Experimental study of surface pressures induced on a flat plate and a body of revolution by various dual jet configurations

The effect of the angle of a jet to a crossflow, the performance of dual jet configurations, and a jet injected from a body of revolution as opposed to a flat plate were investigated during experiments conducted in the 7x10 tunnel at NASA Ames at Velocities from 14.5 m/sec to 35.8 m/sec (47.6 to 117.4 ft/sec.). Pressure distributions are presented for single and dual jets over a range of velocity ratios from 2 to 10, spacings from 2 to 6 diameters and injection angles of 90, 75, 60, and 105 degrees. For the body of revolution tests, the ratio of the jet to body diameters was set as large (1/2) in order to be more representative of V/STOL aircraft applications. Flat plate tests involved dual jets both aligned and in side by side configurations. The effects of the various parameters and the differences between the axisymmetric and planar body geometrics on the nature, size, shape, and strength of the interaction regions on the body surfaces are shown. Some flowfield measurements are also presented, and it is shown that a simple analysis is capable of predicting the trajectories of the jets

Heat-transfer and pressure distributions for laminar separated flows downstream of rearward-facing steps with and without mass suction

Heat-transfer and pressure distributions were measured for laminar separated flows downstream of rearward-facing steps with and without mass suction. The flow conditions were such that the boundary-layer thickness was comparable to or larger than the step height. For both suction and no-suction cases, an increase in the step height resulted in a sharp decrease in the initial heat-transfer rates behind the step. Downstream, however, the heat transfer gradually recovered back to less than or near attached-flow values. Mass suction from the step base area increased the local heat-transfer rates; however, this effect was relatively weak for the laminar flows considered. Even removal of the entire approaching boundary layer raised the post-step heat-transfer rates only about 10 percent above the flatplate values. Post-step pressure distributions were found to depend on the entrainment conditions at separation. In the case of the solid-faced step, a sharp pressure drop behind the step was followed by a very short plateau and relatively fast recompression. For the slotted-step connected to a large plenum but without suction, the pressure drop at the base was much smaller and the downstream recompression more gradual than that for solid-faced step

Rearward-facing steps in laminar supersonic flows with and without suction

An experimental investigation of heat-transfer and pressure distributions within regions of laminar separated flows produced by two-dimensional rearward-facing steps has been carried out at freestream Mach numbers of around 4 in the range of step height-to-boundary layer thickness varying from 0.1 to 2.4. With no suction from the separated area, the ratio of the maximum post-step heat transfer to the attached-flow values was less than unity. The maximum heating-rate region was located far downstream of the reattachment plate stagnation point. Mass suction from the separated area increased the local heating rates, this effect was however relatively weak for purely laminar flow conditions and the competing effect of the step height clearly predominated. At step heights comparable with boundary-layer thickness, even removing the entire approaching boundary layer was not sufficient to raise the post-step heating rates above the flat-plate values

PARAS program: Phased array radio astronomy from space

An orbiting radio telescope is proposed which, when operated in a Very Long Baseline Interferometry (VLBLI) scheme, would allow higher (than currently available) angular resolution and dynamic range in the maps, and the ability of observing rapidly changing astronomical sources. Using a passive phases array technology, the proposed design consists of 656 hexagonal modules forming a 150 meter diameter dish. Each observatory module is largely autonomous, having its own photovoltaic power supply and low-noise receiver and processor for phase shifting. The signals received by the modules are channeled via fiber optics to the central control computer in the central bus module. After processing and multiplexing, the data is transmitted to telemetry stations on the ground. The truss frame supporting each observatory pane is a hybrid structure consisting of a bottom graphite/epoxy tubular triangle and rigidized inflatable Kevlar tubes connecting the top observatory panel and bottom triangle. Attitude control and stationkeeping functions are performed by a system of momentum wheels in the bus and four propulsion modules located at the compass points on the periphery of the observatory dish. Each propulsion module has four monopropellant thrusters and six hydrazine arcjets, the latter supported by a nuclear reactor. The total mass of the spacecraft is 22,060 kg

FEA simulation of the biomechanical structure overload in the university campus planting

FEM investigation of the branch collapse is provided for the huge healthy chestnut tree. Strong wind gust (24 m/s) is assumed. Thus, simulation has as engineering so methodic value to improve the FEM-teaching of students. The geometry was recovered by the photos and sketches. It includes roots, trunk, branch and conditional crown. Static simulation is provided both in the linear formulation and in the geometrically nonlinear one. Branch under109 goes bending with a moderate portion of the twisting. Near uniform stress dispensation is stated along the branch. There are no stress concentrators at all. The trunk-branch junction is steady enough and self-optimized. The branch has grown with the implementation of the idea of „equal-strength console”. Transforming of the branch section provides constant stress level along the branch. Collapse is caused by a severe accidental wind gust. Work stresses have exceeded twice the allowable level (16 MPa) along the main part of the branch. The tree should be taken as an example of an effective bionic design for the load-bearing system. Simulation confirms the effect of self-reinforcing during tree growth. Tree simulation may be methodologically useful. It is understandable and interesting for students

Parthenon faсade fea simulation as system of freely piled solids joined by gravity and friction

Paper concerns to contact task simulation by FEA for “freely piled solids” systems. It may be different dry masonries. The antique façade of the Parthenon temple is taken for simulation as an example. Marble drums and blocks are held together only by friction and gravity. Multiplicity and variability of contact pressure patterns inside columns are disclosed. Surface compression concentrators (SCC) between echinus and top drums are revealed. Such concentrators are proved to be safe for antique marble load-bearing structures. Contact sliding in the column joints is investigated. Slipping localization on the top and bottom of columns is pointed out as a predictor of the uncontrolled movement and falling in the case of the façade inclination. The usefulness of „piled solids” contact tasks for FEA-training of students is stated

‘You probably won’t notice any symptoms’ Blood pressure in pregnancy:discourses of contested expertise in an era of self-care and responsibilisation

Pregnancy is not a disease or illness, but requires clinical surveillance as life-threatening complications can develop. Preeclampsia, one such potentially serious complication, puts both mother and baby at risk. Self-monitoring blood pressure in the general population is well established, and its potential in pregnancy is currently being explored. In the context of self-monitoring, the information and guidance given to women regarding hypertension, and the literature they themselves seek out during pregnancy, are vital to perceptions of disease risk and subsequent responses to, and management of, any symptoms. Drawing on online, offline, official, and unofficial sources of information, discourses are examined to provide analysis of how self-responsibilization is reflected in contemporary information, advice, and guidance drawn from multiple sources. A paradox emerges between the paternalistic and lay discourses that seek to challenge and regain control. Findings are discussed in the context of Foucault’s governmentality and medical power