Mach 4 Performance of a Fixed-Geometry Hypersonic Inlet with Rectangular-to-Elliptical Shape Transition
Wind-tunnel testing of a hypersonic inlet with rectangular-to-elliptical shape transition has been conducted at Mach 4.0. These tests were performed to investigate the starting and back-pressure limits of this fixed-geometry inlet at conditions well below the Mach 5.7 design point. Results showed that the inlet required side spillage holes in order to self-start at Mach 4.0. Once started, the inlet generated a compression ratio of 12.6, captured almost 80% of available air and withstood a back-pressure ratio of 30.3 relative to tunnel static pressure. The spillage penalty for self-starting was estimated to be 4% of available air. These experimental results, along with previous experimental results at Mach 6.2 (Smart, M.K, “Experimental Testing of a Hypersonic Inlet with Rectangular-to-Elliptical Shape Transition”, Journal of Propulsion and Power, Vol. 17, No. 2, pp 276-283, 2001)indicate that fixed-geometry inlets with rectangular-toelliptical shape transition are a viable configuration for airframe-integrated scramjets that operate over a significant Mach number range.
Scramjet Inlets Professor
The supersonic combustion ramjet, or scramjet, is the engine cycle most suitable for sustained hypersonic flight in the atmosphere. This article describes some challenges in the design of the inlet or intake of these hypersonic air-breathing engines. Scramjet inlets are a critical component and their design has important effects on the overall performance of the engine. The role of the inlet is first described, followed by a description of inlet types and some past examples. Recommendations on the level of compression needed in scramjets are then made, followed by a design example of a three-dimensional scramjet inlet for use in an access-to-space system that must operate between Mach 6 and 12. NOMENCLATURE A area (m) Cf skin friction coefficient D diameter (m); Drag (N) fst stoichiometric ratio F stream thrust (N) Fadd additive drag (N) Fun uninstalled thrust (N) h enthalpy (289K basis) (J/kg) hpr heat of combustion (J/kg of fuel) Ht total enthalpy (298K basis) (J/kg) L length (m) mc mass capture ratio m& mass flow rate (kg/s) M Mach number P pressure (Pa) Q heat loss (kJ) q dynamic pressure (Pa) T temperature (K); thrust (N) u,V velocity (m/s) x axial distance (m) φ equivalence ratio θ constant in mixing curve ηc combustion efficiency ηKE kinetic energy efficiency ηKE_AD adiabatic kinetic energy efficiency ηo overall scramjet efficiency ηn nozzle efficiency Subscript c cowl comb combustor f fuel in inflow out outflow isol isolator n,N nozzle SEP separation Report Documentation Page Form Approved OMB No. 0704-0188 Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. 1. REPORT DATE SEP 2010 2. REPORT TYPE N/A 3. DATES COVERED 4. TITLE AND SUBTITLE Scramjet Inlets 5a. CONTRACT NUMBER
Laminar heat or mass transfer in rectangular channels and in cylindrical tubes for fully developed flow: comparison of solutions obtained for various boundary conditions
Abstract A comparison is made of results obtained with various boundary conditions at the wall of the channels. By comparing blood Sherwood numbers for finite wall resistance with those for constant concentration boundary condition only a small variation is found for various points along the blood channel.