Radial Flow Turbine Research Articles

Analytical Optimization Design of Radial and Mixed Flow Turbines

The optimization of radial and mixed flow turbine design, based on simple one-dimensional aerodynamic principles, is described. The objective is to minimize energy losses by reducing the inlet and exit velocities of the rotor. The procedure is based on the specification of a loading coefficient. Previous work has shown that turbines of this type have loading coefficients that lie in a narrow band, and so suitable values can be readily determined. A more detailed specification of losses is unnecessary for the optimization. Optimizations are described for zero and non-zero inlet blade angles, and zero, positive and negative exit swirl conditions.

The Design and Testing of a Radial Flow Turbine for Aerodynamic Research

This paper describes the design of a high-speed radial inflow turbine for use as part of a gas generator, and the design of a large-scale (1.2 m tip diameter) low-speed model of the high-speed turbine. Streamline curvature throughflow, two-dimensional blade-to-blade, and fully three-dimensional inviscid and viscous calculation methods have been used extensively in the analysis of the designs. The use of appropriate scaling parameters and their impact on turbine performance is discussed. A simple model shows, for example, how to model the blade lean in the inducer, which serves to balance the effect of meridional curvature at inlet to the rotor and can be used to unload the rotor tip. A brief description of the low-speed experimental facility is followed by a presentation and discussion of experimental results. These include surface flow visualization patterns on both the rotor and stator blades and blade row exit traverses.

Principles of Turbomachinery

List of symbols used, their meaning and dimensions. Fundamental principles. Principles and practice of scaling laws. Principles of axial flow machines. Principles of radial and mixed flow machines. Centrifugal machines. Axial machines for incompressible flow. Axial turbines and compressors for compressible flow. Radial flow turbines. Cavitation and other matters.

Design specifications and application of a100 kW c(700 kW th) cogeneration solar power plant

A 100 kW e/700 kW th distributed receiver, solar-thermal power plant was installed in remote desertlocation 35 km southwest of Kuwait City in the country of Kuwait. The co-generation solar power plant is designed to supply the electric power and fresh water, needs of a small agricultural desert settlement. The power plane utilizes 56 point-focusing, parabolic collectors, each five meters in diameter and equipped with a two-axis tracking system. A synthetic fluid is circulated in the collector field via a pipeline network, where it is heated to 400°C. In the energy conversion system, the heat-transfer fluid enters a series of heat exchangers where it heats and vaporizes another organic fluid (Toluene). The vapor, under high pressure, operates a radial flow turbine, producing mechanical and, subsequently, electric energy. The rejected heat is ultimately to be used for powering of a multistage flash desalination system to provide the fresh water needs for the integrated food-water-power complex which also includes desert greehouses and outdoor irrigation system.

Ammonia Turbine Design for Ocean Thermal Energy Conversion (OTEC) Plants

During the optimization studies of a 10-MWe (net) OTEC power system the ammonia turbine design study led to selection of a four-stage, double-flow axial turbine yielding 89.6 percent efficiency at 1800 rpm. To maximize power at off-nominal conditions, variable nozzles are used for the first stage. The turbine is directly connected to a four-pole, 60-Hz synchronous generator having 97.2 percent efficiency. This study was limited to state-of-the-art hardware designs for axial- and radial-flow turbines, single- and double-flow designs, and variations in the base diameter and number of turbine stages. The gasdynamic calculation procedure and the effects of the turbine generator control scheme, turbine blade design, materials (annealed AISI Type 403 steel is chosen for the blading), and seals and bearings are addressed in this paper. The estimated mass-production cost of the turbine-generator set is approximately $150/kWe at 10-MWe (net) size in 1979 dollars. Single-flow-axial and radial-inflow turbines would have lower performance without sufficiently lower cost to be cost-effective, since each percentage point of turbine efficiency is estimated to be worth 17 to $28/kWe.

Application of All-Ceramic Nozzle to Radial Flow Turbine

An all-ceramic turbine nozzle offers the capability for improved erosion resistance and up-rated turbine inlet temperature. This yields significant improvement in engine durability and performance. Results of ceramic turbine nozzle engine tests and engine simulator tests for a small radial flow gas turbine are presented. The effects of erosive particles and ingested sea salt on the ceramics are included in this work.

高炉炉頂圧発電の現状について

Recently, top gas pressure recovery turbine plants have been installed in some steel making plants for energy saving. Eleven turbine plants have been operated including two test plants in Japan.Total operation time of the first plant (Kawasaki Steel Corp. Mizushima Works No. 2 B.F) was approximately 26 400 hours.There are two basic types of turbines for energy recovery; wet and dry. A radial flow turbine is of the wet type, and an axial flow turbine is of the dry type. Each turbine has special devices designed for prevention of corrosion, erosion and clogging of the turbine by dust and moisture-laden gas. These turbine systems have had no effect in any way on the blast furnace operation. Recovery turbine output of the first plant reaches 20 to 30% of blast blower input energy and its availability, approximately 85%, is over the average of self-thermal power plants in steel making plants.In the future, economical plants will be developed for further improvement of turbine output and higher reliability of turbine systems including gas cleaning equipment.

