scholarly journals Off-Design Flow Analysis and Performance Prediction of Axial Turbines

1997 ◽  
Author(s):  
Milan V. Petrovic ◽  
Walter Riess
Keyword(s):  
Performance Prediction ◽  
Operating Conditions ◽  
Flow Reversal ◽  
Design Flow ◽  
Experimental Investigations ◽  
Local Flow ◽  
Through Flow ◽  
Wide Range ◽  
And Performance ◽  
Axial Turbines

Through-flow methods for calculations in axial flow turbines are limited by two facts: they cannot handle local flow reversal, and loss prediction at off-design operating conditions is not sufficiently accurate. An attempt to overcome these limitations is presented in this paper. The developed calculation method is based on the through-flow theory and the finite element solution procedure, but it also includes extensions and improvements. Consequently, the method may be used to predict the flow field and the turbine performance at the design load as well as for wide range of part loads. The code is able to calculate flow in axial turbines at subsonic and transonic conditions. The reliability of the method is verified by calculations for several gas and steam turbines. Results of flow calculation and performance prediction of 4-stage experimental air turbine and LP steam turbine are also presented herein. Low load operation with flow reversal in the hub region behind the last rotor blade row and loads, at which part of blading operates with power consumption, are especially analyzed. All numerical results are compared to the results of extensive experimental investigations. The correspondence, even for low loads, is very good.

scholarly journals Current Advances in Ejector Modeling, Experimentation and Applications for Refrigeration and Heat Pumps. Part 2: Two-Phase Ejectors

Inventions ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 16 ◽  
Author(s):  
Zine Aidoun ◽  
Khaled Ameur ◽  
Mehdi Falsafioon ◽  
Messaoud Badache
Keyword(s):  
Heat Pumps ◽  
Operating Conditions ◽  
Industrial Processes ◽  
Experimental Investigations ◽  
Mixing Enhancement ◽  
Data Generation ◽  
Two Phase ◽  
Wide Range ◽  
Potential Applications ◽  
And Performance

Two-phase ejectors play a major role as refrigerant expansion devices in vapor compression systems and can find potential applications in many other industrial processes. As a result, they have become a focus of attention for the last few decades from the scientific community, not only for the expansion work recovery in a wide range of refrigeration and heat pump cycles but also in industrial processes as entrainment and mixing enhancement agents. This review provides relevant findings and trends, characterizing the design, operation and performance of the two-phase ejector as a component. Effects of geometry, operating conditions and the main developments in terms of theoretical and experimental approaches, rating methods and applications are discussed in detail. Ejector expansion refrigeration cycles (EERC) as well as the related theoretical and experimental research are reported. New and other relevant cycle combinations proposed in the recent literature are organized under theoretical and experimental headings by refrigerant types and/or by chronology whenever appropriate and systematically commented. This review brings out the fact that theoretical ejector and cycle studies outnumber experimental investigations and data generation. More emerging numerical studies of two-phase ejectors are a positive step, which has to be further supported by more validation work.

An Automatic Car Heater System-Description and Performance Prediction

1968 ◽  
Vol 183 (1) ◽  
pp. 125-135
Author(s):  
A. G. Plackett
Keyword(s):  
Performance Prediction ◽  
Digital Computer ◽  
System Parameter ◽  
Operating Conditions ◽  
Comfort Level ◽  
System Description ◽  
Wide Range ◽  
System Components ◽  
Overall Performance ◽  
And Performance

The objective of the system is to control the car heater temperature to ensure an optimum comfort level, without the need for periodic adjustment, despite variations in ambient temperature and vehicle usage. Reasons for choosing a particular type of system are explained. The operation is analysed, and expressed in terms of an equation. Difficulties in solution due to non-linear terms are overcome with the aid of a digital computer. Test data on the system components and vehicle characteristics are used in the computer program to obtain a prediction of the accuracy of temperature control over a wide range of operating conditions. Predicted performance is compared with actual road tests results for an installation. Design optimization is facilitated by using the computer to examine the effect of system parameter changes on the overall performance.

