Multistage turbine expansion engines

1999 ◽  
Vol 35 (9) ◽  
pp. 516-520
Author(s):  
A. B. Davydov ◽  
A. N. Sherstyuk
Keyword(s):  
Turbine Expansion ◽  
Multistage Turbine

Simplified Analyses of Some Vapour Power Cycles

1996 ◽  
Vol 210 (3) ◽  
pp. 191-202 ◽  
Author(s):  
J H Horlock
Keyword(s):  
Thermal Efficiency ◽  
Low Pressure ◽  
Power Cycles ◽  
Turbine Expansion ◽  
The Difference

A range of vapour power cycles is analysed, using the assumption originally made by Schaff that along a turbine expansion line the difference between the (local) enthalpy (h) and the liquid enthalpy at the same pressure ( hL) may remain unchanged (β = h – hL is constant). The thermodynamics of the assumption are critically examined and it is found to be valid only over strictly limited ranges of properties (usually low-pressure levels). However, if such limitations are accepted, the analyses provide understanding of the effects of various key parameters on thermal efficiency, and of measures (such as feed heating, reheat, dual pressure boilers, etc.) that are taken to raise that efficiency.

Numerical simulation of multistage turbine sound generation and propagation

2005 ◽  
Vol 9 (2) ◽  
pp. 125-134 ◽  
Author(s):  
Detlef Korte ◽  
Thomas Hüttl ◽  
Fritz Kennepohl ◽  
Klaus Heinig
Keyword(s):  
Numerical Simulation ◽  
Sound Generation ◽  
Multistage Turbine

scholarly journals On Prediction of Off-Design Multistage Turbine Pressures by Stodola’s Ellipse

1984 ◽  
Author(s):  
David H. Cooke
Keyword(s):  
Linear Method ◽  
High Vacuum ◽  
Practical Experience ◽  
Flow Coefficient ◽  
Constant Flow ◽  
Theoretical Derivation ◽  
Derived Relations ◽  
Power Cycles ◽  
Multistage Turbine ◽  
The Law

The variation of extraction pressures with flow to the following stage for high backpressure, multistage turbine designs is highly non-linear in typical cogeneration applications where the turbine nozzles are not choked. Consequently, the linear method based on Constant Flow Coefficient, which is applicable for uncontrolled expansion with high vacuum exhaust as is common in utility power cycles, cannot be used to predict extraction pressures at off-design loads. The paper presents schematic examples and brief descriptions of cogeneration designs, with background and theoretical derivation of a more generalized “nozzle analogy” which is applicable in these cases. This method is known as the Law of the Ellipse. It was originally developed experimentally by Professor Stodola and published in English in 1927. The paper shows that the Constant Flow Coefficient method is really a special case of the more generalized Law of the Ellipse. Graphic interpretation of the Law of the Ellipse for controlled and uncontrolled expansions, and variations for sonic choking and reduced number of stages (including single stage) are presented. The derived relations are given in computer codable form, and methods of solution integral with overall heat balance iteration schemes are suggested, with successful practical experience. The pressures predicted by the relations compare favorably with manufacturers’ data on four high-backpressure, cogeneration cycle turbines and three large utility low-pressure ends.

Multistage Turbine Simulations With Vortex–Blade Interaction

1996 ◽  
Vol 118 (4) ◽  
pp. 643-653 ◽  
Author(s):  
M. G. Turner
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Test Data ◽  
Detrimental Effect ◽  
Vortex Interaction ◽  
Low Pressure Turbine ◽  
Blade Row ◽  
Multistage Turbine ◽  
Flow Vortex ◽  
Two Stages

The average passage approach of Adamczyk et al. (1990) has been used to simulate the multistage environment of the General Electric E3 low-pressure turbine. Four configurations have been analyzed and compared to test data. These include the nozzle only, the first stage, the first stage and a half, and the first two stages. A high casing slope on the first-stage nozzle causes the secondary flow vortex to separate off the casing and enter the downstream rotor. The detrimental effect on performance due to this vortex interaction has been predicted by the above approach, whereas isolated blade row calculations cannot simulate this interaction. The unsteady analysis developed by Chen et al. (1994) has also been run to understand the unsteady flow field in the first-stage rotor and compare with the average passage model and test data. Comparisons of both the steady and unsteady analyses with data are generally good, although in the region near the casing of the shrouded rotors, the predicted loss is lower than that shown by the data.

