface pressure increase occurs as the lower surface pushes Mair down to also produce an upward pressure gradient increasing lower surface pressure These effects can be demonstrated by blowing air over a sheet of paper which droops from the horizontal Air blown over the upper surface so that flow curves downward produces an upward centrifugal pressure gradient opposing atmospheric pressure causing upper surface pressure reduction and lift lf air is blown beneath the paper then the upward pressure gradient in downward curving flow adds to atmospheric pressure at the lower surface pressure to again produce upward lift Understanding of recirculation is the key to understanding effects of wing sweep washout taper aspect ratio camber and span A more complete story is presented in forums at EAA Oshkosh convention and Lakeland SunNFun The 1999 Oshkosh forum will be on July 30th at 7PM and the SunNFun forum will be April 16th at 1 PM A detailed 160 page book on the subject with over 100 illustrations titled quotStop Abusing Bernoulli How Airplanes Really Flyquot ISBN 09646806 2 9 is available from WVWVAmazoncom VWVWBarnesandNoblecom or from The Academy of Model Aeronautics museum bookstore phone 7652871256 ext 501 Copyright 1998 Gale M Craig T Optical Electrical Control Chemical Reaction Direcl Injection Tufl Wall liace o GAS I LIQUID Mom 39 quot39 quot MZINTERFER0A1 I II 5C 39 EEJ ueugw aee 1 SMQK wmg39 39 SPARK Tancgn39 HYDROGEN BUBBLE ELECTROLYTIC COLORATION39 39 mTER TRACER quot INIE R Ft wo RF 39 quot 5 955mg TIME LINE39 FLOATING39 i SUSPENSION PATH NE39 PA H LINE ELEQIROLYTIC39 gymn THg gAOSEHSIsLE EINT39 W M A H M m SUBLIMATlON g L 1 l 1 1 l 1 Tquot L l 1 39 OIL Fu39M39 OJ 02 QSl 2 5 l 2 5 IO 20 50 f 2 5 O 20 50 IOOZOOI 2 3 5 IO 2039 L f39lquotll39l 1S39 quot quot Lquot quotCn39lS I39DS quotJ Flow Velocity Fig 2 Applicable ow range for each flow visualization method gig Universion Idaho 1 2 1 cl mAKE 0k AS A 5 WALL TAP l PT39J SMALL ggt gt 5 iii fitE v 1 HARD mil 1 G I VENS 5199aan ran4 as 54an 5am F ND NET FORCE zrv V kicraru TfNDNG ro PULL 7mm amber V I 7 FL VE i saw rtev Fs D i R7 REACTION FanE 2 F7 0 Magma 1Q FDRCE ILAN E 2 PRESSdRE Paine INTEbQAYE Y WWV9 DF TD FWD PRESSURE FJKQE V Rcose n awe x PRESSOEE L mFauEm39 M 541 a m V I w Winnp of kwc RV 3 Fr 5M Mimosa Role W cl aumFE ENCE at eme 2 J7 A RY TR t 59 sme use 49 7215 zozrrr7 sme case i 3M 26 l R7 zz z5f5stdb WWWSr Liquot os2ej R7 E51quot JZT RZF Average shear stress coefficient C 001 0009 0oos 0007 0006 I 0005 1 0004 0003 0002 quot 0001 105 Turbulent 7 39 qgamd wt 7 7 Refs Boundary iayer trip V x Cf 133 r Cf Reg2 I g 107 108 Reynolds number UOLv ln2006ReL quot Re 3 t 109 1010
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'