Small axial compressor technology, volume 1

A scaled single-stage, highly-loaded, axial-flow transonic compressor was tested at speeds from 70 to 110% design equivalent speed to evaluate the effects of scaling compromises and the individual and combined effects of rotor tip running clearance and rotor shroud casing treatment on the overall and blade element performance. At design speed and 1% tip clearance the stage demonstrated an efficiency of 83.2% at 96.4% design flow and a pressure ratio of 1.865. Casing treatment increased design speed surge margin 2.0 points to 12.8%. Overall performance was essentially unchanged. An increase in rotor running clearance to 2.2%, with smooth casing, reduced design speed peak efficiency 5.7 points, flow by 7.4%, pressure ratio to 1.740, and surge margin to 5.4%. Reinstalling casing treatment regained 3.5 points in design speed peak efficiency, 4.7% flow, increased pressure ratio to 1.800 and surge margin to 8.7%

A model for the submarine depthkeeping team

The most difficult task the depthkeeping team must face occurs during periscope-depth operations during which they may be required to maintain a submarine several hundred feet long within a foot of ordered depth and within one-half degree of ordered pitch. The difficulty is compounded by the facts that wave generated forces are extremely high, depth and pitch signals are very noisy and submarine speed is such that overall dynamics are slow. A mathematical simulation of the depthkeeping team based on the optimal control models is described. A solution of the optimal team control problem with an output control restriction (limited display to each controller) is presented

Pilot cryo tunnel: Attachments, seals, and insulation

Several different tests are described which simulated the actual configuration of a cryogenic wind tunnel operating at pressures up to 5 atmospheres (507 kPa) and temperatures from -320 F (78K) to 120 F (322K) in order to determine compatible bolting, adequate sealing, and effective insulating materials. The evaluation of flange attachments (continuous threaded studs) considered bolting based on compatible flanges, attachment materials, and prescribed bolt elongations. Various types of seals and seal configurations were studied to determine suitability and reusability under the imposed pressure and temperature loadings. The temperature profile was established for several materials used for structural supports

Southwest Research Institute assistance to NASA in biomedical areas of the technology utilization program Quarterly progress report, 1 Jul. - 30 Sep. 1968

Southwest Research Institute activites in NASA technology utilization program for biomedical use, 1 Jul. - 30 Sep. 196

Southwest Research Institute assistance to NASA in biomedical areas of the technology utilization program Cumulative quarterly report, 1 Apr. - 30 Jun. 1968

Biomedical applications of NASA science and technolog

Oviposition Sites and Emergence Habitats of 13-Year Periodical Cicadas (Brood XIX) in Eastern Virginia

While much research has been done on periodical cicadas, apparently no quantitative studies have been carried out to determine the vegetational structure of periodical cicada brood emergence sites or oviposition sites. We determined large tree and small tree densities and dominance in five forest stands which experienced high densities of Brood XIX cicada emergence in 1998. Paired observations were made at one of these sites to determine whether there was a preference for egg deposition in woodland edges versus the forest interior. A list was compiled of all the tree species which exhibited evidence of egg deposition. We found that the canopies of emergence sites can be dominated by loblolly pine (Pinus taeda), oaks (Quercus spp.), sweetgum (Liquidambar styraciflua), hickories (Carya spp.), and beech (Fagus grandifolia), with red maple (Acer rubrum) or holly (Ilex opaca) important in the understory. The abundance of loblolly pine, the only common species in which no egg deposition was found, suggests that 13 years earlier, periodical cicadas found a sufficient number of other tree species in which to deposit their eggs. This also suggests that the roots of pine trees might be capable of sustaining the cicada nymphs. Brood XIX cicadas showed a significant preference for depositing their eggs on twigs on forest edges rather than depositing on shaded twigs in the forest interior

Application of holography to flow visualization within rotating compressor blade row

Two holographic interblade row flow visualization systems were designed to determine the three-dimensional shock patterns and velocity distributions within the rotating blade row of a transonic fan rotor, utilizing the techniques of pulsed laser transmission holography. Both single- and double-exposure bright field holograms and dark field scattered-light holograms were successfully recorded. Two plastic windows were installed in the rotor tip casing and outer casing forward of the rotor to view the rotor blade passage. The viewing angle allowed detailed investigation of the leading edge shocks and shocks in the midspan damper area; limited details of the trailing edge shocks also were visible. A technique was devised for interpreting the reconstructed holograms by constructing three dimensional models that allowed identification of the major shock systems. The models compared favorably with theoretical predictions and results of the overall and blade element data. Most of the holograms were made using the rapid double-pulse technique