Waste Heat to Energy ORC Information Series
Infinity Turbine Search Presents: search was updated real-time via Filemaker on:Infinity Turbine Search Presents: | Return to Search List
Search Completed | Title | Turbine Blade Aerodynamics
Original File Name Searched: turbine-blade-aerodynamics.pdf | Google It | Yahoo | Bing
Text | Turbine Blade Aerodynamics | 001
Turbine Blade Aerodynamics
Louisiana State University CEBA 1419B, Mechanical Engineering Department Baton Rouge, LA 70803
phone: (225) 578-5809 email: firstname.lastname@example.org
The aerodynamics of the flow in a turbine stage (stator/rotor) is rather complex and is still the subject of many ongoing research activities in the gas turbine community. The flow is inherently three dimensional due to the vane/blade passage geometry with features such as twisting of the vane/blade along the span, clearance between the blade tip and the shroud, film cooling holes, and end wall contouring1. The passage flow is characterized by boundary layer effects, secondary flows generated by the passage pressure gradients, and vortical flow structures such as the leading edge horse-shoe vortices, tip-leakage flow vortices, and corner vortices2. The effects of centrifugal-buoyancy, shock- boundary layer interaction, and flow interactions between the stator and rotor rows complicate the passage flow field even further. Along the end walls, the flow structure is strongly three- dimensional with the passage vortex and coolant injection on the hub side and the tip-leakage vortex on the tip side. In the mid- span regions located away from the passage walls and outside the viscous shear layer, the radial flow is almost negligible and the flow is effectively two dimensional. The fluid dynamics in this region can then be based on two dimensional planar cascade flow studies without any significant loss of information. The three dimensional complex flow structures near the hub endwall region and in the blade tip-shroud clearance have been simulated in annular vane/blade passages with and without rotating blade row3. Studies of the complex end-wall flows have also been performed in stationary cascades with three dimensional airfoil shapes4. The qualitative features of the passage flows, which comprise mainly of the passage crossflow (flow from the pressure side of vane/blade to suction side of adjacent vane/blade) and vortical flows induced by the leading edge, the corners, and the injected coolant flows have been studied in detail in stationary cascades and are considered to be similar in both stationary and rotating blade rows. The primary difference in the secondary flow structure between the blade passage and vane passage is that the vortical flows and cross flows in the blade passage are stronger because of higher turning of the flows along the blade passage. Secondary flows are the major source of aerodynamic losses, which account for 35%-40% of all losses5 and thermal loading in the turbine passage, and thus require special considerations by the turbine designers.
The primary objectives of this chapter are to present and analyze the features of the flow field in the turbine vane/blade passage near the hub endwall and mid-span locations of the blade. Toward this effort, reported measurements and computations of pressure, velocity distributions, flow turning angles, turbulence intensity, and vorticity distributions in the cascade test section are presented. Recent efforts to reduce the secondary flows by structural modifications in the passage are discussed. In this chapter, basic fluid dynamic principles and mathematical models of the flow in the passage are not discussed, and the reader is referred to notes 1, 2, and 6 for additional details6. Also details on the aerodynamic design methodology for the vane/blade passage are not presented.
Image | Turbine Blade Aerodynamics
| 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.
Search Contact: email@example.com