Modification of the FanWing concept intended for the use at higher speeds of flight (over 20 m/s) is numerically analyzed. The principle of operation, basic aerodynamic characteristics, and the features in untypical flight situation (autorotation) are described and explained.

Many groups of researchers have focused on the design of micro turbine engines in recent years. Since turbo-component efficiency becomes very low due to the downsizing effect, an important problem arises of how to obtain thermal efficiency high enough to produce the positive power required. The micro wave rotor is expected to be applied for the improvement of the performance of ultra micro gas turbines, increasing the cycle pressure ratio. Wave rotors can also be built in another configuration. Applying only a combustion chamber and using oblique blades to form the rotor cells, net power can be taken from the rotor. In that way, the use in a micro scale of an inefficient turbo unit can be omitted. Such a solution in a form of wave engine was developed and practically realised by Weber [ 15] and Pearson [8], [9], [ IO] in centimetre scale. Conventional construction of wave engines in a form of wave rotor can not be directly realized in MEMS technology. The new idea of a wave disk developed by Piechna, Akbari, Iancu,and Mueller [II] and independently by Nagashima and Okamoto [7] gives the possibility of easy implementation of the wave engine idea in MEMS technology. In the proposed solution, the wave disk plays the role of an active compressiondecompression unit and torque generator. Appropriate port geometry with oblique blades forming the disk channels generates torque. The engine disk rotates with a speed much lower than the conventional turbo-unit that simplifies the bearing problem. Also, the construction of electric generator can be simpler. The paper presents the proposed flow schemes, thermodynamic cycle, exemplary engine construction and some results of simulation of the MEMS wave engine using the wave disk.

The two dimensional steady and unsteady flow field at midspan in a low speed axial flow compressor stage has been investigated experimentally, using two systems, based on totally different principles: a 2-sensor fast response straight and 90° triple split fiber probes (TSFP) and two dimensional LOA system with an emphasis on the interaction of the inlet guide vane (IGY) wake with the rotor flow field. To account for the uniformity of the rotor absolute inlet flow field, measurements has been made at eight tangential locations in the absolute frame equally spaced over one IGY pitch. The time resolved investigation, done by TSFP and LOA allows to presenting velocity fields, flow angles and turbulence data at different [GY-rotor positions during one blade passing period. The velocity measurements are decomposed into a time averaged velocity, a periodic velocity component and a unresolved velocity component. Using two measurement systems, one being intrusive and the other non-intrusive, in the same complex flow field, gives the opportunity for a critical comparison of results and opens the view for further improvements. Averaging these results, enabled also comparison with the pneumatic five-hole probe measurement.

The paper presents experimental investigations of pressure fluctuations near the tip clearance region of the rotor blades of the axial-flow low-speed compressor stage in stable and unstable parts of the overall performance characteristic. In this investigation, unsteady pressure was measured with the use of high frequency pressure transducers mounted on the casing wall of rotor passage. The pressure signals and their frequency characteristics were analyzed during the steady-state processes, before the rotating stall, during the transition from the steady-state process to the rotating stall, and during a stabilized phenomenon of low-frequency rotating stall. As the operating point moves to the unstable region of flow characteristic, an inception of the rotating stall can be observed, which rotates with a speed of about 41.4% of the rotor speed. The results of this study confirm that in the low-speed axial compressor stage operating in a rotating stall regime there appears one stall cell that spreads over to adjacent rotor blade channels. As the flow rate is reduced further, the frequency of the rotating stall decreased to 34.8% of the rotor speed and the number of blade channels with the stall cell increases.

This paper investigated the problems and impacts of transient flow in pipeline systems due to pump power failure. The impact of different protection devices was presented to assure surge protection for the pipeline system. A model via Bent-ley HAMMER V8.0 Edition was employed to analyse and simulate hydraulic transients in the pipeline system, and protec-tion alternatives were studied.

Surge protection included using only an air vessel, using an air vessel and two surge tanks, and employing five air ves-sels and vacuum breaker. The obtained results for pressures, heads, and cavitation along the pipeline system were graph-ically presented for various operating conditions. Using five air vessels with vacuum breaker valve as surge protection proved to be more effective and economical against pump power failure.

Changing the flow density did not have a significant impact on the pressures.

For protection with an air vessel; it was concluded that the value 40% of the original diameter for inlet pipe diameter of air vessel, and the value of 2/3 of original pipe diameter were critical values for the transient pressures. Cast iron pipes proved to be the best pipe material for all studied volumes of the air vessel.

For protection with an air vessel and two surge tanks; as the inlet pipe diameters increased the maximum pressures in-creased and the minimum pressures decreased.

Regression analyses were performed obtaining equations to predict the pressures according to the inlet pipe diameter, the area of surge tank, and the pipe diameter.