A preliminary design study of supersonic through-flow fan inlets

From Mach 3.20 cruise propulsion systems, preliminary design studies for two supersonic through-flow fan primary inlets and a single core inlet were undertaken. Method of characteristics and one dimensional performance techniques were applied to assess the potential improvements supersonic through-flow fan technology has over more conventional systems. A fixed geometry supersonic through-flow fan primary inlet was found to have better performance than a conventional inlet design on the basis of total pressure recovery, air flow, aerodynamic drag and size and weight

A supersonic through-flow fan engine airframe integration study

Engine airframe integration effects are investigated for supersonic through-flow fan engines installed on a Mach 3.20 supersonic cruise vehicle. Six different supersonic through-flow fan engine installations covering the effects of engine size, nacelle contour, nacelle placement, and approximate bypass plume effects are presented. The different supersonic through-flow fan installations are compared with a conventional turbine bypass engine configuration on the same basic airframe. The supersonic through-flow fan engine integrations are shown to be comparable to the turbine bypass engine configuration on the basis of installed nacelle wave drag. The supersonic through-flow fan engine airframe integrated vehicles have superior aerodynamic performance on the basis of maximum lift-to-drag ratio than the turbine bypass engine installation over the entire operating Mach number range from 1.10 to 3.20. When approximate bypass plume modeling is included, the supersonic through-flow fan engine configuration shows even larger improvements over the turbine bypass engine configuration

Paper Session III-A - On-Orbit Characterization of Electric Propulsion in Leo Satellites

Because of the current high cost for space experiments on large and small space qualified platforms, alternate methods of space characterization must be explored. Utilizing commercial or military satellites as testbeds for subsystems is a potential platform for small devices. Electric propulsion is a viable and upcoming subsystem that is of high interest to planetary mission engineers as well as commercial satellite developers. The cost of space demonstration, and the risk associated with nonspace tested components, is a major driver in the reluctant admittance into the satellite and space experiment world for electric propulsion. It is proposed that by incorporating small lightweight electric propulsion devices onto small satellites as external or bolt-on experiments, an increase in the number of flight opportunities can occur. Specific problems that will be addressed are spacecraft body interaction, contamination effects, thermal interface problems, power conditioning control electronics, and propulsion feed system interfaces

A non-axisymmetric linearized supersonic wave drag analysis: Mathematical theory

A Mathematical theory is developed to perform the calculations necessary to determine the wave drag for slender bodies of non-circular cross section. The derivations presented in this report are based on extensions to supersonic linearized small perturbation theory. A numerical scheme is presented utilizing Fourier decomposition to compute the pressure coefficient on and about a slender body of arbitrary cross section

IPAC-Inlet Performance Analysis Code

A series of analyses have been developed which permit the calculation of the performance of common inlet designs. The methods presented are useful for determining the inlet weight flows, total pressure recovery, and aerodynamic drag coefficients for given inlet geometric designs. Limited geometric input data is required to use this inlet performance prediction methodology. The analyses presented here may also be used to perform inlet preliminary design studies. The calculated inlet performance parameters may be used in subsequent engine cycle analyses or installed engine performance calculations for existing uninstalled engine data

NPAC-Nozzle Performance Analysis Code

A simple and accurate nozzle performance analysis methodology has been developed. The geometry modeling requirements are minimal and very flexible, thus allowing rapid design evaluations. The solution techniques accurately couple: continuity, momentum, energy, state, and other relations which permit fast and accurate calculations of nozzle gross thrust. The control volume and internal flow analyses are capable of accounting for the effects of: over/under expansion, flow divergence, wall friction, heat transfer, and mass addition/loss across surfaces. The results from the nozzle performance methodology are shown to be in excellent agreement with experimental data for a variety of nozzle designs over a range of operating conditions

Iowa Pasture Management Guide

While there is a great deal of information available on pasture management and utilization, there is no one existing publication that could serve as a comprehensive source of advice on the subject for Iowa farmers. Using feedback from a focus group, a handbook to aid Iowa farmers in pasture management has been prepared

