Examples & Uses of JetsJSF - STOVL VersionLockheed-Martin X-35 (CDP)USMC Version*Boeing X-32 (CDP)USMC Version** Images obtained from the Official US Government, DOD, JSF SiteJet Entrainment FlowHot Gas Ingestion into inletFountain Upwash FlowGround Erosion RegionGround PlaneJet Impingement RegionLifting-Jet FlowWall-Jet FlowUnsteady StructuralLoads and Lift LossJet Entrainment FlowHot Gas Ingestion into inletFountain Upwash FlowGround Erosion RegionGround PlaneJet Impingement RegionLifting-Jet FlowWall-Jet FlowUnsteady StructuralLoads and Lift LossJet Entrainment FlowHot Gas Ingestion into inletFountain Upwash FlowGround Erosion RegionGround PlaneJet Impingement RegionLifting-Jet FlowWall-Jet FlowUnsteady StructuralLoads and Lift LossWall-Jet FlowUnsteady StructuralLoads and Lift LossGround Effect for a STOVL aircraft in hoverExamples & Uses of JetsExamples & Uses of JetsF22 RaptorF-18Supersonic Inlets & Diffusers(http://www.grc.nasa.gov/WWW/K-12/airplane/lowsup.html)Micro-nozzles400 μm200 μm50 μmHumanHair 100 μmInlet pressure holePressure tap holeSettling chamber(Supersonic) MicrojetsConverging/Sonic Micro- nozzlesC-D Micro-nozzles400 μm ; PO~ 120 Psi 200 μm ; PO~ 120 Psi 100 μm ; PO~ 100 Psi Flow Visualization ResultsSupersonic MicrojetsSupersonic JetsMach 2 Rectangular JetsSonic Roundμjet (0.4 mm)Vectored RectangularJetsMach 2 Round vectored Jet (~30 mm)Jet PropertiesSummary of (some) Fluids Concepts Learned in 3015C (cont’d)Conservation of Momentum - If viscosity is neglected:Euler’s Equation¾ Integrate Euler’s equation along a streamline to obtain Bernoulli’s EquationIt is only valid for : incompressible fluids, steady flow along a streamline, no energy loss due to friction, no heat transfer¾ Conservation of Energy - If energy is added, removed or lost via pumps turbines, friction, etc.then we use the energy equation or Extended Bernoulli’s Equation:0=++ gdzVdVdpρρConstant 2222221211=++=++ gzVpgzVpρρFlow work + kinetic energy + potential energy = constant2222121122 zgVphhhzgVpLEA++=−−+++γγWhere hA, hEis work done by or on the systems, e.g turbines, pumps, etc. and hLisFrictional Head Loss where⎟⎟⎠⎞⎜⎜⎝⎛⎟⎠⎞⎜⎝⎛=⇒⎟⎠⎞⎜⎝⎛⎟⎟⎠⎞⎜⎜⎝⎛=gVDLfDLghwL2 42ρτPitot probesConstant 2222221211=++=++ gzVpgzVpρρ¾ At station 1, the fluid is moving:¾ P1= PstaticOR simply Ps V1= V¾At station 2, the fluid is rest:¾ P2= PpitotOR PtotalOR PstognationOR P0 and V2= 0 (fluid is at rest)¾Hence, Bernoulli’s Equation is reduced to:1 2Constant