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Publication Title | RADIAL-FLOW WAVE ROTOR CONCEPTS, UNCONVENTIONAL DESIGNS

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Proceedings of IMECE04 2004 ASME International Mechanical Engineering Congress November 13–19, 2004, Anaheim, California USA
IMECE2004-59022 RADIAL-FLOW WAVE ROTOR CONCEPTS, UNCONVENTIONAL DESIGNS AND APPLICATIONS
Janusz Piechna
Warsaw University of Technology Institute of Aeronautics and Applied Mechanics 24 Nowowiejska Str.
Warsaw, Poland
Phone: +48 (22) 660 7768
Fax: +48 (22) 622 0901
Email: jpie@meil.pw.edu.pl
Florin Iancu
Michigan State University Mechanical Engineering Department 2500 Engineering Building
East Lansing, Michigan 48824-1226 Phone: +1 (517) 432 1102
Fax: +1 (517) 353 1750
Email: ihuin@egr.msu.edu
ABSTRACT
Wave rotor technology has shown a significant potential for performance improvement of thermodynamic cycles. The wave rotor is an unsteady flow machine that utilizes shock waves to transfer energy from a high energy fluid to a low energy fluid, increasing both temperature and pressure of the low energy fluid. While several different configurations of mainly axial-flow wave rotors have been studied in the past, its four-port version with straight channels has been used most widely. During the past century, extensive experimental and numerical efforts have been performed on such conventional designs. This study introduces a new radial-flow configuration that can be employed in several novel designs. Advantages and challenges of such designs are outlined. Feasible implementations of these arrangements into gas turbine engines are shown and a new rotor speed controlling system is described, too.
Keywords: radial wave rotor, comprex, internal combustion wave rotor, shock waves, gas turbine,
Pezhman Akbari
Michigan State University Mechanical Engineering Department 2500 Engineering Building
East Lansing, Michigan 48824-1226 Phone: +1 (517) 432 1102
Fax: +1 (517) 353 1750
Email: akbari@egr.msu.edu
Norbert Müller
Michigan State University Mechanical Engineering Department 2455 Engineering Building East Lansing, Michigan 48824-1226 Phone: +1 (517) 432 9139
Fax: +1 (347) 412 7848
Email: mueller@egr.msu.edu
INTRODUCTION
The potential of unsteady-flow wave machines for performance enhancement of thermodynamic cycles has been recognized, but often neglected until recently. Shock tubes, shock tunnels, pressure exchangers, pulse combustors, pulse detonation engines, and wave rotors are the best-known wave devices developed so far. Different to reciprocating machines and turbomachinery that employ mechanical parts like pistons and blades to accomplish compression or expansion processes, unsteady-flow devices utilize compression and expansion waves for various applications. It has been proved that for the same inlet and outlet Mach numbers the pressure gain in time- dependent flow devices can be much greater than in steady flow devices [1, 2], which may be a driving reason for using unsteady wave machines. Their geometry can be very simple like that of a straight tube, since the mechanical parts only house and control the wave process. Hence their manufacturing cost can be low. In this work attention is given to wave rotor machines.
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Copyright © 2004 by ASME

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MicroAD: This research and pdf compilation was sponsored Infinity Turbine Turn your waste heat into energy to save on grid based power or sell back to the grid Organic Rankine Cycle utilizes waste heat to make power. Infinity Turbine Waste Heat to Power Solutions

RADIAL-OUTFLOW-TURBINE: In a radial outflow turbine the organic fluid enters the disk axially in its center and expands radially through a series of stages mounted on the single disk. At the discharge of the last rotor row the flow passes through a radial diffuser and is then conveyed to the recuperator and or condensa- tion section of the system, through the discharge volute. In the early 20th century, Parsons Siemens and Ljungstrom developed the first steam based radial outflow turbines. These early model turbines required a large number of stages. For very high enthalpy drop fluids, such as steam, a single-disk/multi stage configuration was therefore deemed not suitable due to the very large diameter disk necessary to accommodate all the required stages. No further development of the radial outflow turbines oc- curred, as they were phased out for steam applications by axial turbines.