Performance of Radial Flow Turbines Under Pulsating Flow Conditions

Investigations of the pulsating flow performances of an inward radial flow turbine were performed. The quasi-steady flow performances predicted from the measured transient pressure ratio and from steady flow performance data were compared with the measured mean performances under pulsating flow conditions over the pulse frequency range of 30 Hz–70 Hz. The validity of this quasi-steady flow assumption was treated more generally than by the hitherto employed method by adopting a new empirical parameter which indicates both the pressure pulse shape and the amplitude of pressure fluctuation, in addition to the pulse frequency.

Closure to “Discussions of ‘Performance of Radial Flow Turbines Under Pulsating Flow Conditions’” (1976, ASME J. Eng. Power, 98, p. 59)

Closure to “Discussions of ‘Performance of Radial Flow Turbines Under Pulsating Flow Conditions’” (1976, ASME J. Eng. Power, 98, p. 59)

Attrition mill operating characteristics

The attrition mill is a device for mechanically reducing solid particle size by intense agitation of a slurry of material being milled and coarse milling media. For example, in 10 hours of milling, specific surfaces of 40 and 25 m 2/g were obtained for alumina and barite, corresponding to 38 and 56 nm equivalent spherical diameter, respectively. Size reduction rates for relatively coarse particles were first-order and increased linearly with power input to the mill. Optimum milling medium concentration corresponded to medium particles moving a distance of approximately 0.7 of their diameter before collision with another such particle. Power characteristics of the attrition mill were essentially the same as those of a radial flow turbine mixer. Laminar flow became disrupted at N Re ≈ 200, while turbulent flow was established at N Re > 8000. Slurries of fine powders exhibited the same linear power-average density dependence as single-phase liquids. However, a different dependence was observed with large particles.

Turbocharging of Small Engines

During the last 20 years, progressively smaller diesel engines have been turbocharged, so that units of 50-60 hp are produced today. Spark-ignition engines remain normally aspirated for most applications, although this picture may change. Progress followed the adoption of radial flow turbines using lost-wax cast rotors. Other developments included:raising component efficiencies; dealing with bearing and seal design problems, and with vane vibration; and in devising manufacturing methods for quantities approaching 3000 weekly, in mixed and rapidly changing batch sizes. Various control systems are available to match the turbocharger to the demands of variable speed engines.

Performance of Inward Radial Flow Turbines under Unsteady Flow Conditions with Full and Partial Admission

The paper describes the most recent work to be completed in the unsteady flow investigation on radial flow turbines, earlier unsteady flow work for single entry casings having been reported in (1)†and (2), and steady flow work for very high pressure ratios and multiple admission in (3). The present paper combines these analyses to give a coherent treatment of single and multiple admission.

Bearing capacity of semi-open radial-flow turbine wheels

1. The hypotheses relating to the interaction of the discrete blades and disc of semi-open wheels, with plastic deformation and failure, have been confirmed experimentally. Reducing the pitch of the blading tends to localize plastic deformations and premature failure of the wheel in the event of inadequate deformation capacity of the material. 2. The determining role of radial stresses in the disc has been established in the event of failure of solid turbine wheels and of compressor wheels with a central orifice when made from materials with a limited deformation capacity (1/m>0.3), and relative number of blades\(\bar z \geqslant 0.7\). 3. The problem has been resolved relating to determination of maximum radial stresses and speeds, considering the interference effect of the blading and the actual properties of the metal and design of the wheel. 4. Design criteria have been established for the strength of wheels to centrifugal forces.

The Dynamic Characteristics and Control of a Hydraulic Turbine

A dynamic model of a radial flow turbine was derived. The model was verified by tests on an experimental 5 hp Francis type turbine. The tests indicate that the model is adequate for control system design. A simulation of the model was used to study possible forms of turbine control. The studies demonstrated the advantages of simple adaptive and feedforward control.

Paper 9: Theoretical and Experimental Studies of Wet Steam Erosion in a Counter-Rotating Radial Steam Turbine

Erosion test in a model counter-rotating radial flow turbine has been performed to assist in the design of a 460-MW radial flow turbine. Three rows of erosion specimens were inserted at different radial locations in the last blade ring upstream of the blades to investigate the influence of the radial distance between the stages. Results showed that small droplets were formed and that erosion diminished with increased radial spacing up to a certain distance. A theoretical model for calculating droplet trajectories, sizes, and impact velocities has been derived, taking full account of wake velocity, variable droplet drag coefficient, and atomization. The calculations explained all the experimental facts and made it possible to convert the model test results to the full-size turbine showing no risk of erosion in the latter.

