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Flows in the first stages of axial compressors are subject to a number of unsteady effects which are not generally taken into account in standard investigations, e.g. transition under the influence of impinging wakes as well as that of downstream potential effects, or the influence of unsteady blade row interactions. For numerical studies of these phenomena, usually, simplifications are made to the test case in question. These simplifications include domain scaling, quasi-unsteady modeling, or modeling assumptions regarding boundary layer development, like wall functions; and their impact on the final result can be quite high. This paper is concerned with the investigation of unsteady blade row interactions in a 4.5 stage research compressor without any of these simplifications. To this end, the whole annulus of the first two stages of the compressor was meshed and unsteady RANS simulations were carried out at two different operating points. Spatial and temporal resolutions were fine enough to allow the investigation of transitional phenomena on the blade surface using an integral multi-mode transition model. For each operating point, one revolution was recorded after computations reached a periodic state. Examination of the boundary layer parameters shows that transition plays a considerable role for the first two compressor stages which were investigated in more detail. It was evident that the development of the blade boundary layer depends not only on incoming wakes from upstream blade rows; the precise transition location is also highly dependent on the potential effect of downstream blade rows.

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The two dimensional flow of an electrorheological fluid in a concentric cylinder, Couette type apparatus is investigated at different inter-plate speeds, voltages and axial pressure gradients. Test results at low, but realistic, loading conditions correlate with Bingham plastic computer fluid dynamics (CFD) package predictions, at each field strength. The package had been pre verified against an analytical solution for the same flow field. In all cases the liquid is taken to be isothermal. Indications are that the rate of throughflow should not interfere severely with the voltage set magnitude of torque transmission. Hence the cooling of slipping clutches by through flow can be contemplated. At present the investigation covers only the case of one stationary and one moving plate with no heat transfer or centrifugal terms.

The growing demand of low noise civil aircraft brings out technical challenges which require the application of computational aeroacoustics (CAA) methods within the development process of jet engines. This paper focuses on the simulation of exhaust jet noise based on a realistic turbofan lobe-forced mixer configuration and operating condition. The present study aims at showing the ability of a Ffowcs Williams-Hawkings (FW-H) approach for solving the acoustical sources of a complex turbulent (sheared) flow and for predicting the far field (broadband) noise based on a Detached Eddy Simulation (DES). The evaluation of the prediction results by comparing with benchmark data yield some general guidelines given for model improvements.