Design & Construction of subsonic wind Tunnel focusing on two dimensional contraction cone profile using sixth order polynomial (Design of Subsnic Wind Tunnel Contraction cone profile through CFD Simulation) Kashif Javed 1 1 Assistant Professor, Department of Mechanical, Mechatronics & Manufacturing Engineering University of Engineering & Technology, KSK Campus Lahore, Pakistan kashif_javed@uet.edu.pk mech.kashifjaved@gmail.com javed@ualberta.ca Mazhar Ali 2 2 Lecturer, Department of Mechanical Engineering, University of Lahore, Pakistan Student, Skolkovo institute of Science & Technology (MIT collaboration), Moscow, Russia mazhar.ali@skolkovotech.ru mazhar_a@mit.edu Abstract This research work is focused on design and construction of subsonic laboratory wind tunnel with “Ma=0.1”.During wind tunnel design, mostly difficulties arise in generating a profile for contraction cone; that must be selected to achieve uniform flow with negligible losses and boundary layer growth. Since, the design of contraction cone requires proper selection of polynomial equation, A sixth order polynomial was chosen to get a smooth design of contraction cone. The design work was completed through CFD analysis using “ANSYS-FLOTRAN” in which velocity & pressure contour profiles were finalized after analyzing 12 different contraction cone profiles. The current research not only includes verification of contraction cone design by comparing the velocity of air at different sections obtained during CFD analysis with the experimental values at corresponding points; but also covers proper selection of low cost material for test section, diffuser, contraction cone, instrumentation as well as size and type of fan. Keywords: 2D, contraction cone, design optimization, CFD, subsonic, wind tunnel, manometer Nomenclature: Ρ w Density of water (kg/mᶟ) Ρ a Density of air (kg/mᶟ) g Gravitational acceleration (m/sec²) h m Head of water in manometer (m) P Pressure (Pa) Pa Pascal (S.I Unit of Pressure) a,b,c,d,e,f,g, Polynomial coefficients Q Discharge (mᶟ/sec or ftᶟ/min) h Height (m) I Axial distance to point of inflection (m) L Total length of contraction cone (m) x, y Cartesian coordinates (streamwise, vertical) α Curvature at inlet (/m) ‘ d/dx ‘’ d²/dx² 2D Two Dimensional CFM Cubic Feet Per Minute U Axial velocity (m/sec) V Redial velocity (m/sec) Y Redial distance (m) X Axial distance (m) A Area (m²) 1. INTRODUCTION Wind tunnels have proven to be the most advantageous and demanding equipment in science and technology. They have been extensively used to understand the effects of air resistance on automotive and aeronautical objects. This research uses computational as well as experimental techniques in order to validate primarily the contraction cone design for a subsonic (low speed), open circuit, laboratory wind tunnel. The stated equipment was designed and fabricated for the purpose of carrying out research including testing and experimentation in laboratory on different Airfoils associated with small aerodynamic and automotive models. The maximum velocity attained at test section was 35 m/sec. Though the current work Scientific Cooperations International Workshops on Engineering Branches 8-9 August 2014, Koc University, ISTANBUL/TURKEY 287