scholarly journals Axial Turbine Performance Estimation During Dynamic Operations

2020 ◽  
Author(s):  
Razvan Nicoara ◽  
Valeriu Vilag ◽  
Jeni Vilag ◽  
Zoltan Kolozvary
Keyword(s):  
Performance Estimation ◽  
Axial Turbine ◽  
Turbine Performance

Scaling of Gas Turbine From Air to Refrigerants for Organic Rankine Cycle Using Similarity Concept

2015 ◽  
Vol 138 (6) ◽  
Author(s):  
Choon Seng Wong ◽  
Susan Krumdieck
Keyword(s):  
Gas Turbine ◽  
Test Bench ◽  
Pressure Ratio ◽  
Organic Rankine Cycle ◽  
Rankine Cycle ◽  
Expansion Ratio ◽  
Performance Estimation ◽  
Working Fluids ◽  
Turbine Performance ◽  
Performance Map

Similitude, or similarity concept, is an essential concept in turbomachinery to allow the designer to scale a turbine design to different sizes or different working fluids without repeating the whole design and development process. Similarity concept allows the testing of a turbomachine in a simple air test bench instead of a full-scale organic Rankine cycle (ORC) test bench. The concept can be further applied to adapt an existing gas turbine as an ORC turbine using different working fluids. This paper aims to scale an industrial gas turbine to different working fluids, other than the fluid the turbine was originally designed for. The turbine performance map for air was generated using the 3D computational fluid dynamics (CFD) analysis tools. Three different approaches using the similarity concept were applied to scale the turbine performance map using air and generate the performance map for two refrigerants: R134a and R245fa. The scaled performance curves derived from the air performance data were compared to the performance map generated using CFD analysis tools for R134a and R245fa. The three approaches were compared in terms of the accuracy of the performance estimation, and the most feasible approach was selected. The result shows that complete similarity cannot be achieved for the same turbomachine with two different working fluids, even at the best efficiency point for particular expansion ratio. If the constant pressure ratio is imposed, the location of the optimal velocity ratio and optimal specific speed would be underestimated with calculation error over 20%. Constant Δh0s/a012 was found to provide the highest accuracy in the performance estimation, but the expansion ratio (or pressure ratio) is varying using different working fluids due to the variation of sound speed. The differences in the fluid properties and the expansion ratio lead to the deviation in turbine performance parameters, velocity diagram, turbine's exit swirl angle, and entropy generation. The use of Δh0s/a012 further limits the application of the gas turbine for refrigerants with heavier molecular weight to a pressure ratio less than the designed pressure ratio using air. The specific speed at the best efficiency point was shifted to a higher value if higher expansion ratio was imposed. A correction chart for R245fa was attempted to estimate the turbine's performance at higher expansion ratio as a function of volumetric flow ratio.

Quantitative Risk Assessment for the Performance Estimation of a Gas Turbine Upgrade

2010 ◽  
Author(s):  
Sebastian Heinze ◽  
Kerstin Tageman ◽  
A˚ke Klang ◽  
Anna Molker
Keyword(s):  
Risk Assessment ◽  
Gas Turbine ◽  
Probability Distributions ◽  
Air Flow ◽  
Performance Estimation ◽  
Upper And Lower Bounds ◽  
Turbine Performance ◽  
Experimental Plan ◽  
Swallowing Capacity ◽  
Cooling Air

This paper presents a study that has been conducted within a gas turbine development project aiming at an upgrade of an existing twin-shaft gas turbine. There are a number of uncertainties, both in the original turbine as well as in the introduced modifications. These uncertainties must be taken into consideration when setting performance guarantee margins for the turbine. In order to quantify the impact of those uncertainties on the turbine performance, a probabilistic risk assessment was performed. Uncertain parameters for the compressor turbine were defined and upper and lower bounds as well as probability distributions were estimated. The MINITAB software was used to determine an experimental plan resulting in test points that were investigated with aerodynamic and secondary air flow tools. Based on results from this analysis, a second-order metamodel was determined. The metamodel was fed with 20000 random parameter combinations according to the parameter probability distributions, and efficiency, swallowing capacity and cooling air flow probability distributions were calculated. In a second step, the resulting values were used as uncertain input parameters to the gas turbine performance analysis considering the entire gas turbine including compressor and combustor. An experimental plan was determined based on calculated bounds for the compressor turbine efficiency, swallowing capacity and cooling air flows. A metamodel was calculated, and again 20000 parameter combinations were randomly generated based on the found parameter distributions. The parameters were fed to the metamodel of the entire gas turbine, and probability distributions for the gas turbine overall power and efficiency were found. Results from the investigations were used to set guarantee margins for power and efficiency.