Performance of Inward Radial Flow Turbines under Non-Steady Flow Conditions

The paper describes theoretical and experimental work on pulse operation of inward radial flow turbines, together with certain essential steady flow data. Power measurement was by means of a specially developed high speed dynamometer, capable of speeds up to 10 000 rev/min, which is described in some detail. Steady flow tests confirmed the expected trends of mass flow and torque as functions of turbine speed and overall pressure ratio, and in addition proved the reliability, consistency and accuracy of the dynamometer. The unsteady flow analysis of Appendix 1 which is unique in incorporating a very full description of rotor geometry as well as of the complex nozzle-rotor interspace conditions, was applied to two particular experimental cases and gives good agreement with respect to pressure variation in the pipe system, turbine volute and at nozzle exit, but rather less satisfactory agreement with respect to power. Further theoretical work is summarized at the end of the paper.

Performance of Inward Radial Flow Turbines under Steady Flow Conditions with Special Reference to High Pressure Ratios and Partial Admission

The paper describes an extension of an earlier and very successful one-dimensional analysis by one of the authors (reference (1)) for design and off-design performance evaluation of inward radial flow turbines to include four cases not covered by the earlier analysis: high overall pressure ratios leading to either nozzle or rotor choking; partial admission; variable nozzle angle; allowance for nozzle and rotor loss coefficients (references (2) and (3)). Each of these extensions of the original theory has been programmed in FORTRAN. The full admission results are compared with performance measurements obtained on a C.A.V. type 01 turbine in conjunction with a specially designed high-speed dynamometer for pressure ratios up to 1.6, the analysis being extended to a maximum value of 4.0. The partial admission results are compared with experimental results reported in reference (4). The variable nozzle angle results are given as an example of the flexibility of the method. Finally, the loss coefficient treatment of Benson (reference (2)) which was based on reference (1) in conjunction with experimental results reported in reference (5), is applied to the full admission tests of the present paper. The object of the paper is to give a comprehensive account of the power of the one-dimensional treatment as a design tool, with the inference that two-and three-dimensional treatments (references (6)-(9)) are basically more suitable for detailed flow analysis rather than basic design.

Paper 42: A Simple Theory for the Prediction of Losses in the Rotors of Inward Radial Flow Turbines

The results of tests on a series of small inward radial flow turbines, reported by Hiett and Johnston, are analysed. Stagnation type pressure loss coefficients are established for the rotors, enabling their performance to be predicted with fair accuracy over a wide range of operating conditions in both directions of rotation. In particular, secondary losses are related to the forces acting on the vanes, using a similar method to that of Ainley and Mathieson for axial flow turbines. Additional losses occurring during reverse rotation are related to the variation of lift coefficient with radius in the exducer.

Paper 1: Theoretical Assessment of the Non-Steady Flow Performance of Inward Radial Flow Turbines

Paper 1: Theoretical Assessment of the Non-Steady Flow Performance of Inward Radial Flow Turbines

Paper 23: An Investigation of the Losses in the Rotor of a Radial Flow Gas Turbine at Zero Incidence under Conditions of Steady Flow

The performance of a radial flow turbine, operating on compressed air, is measured over a range of pressure ratio and speed. Separate tests on the nozzle assembly alone enable the rotor performance to be separated from the overall characteristics. In particular, the conditions at each pressure ratio for which the nozzle exit whirl velocity is equal to the rotor tip speed may be deduced. Also, it is possible to evaluate the enthalpy ‘loss’ in the rotor, that is, the difference between the specific enthalpy drop actually occurring in the rotor and its isentropic value. An attempt is then made to relate this loss with the relative velocities within the rotor passages as predicted by inviscid, two-dimensional analytical techniques. The method developed by Stanitz and co-workers has been programmed to analyse the rotor internal fluid flow properties in the blade-to-blade plane for the conditions of zero incidence. The region investigated does not include the whole rotor, but extends from a boundary upstream of the blade tip to a downstream boundary at a radius equal to 72 per cent of the tip radius. The analysis is performed for overall turbine static to static pressure ratios of 1·2 to 1·6. The result of the theoretical analysis is to show that the variable ratio of rotor outlet to inlet specific volume with changing pressure ratio is accommodated almost entirely without any change in the flow distribution; that is, over the region of the impeller investigated, and at overall turbine pressure ratios up to 1·6, the compressible flow through the rotor may be considered as being through stream tubes of fixed geometry. There is thus a sound basis for the correlation of rotor loss coefficient in terms of parameters which describe compressible flow with friction along variable area pipes. Consideration is given to the manner in which the zero incidence loss coefficient may be defined in order to remain constant at varying pressure ratios.