scholarly journals Uncertainty Quantification of Leakages in a Multistage Simulation and Comparison With Experiments

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
Cosimo Maria Mazzoni ◽  
Richard Ahlfeld ◽  
Budimir Rosic ◽  
Francesco Montomoli
Keyword(s):  
Uncertainty Quantification ◽  
Numerical Study ◽  
Turbine Blades ◽  
Industrial Practice ◽  
Turbine Efficiency ◽  
Simulation Based ◽  
Multistage Turbine ◽  
Computational Fluid Dynamics Cfd ◽  
Yaw Angle ◽  
The Impact

This paper presents a numerical study of the impact of tip gap uncertainties in a multistage turbine. It is well known that the rotor gap can change the gas turbine efficiency, but the impact of the random variation of the clearance height has not been investigated before. In this paper, the radial seals clearance of a datum shroud geometry, representative of steam turbine industrial practice, was systematically varied and numerically tested by means of unsteady computational fluid dynamics (CFD). By using a nonintrusive uncertainty quantification (UQ) simulation based on a sparse arbitrary moment-based approach, it is possible to predict the radial distribution of uncertainty in stagnation pressure and yaw angle at the exit of the turbine blades. This work shows that the impact of gap uncertainties propagates radially from the tip toward the hub of the turbine, and the complete span is affected by a variation of the rotor tip gap. This amplification of the uncertainty is mainly due to the low-aspect ratio of the turbine, and a similar behavior is expected in high pressure (HP) turbines.

scholarly journals Maximizing Multistage Turbine Efficiency by Optimizing Hub and Shroud Shapes and Inlet and Exit Conditions of Each Blade Row

1999 ◽  
Author(s):  
Milan V. Petrovic ◽  
George S. Dulikravich ◽  
Thomas J. Martin
Keyword(s):  
Search Algorithm ◽  
Flow Analysis ◽  
Axial Flow ◽  
Multidisciplinary Optimization ◽  
Design System ◽  
Optimized Design ◽  
Turbine Efficiency ◽  
Through Flow ◽  
Blade Row ◽  
Multistage Turbine

By matching a well established fast through-flow analysis code and an efficient optimization algorithm, a new design system has been developed which optimizes hub and shroud geometry and inlet and exit flow-field parameters for each blade row of a multistage axial flow turbine. The compressible steady state inviscid through-flow code with high fidelity loss and mixing models, based on stream function method and finite element solution procedure, is suitable for fast and accurate flow calculation and performance prediction of multistage axial flow turbines at design and significant off-design conditions. A general-purpose hybrid constrained optimization package has been developed that includes the following modules: genetic algorithm, simulated annealing, modified Nelder-Mead method, sequential quadratic programming, and Davidon-Fletcher-Powell gradient search algorithm. The optimizer performs automatic switching among the modules each time when the local minimum is detected thus offering a robust and versatile tool for constrained multidisciplinary optimization. An analysis of the loss correlations was made to find parameters that have influence on the turbine performance. By varying seventeen variables per each turbine stage it is possible to find an optimal radial distribution of flow parameters at the inlet and outlet of every blade row. Simultaneously, an optimized meridional flow path is found that is defined by the optimized shape of the hub and shroud. The design system has been demonstrated using an example of a single stage transonic axial gas turbine, although the method is directly applicable to multistage turbine optimization. The comparison of computed performance of initial and optimized design shows significant improvement in the turbine efficiency at design and off-design conditions. The entire design optimization process is feasible on a typical single-processor workstation.