Experimental Comparison of Axial Turbine Performance Under Steady and Pulsating Flows

2014 ◽  
Vol 136 (11) ◽  
Author(s):  
A. St. George ◽  
R. Driscoll ◽  
E. Gutmark ◽  
D. Munday
Keyword(s):  
Incidence Angle ◽  
Experimental Comparison ◽  
Strong Function ◽  
Axial Turbine ◽  
Turbine Efficiency ◽  
Turbine Performance ◽  
Pulsed Detonation ◽  
Pulsed Flow ◽  
Partial Admission ◽  
Corrected Flow

The performance of an axial turbine is studied under close-coupled, out-of-phase, multiple-admission pulsed air flow to approximate turbine behavior under pulsed detonation inflow. The operating range has been mapped for four frequencies and compared using multiple averaging approaches and five formulations of efficiency. Steady performance data for full and partial admission are presented as a basis for comparison to the pulsed flow cases. While time-averaged methods are found to be unsuitable, mass-averaged, work-averaged, and integrated instantaneous methods yield physically meaningful values and comparable trends for all frequencies. Peak work-averaged efficiency for pulsed flow cases is within 5% of the peak steady, full admission values for all frequencies, in contrast to the roughly 15–20% performance deficit experienced under steady, 50% partial admission conditions. Turbine efficiency is found to be a strong function of corrected flow rate and mass-averaged rotor incidence angle, but only weakly dependent on frequency.

Experimental Comparison of Axial Turbine Performance Under Steady and Pulsating Flows

2014 ◽  
Author(s):  
A. St. George ◽  
R. Driscoll ◽  
E. Gutmark ◽  
D. Munday
Keyword(s):  
Incidence Angle ◽  
Experimental Comparison ◽  
Strong Function ◽  
Axial Turbine ◽  
Turbine Efficiency ◽  
Turbine Performance ◽  
Pulsed Detonation ◽  
Pulsed Flow ◽  
Partial Admission ◽  
Corrected Flow

The performance of an axial turbine is studied under close-coupled, out-of-phase, multiple-admission pulsed air flow to approximate turbine behavior under pulsed detonation inflow. The operating range has been mapped for four frequencies and compared using multiple averaging approaches and five formulations of efficiency. Steady performance data for full and partial admission are presented as a basis for comparison to the pulsed flow cases. While time-averaged methods are found to be unsuitable, mass-averaged, work-averaged, and integrated instantaneous methods yield physically meaningful values and comparable trends for all frequencies. Peak work-averaged efficiency for pulsed flow cases is within 5% of the peak steady, full admission values for all frequencies, in contrast to the roughly 15–20% performance deficit experienced under steady, 50% partial admission conditions. Turbine efficiency is found to be a strong function of corrected flow rate and mass-averaged rotor incidence angle, but only weakly dependent on frequency.

A Propeller Model for Steady-State and Transient Performance Prediction of Turboprop and Counter-Rotating Open Rotor Engines

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Vinícius Tavares Silva ◽  
Cleverson Bringhenti ◽  
Jesuino Takachi Tomita ◽  
Anderson Frasson Fontes
Keyword(s):  
Steady State ◽  
Gas Turbine ◽  
Performance Prediction ◽  
Pitch Angle ◽  
Operating Conditions ◽  
Performance Estimation ◽  
Transient Performance ◽  
Turbine Performance ◽  
Constant Pitch ◽  
Open Rotor

This paper describes a methodology used for propeller performance estimation, which was implemented in an in-house modular program for gas turbine performance prediction. A model based on subsonic generic propeller maps and corrected for compressibility effects, under high subsonic speeds, was proposed and implemented. Considering this methodology, it is possible to simulate conventional turboprop architectures and counter-rotating open rotor (CROR) engines in both steady-state and transient operating conditions. Two simulation scenarios are available: variable pitch angle propeller with constant speed; or variable speed propeller with constant pitch angle. The simulations results were compared with test bench data and two gas turbine performance commercial software packages were used to fulfill the model validation for conventional turboprop configurations. Furthermore, a direct drive CROR engine was simulated using a variable inlet guide vanes (VIGV) control strategy during transient operation. The model has shown to be able to provide several information about propeller-based engine performance using few input data, and a comprehensive understanding on steady-state and transient performance behavior was achieved in the obtained results.

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