Recent applications of theoretical analysis to V/STOL inlet design

The theoretical analysis methods, potential flow, and boundary layer, used at Lewis are described. Recent application to Navy V/STOL aircraft, both fixed and tilt nacelle configurations, are presented. A three dimensional inlet analysis computer program is described and preliminary results presented. An approach to optimum design of inlets for high angle of attack operations is dicussed

Potential and viscous flow in VTOL, STOL or CTOL propulsion system inlets

A method was developed for analyzing the flow in subsonic axisymmetric inlets at arbitrary conditions of freestream velocity, incidence angle, and inlet mass flow. An improved version of the method is discussed and comparisons of results obtained with the original and improved methods are given. Comparisons with experiments are also presented for several inlet configurations and for various conditions of the boundary layer from insignificant to separated. Applications of the method are discussed, with several examples given for specific cases involving inlets for VTOL lift fans and for STOL engine nacelles

Computer programs for calculating potential flow in propulsion system inlets

Calculational procedure evolved in process of designing inlets. Douglas axisymmetric potential flow program called EOD calculates incompressible potential flow about arbitrary bodies. Program SCIRCL generates input for EOD from inlet components. Program COMBYN takes basic solutions output by EOD and combines them into solutions of interest and applied compressibility correction

Use of experimental separation limits in the theoretical design of V/STOL inlets

Experimental data from several model inlets are used to generate two parameters which are related to the limit of operation for inlet flow separation. One parameter, called the diffusion ratio, is the ratio of the peak velocity on the inlet surface to the velocity at the diffuser exit and is related to the boundary-layer separation at low throat Mach numbers. The other parameter, the peak Mach number on the inlet surface, is related to the separation at high throat Mach numbers. These parameters are easily calculated from potential flow solutions and thus can be used as a design tool in screening proposed inlet geometries. An illustrative example of an application to an inlet design study for a tilt nacelle VTOL airplane is presented. The value of contraction ratio required to meet the operating requirements yet allow the inlet to remain free of separation as indicated by the two separation parameters is shown

Theoretical study of VTOL tilt-nacelle axisymmetric inlet geometries

A systematic theoretical study of VTOL tilt-nacelle inlet design parameters is reported. The parameters considered are internal-lip contraction ratio, internal-lip major-to-minor axis ratio, diffuser-exit-area to throat-area ratio, maximum diffuser wall angle and shape. Each of the inlets was analyzed at the same given flow condition of free-stream velocity, angle between the free stream and centerline of the inlet, and diffuser-exit Mach number. The effects of these geometric parameters on surface static-pressure distribution, peak surface Mach number, diffusion velocity ratio, and tendency for the inlet flow to separate are presented

A framework for molecular biology databases integration using context graph keying.

This paper proposed a novel framework for integrating public domain molecular biology databases with the aid of a context graph. A context graph is used to map data in order to establish an integration domain for the participating multi-resource database federation. Data are presented in a consolidated form upon retrieval from the multiple databases. The approach presented in this paper is novel in the sense that, it can be implemented within a component database and can initiate data consolidation collected from multiple sources without users' intervention. The approach has received considerable interest from the research community

Integration of biological data resources using image object keying.

This paper proposes a novel concept of ‘image object keying'. The work builds on earlier research in this area and shows how the 3D structure of a protein can be retrieved interactively from a gel electrophoresis protein spot. It uses intelligent image matching operations like the Hough Transform and Edge Detection techniques. Unique aspects are that searches may be initiated from multiple biological resources but with the results being integrated into a single page. A significant outcome of this work is that it enables researchers to search the database without the need to write and complex script

An approach to optimum subsonic inlet design

Inlet operating requirements are compared with estimated inlet separation characteristics to identify the most critical inlet operating condition. This critical condition is taken to be the design point and is defined by the values of inlet mass flow, free-stream velocity and inlet angle of attack. Optimum flow distributions on the inlet surface were determined to be a high, flat top Mach number distribution on the inlet lip to turn the flow quickly into the inlet and a flat bottom skin-friction distribution on the diffuser wall to diffuse the flow rapidly and efficiently to the velocity required at the fan face. These optimum distributions are then modified to achieve other desirable flow characteristics. Example applications are given

Optimum subsonic, high-angle-of-attack nacelles

The optimum design of nacelles that operate over a wide range of aerodynamic conditions and their inlets is described. For low speed operation the optimum internal surface velocity distributions and skin friction distributions are described for three categories of inlets: those with BLC, and those with blow in door slots and retractable slats. At cruise speed the effect of factors that reduce the nacelle external surface area and the local skin friction is illustrated. These factors are cruise Mach number, inlet throat size, fan-face Mach number, and nacelle contour. The interrelation of these cruise speed factors with the design requirements for good low speed performance is discussed

Theoretical flow characteristics of inlets for tilting-nacelle VTOL aircraft

The results of a theoretical investigation of geometric variables for lift-cruise-fan, tilting nacelle inlets operating at high incidence angles are presented. These geometric variables are investigated for their effects on surface static to free stream pressure ratio, and the separation parameters of maximum to diffuser exit surface velocity ratio and maximum surface Mach number for low speed operating conditions. The geometric parameters varied were the internal lip contraction ratio, external forebody to diffuser exit diameter ratio external forebody length to diameter ratio and internal lip major to minor axis ratio