Comparison of Numerical Methods for the Prediction of Time-Averaged Flow Quantities in a Cooled Multistage Turbine

2015 ◽  
Author(s):  
Ritu P. Marpu ◽  
Chad H. Custer ◽  
Venkataramanan Subramanian ◽  
Jonathan M. Weiss ◽  
Kenneth C. Hall
Keyword(s):  
Harmonic Balance ◽  
Fluid Dynamic ◽  
Unsteady Flows ◽  
Harmonic Balance Method ◽  
Pressure Profile ◽  
Balance Method ◽  
Pressure Profiles ◽  
Multistage Turbine ◽  
Temperature And Pressure ◽  
Flow Effects

An unsteady simulation of a two-stage, cooled, high pressure turbine cascade is achieved by applying the harmonic balance method, a mixed time domain and frequency domain computational fluid dynamic technique for efficiently solving periodic unsteady flows. A comparison of computed temperature and pressure profile predictions generated using the harmonic balance method and a conventional steady mixing plane analysis is presented. The predicted temperature and pressure profiles are also compared to experimental data at the stage exit plane. The harmonic balance solver is able to efficiently model unsteady flows caused by wake interaction and secondary flow effects due to cooling flows. It is demonstrated that modeling the unsteady effects is critical to the accurate prediction of time-averaged flow field quantities, particularly for cooled machines.

Simulation of Three-Dimensional Viscous Flow Within a Multistage Turbine

1990 ◽  
Vol 112 (3) ◽  
pp. 370-376 ◽  
Author(s):  
J. J. Adamczyk ◽  
M. L. Celestina ◽  
T. A. Beach ◽  
M. Barnett
Keyword(s):  
Aspect Ratio ◽  
Flow Field ◽  
Three Dimensional ◽  
Equation System ◽  
Aerodynamic Performance ◽  
Experimental Measurements ◽  
Low Aspect Ratio ◽  
Blade Row ◽  
Multistage Turbine ◽  
Secondary Flow Field

This work outlines a procedure for simulating the flow field within multistage turbomachinery, which includes the effects of unsteadiness, compressibility, and viscosity. The associated modeling equations are the average passage equation system, which governs the time-averaged flow field within a typical passage of a blade row embedded within a multistage configuration. The results from a simulation of a low aspect ratio stage and one-half turbine will be presented and compared with experimental measurements. It will be shown that the secondary flow field generated by the rotor causes the aerodynamic performance of the downstream vane to be significantly different from that of an isolated blade row.

Aerodynamic optimisation of a low-pressure multistage turbine using the response-surface method

2013 ◽  
Vol 27 (8) ◽  
pp. 2537-2546 ◽  
Author(s):  
Yu Li ◽  
Liang Li ◽  
Tong Zhao ◽  
Jun Li
Keyword(s):  
Response Surface ◽  
Response Surface Method ◽  
Low Pressure ◽  
Surface Method ◽  
Multistage Turbine

Unsteady Aerodynamical Blade Row Interaction in a New Multistage Research Turbine: Part 2 — Numerical Investigation

2001 ◽  
Author(s):  
Wolfgang Höhn ◽  
Ralf Gombert ◽  
Astrid Kraus
Keyword(s):  
Boundary Layer ◽  
Grid Method ◽  
Low Pressure ◽  
Equation Model ◽  
Navier Stokes ◽  
Viscous Boundary Layer ◽  
Low Pressure Turbine ◽  
Blade Row ◽  
Multistage Turbine ◽  
Blade Row Interaction

This paper is the second part of a two part paper, which describes in part one the experimental setup and results of a new multistage turbine. Part two presents results of unsteady viscous flow calculations based on cold flow experiments of that three stage low pressure turbine. The present paper emphasizes the investigation of stator-stator interaction of a low pressure turbine section of a commercial jet engine. Different positions for the second and third stator are studied numerically and experimentally with respect to the blade row interaction, unsteady blade loading and unsteady boundary layer effects. A time accurate Reynolds averaged Navier-Stokes solver is applied for the computations. Turbulence is modeled using the Spalart-Allmaras one equation model turbulence model and the influence of modern transition models on the unsteady flow predictions is investigated. The integration of the governing equations in time is performed by a four stage Runge-Kutta scheme, which is accelerated by a two grid method in the viscous boundary layer around the blades and alternatively by a dual time stepping method. At the inlet and outlet reflecting or non-reflecting boundary conditions are used. The quasi 3D calculations are conducted on a stream surface around midspan allowing a varying stream tube thickness. In particular, the flow field with respect to time averaged and unsteady quantities such as surface pressure, vorticity, unsteady velocity field and skin friction are compared with the experiments conducted in the cold air flow test rig.

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