Piotr Lampart

Design analysis of Tesla micro-turbine operating on a low-boiling medium

Design analysis of Tesla micro-turbine operating on a low-boiling medium This paper presents results of the design analysis of a Tesla bladeless turbine intended for a co-generating micro-power plant of heat capacity 20 kW, which operates in an organic Rankine cycle on a low-boiling medium. Numerical calculations of flow in several Tesla turbine models were performed for a range of design parameters. Results of investigations exhibit interesting features in the distribution of flow parameters within the turbine interdisk space. The calculated flow efficiency of the investigated Tesla turbine models show that the best obtained solutions can be competitive as compared with classical small bladed turbines.

Unsteady Load of Partial Admission Control Stage Rotor of a Large Power Steam Turbine

Partial admission flow in the control stage of a 200MW steam turbine is investigated with the help of a RANS solver with k-ω SST turbulence model in the code Fluent. A 2D model of flow at the mid-span section of the full annulus is assumed. The results exhibit interesting details of the process of expansion in the control stage. Unsteady forces acting on the single rotor blades of the control stage are calculated, and are subject to Fourier analysis. Single blade forces are summed up to obtain the unsteady load at the rotor (forces acting at the rotor disc are neglected due to the assumed 2D model). The calculations take into account pressure pulsations at the entry to the nozzle boxes and rotor blade mistuning / geometrical imperfections.Copyright

Tip Leakage/Main Flow Interactions in Multi-Stage HP Turbines With Short-Height Blading

Interaction of the main flow with tip leakage over shrouded rotor blades in a multi-stage turbine is studied numerically. The flow in blade-to-blade channels is computed with the aid of a 3D Navier-Stokes solver FlowER with the Menter SST turbulence model. In this paper, the labyrinth seals are not computed but the numerical scheme is modified to include the source/sink-type boundary conditions at places at the endwalls referring to design locations of injection of leakage flows into, or their extraction from, the blade-to-blade passage. Without considering complete labyrinth seal geometries, the tip leakage jet is represented by its flow rate and direction at re-entry to the blade-to-blade passage, as if referring to the performance of a range of different labyrinth seal arrangements. The effect of direction of tip leakage re-entry on the downstream flow and efficiency of the turbine stage (stage group) is studied. The calculation method is validated on a model air stator/rotor turbine.© 2004 ASME

Increasing flow efficiency of high-pressure and low-pressure steam turbine stages from numerical optimization of 3D blading

3D blading of a high-pressure and low-pressure steam turbine stage is optimized using Nelder–Mead method of deformed polyhedron. Values of the minimized objective function, i.e. stage losses with the exit energy are found from 3D viscous compressible flow computations, including turbulence effects. Among the optimized parameters are stator and rotor blade numbers and stagger angles, rotor blade twist angle, stator blade sweep and lean, both straight and compound. The blade sections (profiles) are assumed not to change during the optimization. There are constraints imposed on the design parameters, including the mass flow rate and stage reaction. Optimization gives designs with new 3D blade stacking lines, and with increased efficiencies, compared with the original design.

Validation of a 3D RANS Solver With a State Equation of Thermally Perfect and Calorically Imperfect Gas on a Multi-Stage Low-Pressure Steam Turbine Flow

A state equation of thermally perfect and calorically imperfect gas is implemented in a 3D RANS solver for turbomachinery flow applications. The specific heats are assumed as linear functions of temperature. The model is validated on a five-stage low-pressure steam turbine. The computational results exhibit the process of expansion in the turbine

On the Importance of Adaptive Control in Extraction/Condensing Turbines

Adaptive control in low-pressure (LP) steam turbines is applicable to the conditions of steam extraction, leading to significant gains in flow efficiency and turbine power. This paper summarizes the importance of adaptive control, making a set of computations based on the model of adaptive stage with adjustable nozzle blades that can adapt the geometry of the blading system to the changing flow conditions. An increase of turbine efficiency and power coming from adaptive control is estimated for a group of two exit stages of an extraction/condensing turbine of power 60 MW. The calculations are made with the help of a computer code FlowER — a 3D solver of turbomachinery flows based on Reynolds-averaged Navier-Stokes (RANS) equations for perfect gas.Copyright

Numerical Optimisation of a High Pressure steam Turbine Stage

Blading of a high-pressure (HP) steam turbine stage is optimised using an idea of direct constraint optimisation. The objective function to be minimised is the enthalpy loss of the stage. A simplex method of deformed polyhedron proposed by Nelder-Mead is used for optimisation. Current values of the objective function are found from 3D Reynolds-Averaged Navier Stokes (RANS) computations. To secure global flow conditions, there are constraints imposed on the mass flow rate, exit swirl angle, and reaction. The optimised parameters are here the stator and rotor blade numbers and stagger angles, rotor blade twist angle and parameters of stator blade compound lean at root and tip. Blade profiles are not changed. Optimisation gives a design with new 3D stacking lines of the blades and increased flow efficiency, compared to the original design.

Numerical Optimization of Stator Blade Sweep and Lean in an LP Turbine Stage

The paper describes results of direct constrained optimization of stator blade axial sweep and circumferential lean for the exit stage of a large power steam turbine, using Nelder-Mead’s method of deformed polyhedron. Values of the minimised objective function, that is stage losses with the exit energy are found from 3D viscous compressible computations. Turbulence effects are taken into account using Menter’s SST model. Among the optimized parameters are stator and rotor stagger angles, stator straight sweep and straight lean, stator compound sweep at the tip and compound lean at the root, giving the total number of 8 optimized parameters. The blade sections (profiles) are assumed not to change during the optimization. There are constraints imposed on the mass flow rate, exit swirl angle and reactions. A number of optimization runs is reported. First, optimization of the exit stage with stator blade circumferential lean, second, optimization of the stage with stator blade axial sweep, then, the stage is optimized with both sweep and lean of stator blades. In the above tasks, the process of optimization is carried out for a nominal load, however, due to the fact that exit stages of steam turbines operate over a wide range of flow rates away from the nominal conditions, the original and final geometries are also checked for low and high loads. Optimization gives designs with new 3D stacking lines of stator blades, and with significantly increased efficiencies, over large part of the assumed range of load, compared to the original design.Copyright

Design and numerical study of turbines operating with MDM asworking fluid

Abstract Design processes and numerical simulations have been presented for a few cases of turbines designated to work in ORC systems. The chosen working fluid isMDM. The considered design configurations include single stage centripetal reaction and centrifugal impulse turbines as well as multistage axial turbines. The power outputs vary from about 75 kW to 1 MW. The flow in single stage turbines is supersonic and requires special design of blades. The internal efficiencies of these configurations exceed 80% which is considered high for these type of machines. The efficiency of axial turbines exceed 90%. Possible turbine optimization directions have been also outlined in the work.

CFD analysis of fluid flow in an axial multi-stage partial-admission ORC turbine

Abstract Basic operational advantages of the Organic Rankine Cycle (ORC) systems and specific issues of turbines working in these systems are discussed. The strategy for CFD simulation of the considered ORC turbine and the main issues of the numerical model are presented. The method of constructing the 3D CAD geometry as well as discretisation of the flow domain are also shown. Main features of partial admission flow in the multi-stage axial turbine are discussed. The influence of partial admission on the working conditions of the subsequent stage supplied at the full circumference is also described.