ABSTRACT CONCEPTUAL INTERNAL DESIGN AND COMPUTATIONAL FLUID DYNAMICS ANALYSIS OF A SUPERSONIC INLET ALEMDAROgLU, Mine M. S., Department of Aerospace Engineering Supervisor: Prof. Dr. Yusuf &Ouml / ZY&Ouml / R&Uuml / K May 2005, 144 pages In this thesis, the conceptual internal design of the air inlet of a supersonic, high altitude, solid propellant ramjet cruise missile is performed. Inviscid, compressible CFD analysis of the designed inlet is made in order to obtain qualitative and quantitative performance characteristics of the inlet at different operating conditions. The conceptual design of the inlet is realized by using analytical relations and equations, correlations derived from numerous available past experimental data and state-of-the-art design examples. The performance estimation of the designed inlet at different operating conditions is done by using one and two dimensional gas dynamics equations. The results of the performance estimation study are compared with the results of the CFD analysis and these results are discussed in detail. A commercial tool, CFD-FASTRAN&Ograve / , is used for the CFD analysis. Inlet flow phenomena such as, different shock patterns and shock positions, performance degradation at off-design operating conditions and inlet unstart are observed. Keywords: Supersonic Inlet, Ramjet, CFD, Inlet Performance Characteristics, Operating Conditions, Unstart

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An aerodynamic and acoustic investigation was performed on two small-scale supersonic inlets to determine which inlet would be more suitable for a High Speed Civil Transport (HSCT) aircraft during approach and takeoff flight conditions. The comparison was made between an axisymmetric supersonic P inlet and a bifurcated two-dimensional supersonic inlet. The 1/14 scale model supersonic inlets were used in conjunction with a 4.1 in (10.4 cm) turbofan engine simulator to provide the typical characteristics of a turbofan aircraft engine. A bellmouth was utilized on each inlet to eliminate lip separation commonly associated with airplane engine inlets that are tested under static conditions. Steady state measurements of the aerodynamic flowfield and acoustic farfield were made in order to evaluate the aeroacoustic performance of the inlets. The aerodynamic results show the total pressure recovery of the two inlets to be nearly identical, 99% at the approach condition and 98% at the takeoff condition. At the approach fan speed (60% design speed), there was no appreciable difference in the acoustic performance of either inlet over the entire 0° to 110° farfield measurement sector. The inlet flow field results at the takeoff fan speed (88% design speed), show the average inlet throat Mach number for the P inlet (Mach 0.52) to be approximately 2 times that of the 2D inlet (Mach 0.26). The difference in the throat Mach number is a result of the smaller throughflow area of the P inlet. This reduced area resulted in a “soft choking” of the P inlet which lowered the blade passing tone of the simulator by an average of 9 dB in the forward sector, when compared to the 2D inlet. / Master of Science

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