Abstract:The metal fueled steam Rankine cycle has been successfully applied to Unmanned Underwater Vehicles. However, the suitable turbine configuration is yet to be determined for this particular application. In this paper, the mean-line design approach based on the existing empirical correlations is first described. The corresponding partial admission axial and radial inflow turbines are then preliminarily designed. To assess the performance of designed turbines, the three-dimensional Computational Fluid Dynamics (CFD) simulations and steady-state structural analysis are performed. The results show that axial turbines are more compact than radial inflow turbines at the same output power. In addition, since radial inflow turbines can reduce the exit energy loss, this benefit substantially offsets the increment of the rotor losses created by the low speed ratios and supersonic rotor inlet velocity. On the contrary, due to the large volume of dead gas and strong transient effects caused by the high rotor blade length of radial inflow turbines, the overall performance between axial and radial inflow turbines is comparable (within 4%). However, the strength of radial inflow turbines is slightly superior because of lower blade inlet height and outlet hub radius. This paper confirms that the axial turbine is the optimal configuration for underwater vehicles in terms of size, aerodynamics and structural performance.Keywords: partial admission; turbine comparison; computational fluid dynamics; underwater vehicles; loss breakdown
For many years, Concepts NREC has offered a course on axial and radial turbine design for practicing engineers and students of turbomachinery presented by the authors of this volume. The present book has been developed from that. It is, however, very much more than a simple reprinting of the course notes. Great effort has been made to produce a book that presents a complete, coherent, and up-to-date account of the design and analysis of axial and radial turbines. Overview
A thorough survey and analysis of investigations into instabilities in axial and centrifugal compressors provides an up-to-date understanding of stall-free, surge-free operation for users, and is a resource for engineers and scientists working in compressor design. This book is suggested for compressor designers and users who appreciate the need for understandable surge lines for a wide range of stall-free, surge-free operation, as well as those who wish to gain an up-to-date understanding of the field. Overview
All versions of the engine consist of two sections that can be easily separated for maintenance: a gas generator supplies hot pressurized gas to a free power turbine. The starter has to accelerate only the gas generator, making the engine easy to start, particularly in cold weather. Air enters the gas-generator through an inlet screen into the low-pressure axial compressor. This has three stages on small and medium versions of the engine and four stages on large versions. The air then flows into a single-stage centrifugal compressor, through a folded annular combustion chamber, and finally through a single-stage turbine that powers the compressors at about 45,000 rpm. Hot gas from the gas generator flows into the power turbine, which turns at about 30,000 rpm. It has one stage on the small engines and two stages on the medium and large ones. For turboprop use, this powers a two-stage planetary output reduction gearbox, which turns the propeller at a speed of 1,900 to 2,200 rpm. The exhaust gas then escapes through two side-mounted ducts in the power turbine housing. The turbines are concentric with the combustion chamber, reducing overall length.