Experimental Investigation of Unsteady Shock Wave Turbulent Boundary Layer Interactions About a Blunt Fin

A series of experiments were performed to investigate the effects of Mach number variation on the characteristics of the unsteady shock wave/turbulent boundary layer interaction generated by a blunt fin. A single blunt fin hemicylindrical leading edge diameter size was used in all of the experiments which covered the Mach number range from 2.0 to 5.0. The measurements in this investigation included surface flow visualization, static and dynamic pressure measurements, both on centerline and off-centerline of the blunt fin axis. Surface flow visualization and static pressure measurements showed that the spatial extent of the shock wave/turbulent boundary layer interaction increased with increasing Mach number. The maximum static pressure, normalized by the incoming static pressure, measured at the peak location in the separated flow region ahead of the blunt fin was found to increase with increasing Mach number. The mean and standard deviations of the fluctuating pressure signals from the dynamic pressure transducers were found to collapse to self-similar distributions as a function of the distance perpendicular to the separation line. The standard deviation of the pressure signals showed initial peaked distribution, with the maximum standard deviation point corresponding to the location of the separation line at Mach number 3.0 to 5.0. At Mach 2.0 the maximum standard deviation point was found to occur significantly upstream of the separation line. The intermittency distributions of the separation shock wave motion were found to be self-similar profiles for all Mach numbers. The intermittent region length was found to increase with Mach number and decrease with interaction sweepback angle. For Mach numbers 3.0 to 5.0 the separation line was found to correspond to high intermittencies or equivalently to the downstream locus of the separation shock wave motion. The Mach 2.0 tests, however, showed that the intermittent region occurs significantly upstream of the separation line. Power spectral densities measured in the intermittent regions were found to have self-similar frequency distributions when compared as functions of a Strouhal number for all Mach numbers and interaction sweepback angles. The maximum zero-crossing frequencies were found to correspond with the peak frequencies in the power spectra measured in the intermittent region

Fall versus Spring Nitrogen Fertilization on Pasture

Iowa livestock producers managing drought-stressed pastures wanted to know if grass-based pastures would recover more quickly or produce more forage by applying nitrogen to pastures in the fall versus their traditional spring application management. A pasture fertilization study was conducted on cool-season grassbased pastures at the Iowa State University Armstrong, Neely-Kinyon, and McNay Research and Demonstration Farms. Urea was hand applied at rates of 0, 22.5, 45, 66.7, and 90 lbs/acre to small plots at each site in October 2000. Some plots received 22.5 and 45 lbs/acre of N at the fall application date as the first half of a split application to total 45 and 90 lb/acre of N. The same N rates were applied to different plots and the remainder of the split application treatments was applied in March 2001. Dry matter yield was determined in mid-May 2001. Yields at the Neely-Kinyon and McNay farms were similar, and slightly higher than those at the Armstrong farm. Yield response to nitrogen application rates was positive and linear for each additional unit of nitrogen applied. The average total increase was about 38% for the first 45 lbsN/acre and about 81% for the 90 lbN/acre rates. There was no statistically significant or consistent relation between pasture yield increase and timing of nitrogen application across the three sites, but there were minor differences among sites. The trend, however, indicated that greater yields frequently were obtained from the early spring application treatments. Data was not collected to assess forage nutritive quality or stand density, however, both could be of value and importance to the long-term sustainability of a foragelivestock enterprise. These results indicate that for the period studied, there was no consistent advantage in applying nitrogen fertilizer to grass-based pastures in late fall or splitting the total application between fall and spring as compared to making traditional spring nitrogen applications

Rotary balance data for a typical single-engine general aviation design for an angle-of-attack range of 20 to 90 deg. 3: Influence of control deflection on predicted model D spin modes

The influence of control deflections on the rotational flow aerodynamics and on predicted spin modes is discussed for a 1/6-scale general aviation airplane model. The model was tested for various control settings at both zero and ten degree sideslip angles. Data were measured, using a rotary balance, over an angle-of-attack range of 30 deg to 90 deg, and for clockwise and counter-clockwise rotations covering an omegab/2V range of 0 to 0.5