The Geothermal Radial Outflow Turbine: An innovative turbine configuration for geothermal applica- tions was developed by the Italian turbine manufacturer EXERGY. The technology, known as the organic radial outflow turbine was designed, engineered, manufactured and tested in Italy. A 1 MWe geothermal organic Rankine cycle (ORC) equipped with the EXERGY radial outflow turbine has been in operation since early 2013. The radial outflow turbine is a new type of turbine that have the potential to increase the geothermal binary power plants ef- ficiency by increasing the turbine efficiency. The operational results has been positive and demonstrates the viability of the technology and the possibility to develop it for bigger sizes.

Preliminary Design and Off-Design Analysis of a Radial Outflow Turbine for Organic Rankine Cycles: Recently, the advantages of radial outflow turbines have been outstanding in various operating conditions of the organic Rankine cycle. However, there are only a few studies of such turbines, and information on the design procedure is insufficient. The turbine target performance could be achieved by fine-tuning the blade angle of the nozzle exit. In addition, performance evaluation of the turbine against off-design conditions was performed. Ranges of velocity ratio, loading coefficient, and flow coefficient that can expect high efficiency were proposed through the off-design analysis of the turbine.

Study on applicability of radial-outflow turbine type for 3 MW WHR organic Rankine cycle: The article presents the results of study on the reasonability of using radial-outflow turbines in ORC. Peculiarities of radial-outflow turbine design utilizing modern design technologies and application to ORC was considered in the first part of the paper. For this particular cycle design, turbines of radial-outflow type were chosen. Their application enables the increase of mechanical output power by 11 percent compared to original radial-inflow turbines.

LOSS GENERATION IN RADIAL OUTFLOW STEAM TURBINE CASCADES: Small high-speed technology based radial outflow steam turbines are characterised by ultra-low aspect ratios, which can lead to rapidly growing secondary losses. The prelimi- nary evaluation of turbine performance is usually based on axial turbine loss predictions, which can be a source of error. The main objectives of this work are to find out how the losses are generated in radial outflow turbines when the aspect ratio is markedly below unity and how accurately axial turbine loss models can predict the trends. To achieve these objectives, a radial outflow turbine cascade having a blade shape and aspect ratios comparable with a prototype machine is examined. As a result of the study, it is suggested that for the examined radial outflow cascade the axial turbine loss correlations can predict the trends reasonably well. The rapidly increasing secondary losses are connected to the merging of secondary structures and also incidence at off-design.

PRELIMINARY DESIGN OF RADIAL-INFLOW TURBINES FOR ORGANIC RANKINE CYCLE POWER SYSTEMS CONSIDERING PERFORMANCE AND MANUFACTURABILITY ASPECTS: In order to make organic Rankine cycle power systems economically feasible, it is essential to find a reasonable trade-off between the performance and the initial cost of system. In order to show its relevance in a practical application, the method is applied to two radial-inflow turbines cases: a state-of-the-art turbine using air and a turbine using the working fluid Novec 649 for a heat recovery application. The results indicate that there exists a trade-off between turbine performance and manufacturability, and that it is possible to develop turbine solutions with similar values of efficiency with improved manufacturability indicator by up to 14 to 15 percent.

DESIGN AND FLOW ANALYSIS OF RADIAL AND MIXED FLOW TURBINE VOLUTES: Radial and mixed flow turbines which are an important component of a turbocharger consist essentially of a volute, a rotor and a diffuser. Vaneless volute turbines, which have reasonable performance and low cost, are the most used in turbochargers for automotive engines. Care has to be done in the design of the volute, whose function is to convert a part of the engine exhaust gas energy into kinetic energy and direct the flow towards the rotor inlet at an appropriate flow angle with reduced losses.

An Exploration of Radial Flow on a Rotating Blade in Retreating Blade Stall: The nature of radial flow during retreating blade stall on a two-bladed teetering rotor with cyclic pitch variation is investigated using laser sheet visualization and particle image velocimetry in a low-speed wind tunnel. The velocity field above the retreating blade at 270◦ azimuth shows the expected development of a radially directed jet layer close to the blade surface in the otherwise separated flow region. This jet is observed to break up into discrete structures, limiting the spanwise growth of the radial velocity in the jet layer. The discrete structures are shown to derive their vorticity from the “radial jet” layer near the surface, rather than from the freestream at the edge of the separated region. The separation line determined using velocity data shows the expected spanwise variation. The results of this study are also correlated in a limited range of extrapolation to the phenomena encountered on a full-scale horizontal axis wind turbine in yaw.

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