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Wing Embedded Engines For Large Blended Wing Body Aircraft. A Computational Investigation Michael Farrow MEng Aerospace Engineering. Introduction. Why? Embedded Engines Blended Wing Bodies Method CAD Meshing Solving Results Obtained Problems Encountered Conclusions Questions.
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Wing Embedded EnginesForLarge Blended Wing Body Aircraft A Computational Investigation Michael Farrow MEng Aerospace Engineering
Introduction • Why? • Embedded Engines • Blended Wing Bodies • Method • CAD • Meshing • Solving • Results Obtained • Problems Encountered • Conclusions • Questions
The First Jet Airliner • The de Havilland DH-106 Comet 1 • First Flew in 1949 • Four Fully Embedded dH Ghost 50 Turbojets [1]
[2] [3] [4] [5] [7] [6] Embedded Engines
For Reduction in Weight Reduction in Viscous Drag Potential Reduction in Pressure Drag Potential Noise Reduction Against Optimisation of Inlet Efficiency is Difficult Engine Failures/Fires are More Dangerous Maintenance and Upgrade Hampered by Structure The Embedded Argument
[10] [9] The Blended Wing Body • Smoothly Sweeps Wings into Fuselage • Complete Lifting Body • Large Cargo Volume to Wingspan Ratio
Construction of CAD Geometry • Sampled from Public Domain Images • 3 Test Cases
Drag Estimation • Required for Engine Sizing • Skin Friction Drag • Estimated Using Thin Plate Aerodynamics • Pressure Drag • Function of the Projected Cross Sectional Area • Induced Drag from the Lift Coefficient & Span Efficiency
Construction of Mesh • Unstructured Tetrahedral Mesh using ICEM CFD • Prism Layer Grown Outwards from Surfaces
Results - Clean Contours of Static Pressure (Pascals)
Results - Clean Contours of Static Pressure (Pascals)
Results – Podded Contours of Static Pressure (Pascals)
Results - Embedded Contours of Static Pressure (Pascals)
Problems Encountered • Insufficient Mesh Quality • Underexpanded Jet Exhaust – Unphysical Results
Conclusions • Embedded Configuration Optimal - External Aerodynamics • Minimum Lift Loss • Less Viscous Drag than Podded • Less Pressure Drag than Podded AND Clean • However: • Optimisation Required for Both Configurations • Serious Structural Questions Remain • Design & Investigation of Duct Flow Required
References • http://bose.utmb.edu/tdpower/Comet.jpg • http://www.palba.cz/forumfoto/albums/USA_Letectvo/normal_Yb-49_01.jpg • http://img.dailymail.co.uk/i/pix/2007/05_02/Vulcan260507_468x308.jpg • http://library.thinkquest.org/04oct/02032/poze/b2spirit_4.jpg • http://www.abpic.co.uk/images/images/1080254M.jpg • http://www.flightglobal.com/airspace/photos/apgphoto/images/619/raf-nimrod-mra4.jpg • http://plane-crazy.purplecloud.net/Aircraft/Jets/Valiant/Valiant-B1.jpg • http://media.nowpublic.net/images//44/5/44546fb20c750216d0a98359a2280ab8.jpg • http://www.flightglobal.com/blogs/aircraft-pictures/BWBlarge.jpg • NASA Facts – July 1997 – The Blended Wing Body
Solution • Spalart-Allmarus Scheme • Initial Incompressible Solution feeds Compressible • Boundary Conditions - Cruise Conditions for BWB Aircraft • Pressure Far Field • 12,000m ISA • Mach 0.85 • Engine Inlet & Exhaust Conditions from Engine Model
Engine Modelling • GE90-115B Turbofan • Thermodynamic Mapping by Stage • Perfect Scaling Assumed
Jet Flow Contours of Mach Number