Saab Automobile AB

About: Saab Automobile AB is a based out in . It is known for research contribution in the topics: Radar & Signal. The organization has 760 authors who have published 890 publications receiving 11811 citations.

Predictions of the Performance of a Radial Turbine with Different Modeling Approaches: Comparison of the Results from 1-D and 3-D CFD

Abstract: In this paper, the performance of a radial turbine working under pulsatile flow conditions is computed with two different modeling approaches, time resolved 1-dimensional (1-D) and 3-dimensional (3-D) CFD. The 1-D modeling approach is based on measured turbine maps which are used to compute the mass flow rate and work output from the turbine for a given expansion ratio and temperature at the inlet. The map is measured under non-pulsatile flow conditions, and in the 1-D method the turbine is treated as being a quasi-stationary flow device. In the 3-D CFD approach, a Large Eddy Simulation (LES) turbulence approach is used. The objective of LES is to explicitly compute the large scales of the turbulence while modeling the effects of the unresolved scales. Three different cases are considered, where the simplest case only consist of the turbine and the most complex case consist of an exhaust manifold and the turbine. Both time resolved data, such as pressure ratio, temperature and shaft torque and time mean data from the two different modeling approaches are compared. The results show that the computed time mean shaft power differs between the two different modeling approaches with as much as 100%. Since the considered operation point for the engine in this study is 1500 rpm with wide open throttle, the turbine operates in an area where the turbine map is extrapolated. Only by using a few operation points from CFD to extend the map, an improvement is achieved for the 1-D results, but still the deviation is large. Also, the pressure ratio and temperature drop over the turbine differs for the used modeling approaches. The causes for the deviations are assessed and discussed to get a better understanding of eventually limitations of the 1-D modeling approach.

Issues in connection to the prediction of strain localization in metal sheets

Abstract: The current paper deals with the prediction of strain localization in metal sheets. Especially the effect of strain rate dependency on the necking phenomenon is treated. The ability of FEM to predict strain localization during simulations of sheet forming operations is investigated. An approach for the determination of the strain rate material parameters, based on an experimentally determined FLD0, is suggested. The current approach is demonstrated for three sheet materials, and from the results the approach can be judged as promising.

Device for linear displacement of a plane optical image in its own plane

Abstract: An optical apparatus for displaying spectral images is disclosed, the device including two reflecting planes fixed at right angles to each other but displaceable with respect to an image plane to permit a scanning of an optical image. Both reflecting planes are at a 45* angle with the image plane, and the line of intersection of the two reflecting planes oscillates in a direction which is transverse to the line of intersection of the reflecting planes, whereby the image is scanned sinusoidally past an opening in the image plane. A light-sensitive element behind the opening transforms the light into an electrical signal which corresponds in amplitude to the light intensity and which can be displayed on an oscilloscope. A sensing means tracks the swing movement, generating a signal which may be used as one coordinate axis of the oscilloscope display. A phase correction network is located between the sensing means and the oscilloscope so that the correct phase relationship between the oscillating swing and the display may be obtained.

Device for a launcher on air vehicle

Abstract: A device at a launcher at an air vehicle for detachably carrying and guiding a missile or the like is shown. The launcher comprises means for detachably carrying the missile and means for guiding the missile in the longitudinal direction of the launcher. The latter comprises a first profile element (2) secured in the launcher and a second profile element (4) secured in the missile, which profile elements are arranged to interact in order to admit a free mutual movement in the longitudinal direction of the launcher, while movement in lateral directions is limited. The device according to the invention is characterized particularly in that it comprises a profile plate (7) and a number of relatively thin shims (8), the profile plate (7) and shims (8) being arranged securable in the first profile element (2) to so limit by means of an appropriate number of shims (8) the mutual movement of the first (2) and the second (4) profile element in the load carrying direction across the longitudinal direction of the launcher that the required allowance between the profile elements (2, 4) for mutual movability of the profile elements in the longitudinal direction of the launcher is maintained.