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Abstract

This paper comprises description of the turbo engine and evaluation of its analytical model. The analytical model was created to establish a benchmark for further evaluation of a wave rotor combustor (at constant volume). The wave rotor combustor concept was presented and discussed. Advantages of combustion at constant volume were described as well as the basic turbo engine updates required to reflect pulse combustor application. The calculation results for analytical model of a basic engine, and that equipped with pulse combustor are included in this paper. The paper describes the required changes in the engine structure and construction and the estimated thermodynamic improvements. Axial-type pulse multi-chamber combustion unit increasing the pressure and temperature of gases requires a special additional turbine utilizing additional energy and forming the interface between the standard compressor-turbine unit. Performance calculations done for an existing GTD-350 engine showed that constant-volume combustion process is valuable.

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Authors and Affiliations

Damian Łapiński
Janusz Piechna
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Abstract

This paper presents the results of numerical analysis of aerodynamic characteristics of a sports car equipped with movable aerodynamic elements. The effects of size, shape, position, angle of inclination of the moving flaps on the aerodynamic downforce and aerodynamic drag forces acting on the vehicle were investigated. The calculations were performed with the help of the ANSYS-Fluent CFD software. The transient flow of incompressible fluid around the car body with moving flaps, with modeled turbulence (model Spalart-Allmaras or SAS), was simulated. The paper presents examples of effective flap configuration, and the example of configuration which does not generate aerodynamic downforce. One compares the change in the forces generated at different angles of flap opening, pressure distribution, and visualization of streamlines around the body. There are shown the physical reasons for the observed abnormal characteristics of some flap configurations. The results of calculations are presented in the form of pressure contours, pathlines, and force changes in the function of the angle of flap rotation. There is also presented estimated practical suitability of particular flap configurations for controlling the high-speed car stability and performance.

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Authors and Affiliations

Tomasz Janson
Janusz Piechna

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Abstract

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.
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Authors and Affiliations

Janusz R. Piechna
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Abstract

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.
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Authors and Affiliations

Andrzej Witkowski
Mirosław Majkut
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Abstract

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.

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Authors and Affiliations

Alaa N. El-Hazek
Menna F. Ahmed
Neveen Abdel-Mageed Badawy

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