Development and Validation of a New Universal Through Flow Method for Axial Compressors

2009 ◽  
Author(s):  
Milan V. Petrovic ◽  
Alexander Wiedermann ◽  
Milan B. Banjac
Keyword(s):  
Flow Analysis ◽  
Solution Procedure ◽  
Operating Conditions ◽  
Distribution Model ◽  
Test Cases ◽  
Flow Method ◽  
Through Flow ◽  
Wide Range ◽  
Flow Effects ◽  
And Performance

This paper describes the development of a new through flow method for the analysis of axial multistage compressors. The method is based on a stream function approach and a finite element solution procedure. It includes a high-fidelity loss and deviation model with improved correlations and endwall boundary layer calculation. A radial distribution model of losses and a new spanwise mixing model are applied to simulate 3D flow effects. The calibration of the models is made by calculation a number of test cases with different configurations with the aim of achieving high accuracy and optimum robustness for each of the test cases considered. The code was applied to flow analysis and performance prediction of a newly developed gas turbine compressor. Comparison of the predicted results and measured test data for the overall compressor performance and a number of parameters under different operating conditions showed good agreement. The results of the validation confirm that this method based on calibrated correlations can be applied as a reliable tool for flow analysis and parameter variation during the design phase for a wide range of compressor configurations.

scholarly journals CFD Study of Nozzle Configurations for Ultra High Bypass Engines

1993 ◽  
Author(s):  
H. Zimmermann ◽  
R. Gumucio ◽  
K. Katheder ◽  
A. Jula
Keyword(s):  
Engine Performance ◽  
Operating Conditions ◽  
Aerodynamic Design ◽  
Thrust Coefficient ◽  
Optimum Range ◽  
Installation Effects ◽  
Wide Range ◽  
And Performance ◽  
Aircraft Aerodynamics ◽  
Bypass Ratio

Performance and aerodynamic aspects of ultra-high bypass ratio ducted engines have been investigated with an emphasis on nozzle aerodynamics. The interference with aircraft aerodynamics could not be covered. Numerical methods were used for aerodynamic investigations of geometrically different aft end configurations for bypass ratios between 12 and 18, this is the optimum range for long missions which will be important for future civil engine applications. Results are presented for a wide range of operating conditions and effects on engine performance are discussed. The limitations for higher bypass ratios than 12 to 18 do not come from nozzle aerodynamics but from installation effects. It is shown that using CFD and performance calculations an improved aerodynamic design can be achieved. Based on existing correlations, for thrust and mass-flow, or using aerodynamic tailoring by CFD and including performance investigations, it is possible to increase the thrust coefficient up to 1%.

Uncertainty Analysis of Inflow Conditions on an HPT Gas Turbine Nozzle: Effect on Particle Deposition

2020 ◽  
Author(s):  
R. Friso ◽  
N. Casari ◽  
M. Pinelli ◽  
A. Suman ◽  
F. Montomoli
Keyword(s):  
Gas Turbine ◽  
Energy Efficient ◽  
Gas Turbines ◽  
Particle Deposition ◽  
Operating Conditions ◽  
Wide Range ◽  
And Performance ◽  
Gas Turbine Nozzle ◽  
The Impact ◽  
Inflow Conditions

Abstract Gas turbines (GT) are often forced to operate in harsh environmental conditions. Therefore, the presence of particles in their flow-path is expected. With this regard, deposition is a problem that severely affects gas turbine operation. Components’ lifetime and performance can dramatically vary as a consequence of this phenomenon. Unfortunately, the operating conditions of the machine can vary in a wide range, and they cannot be treated as deterministic. Their stochastic variations greatly affect the forecasting of life and performance of the components. In this work, the main parameters considered affected by the uncertainty are the circumferential hot core location and the turbulence level at the inlet of the domain. A stochastic analysis is used to predict the degradation of a high-pressure-turbine (HPT) nozzle due to particulate ingestion. The GT’s component analyzed as a reference is the HPT nozzle of the Energy-Efficient Engine (E3). The uncertainty quantification technique used is the probabilistic collocation method (PCM). This work shows the impact of the operating conditions uncertainties on the performance and lifetime reduction due to deposition. Sobol indices are used to identify the most important parameter and its contribution to life. The present analysis enables to build confidence intervals on the deposit profile and on the residual creep-life of the vane.

Experimental Investigations of Pressure Drop in the Combustion Chamber of Gas Turbine

1989 ◽  
Author(s):  
Marek Dzida ◽  
Krzysztof Kosowski
Keyword(s):  
Pressure Drop ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Operating Conditions ◽  
Experimental Results ◽  
Experimental Investigations ◽  
Relative Pressure ◽  
Wide Range ◽  
Few Data

In bibliography we can find many methods of determining pressure drop in the combustion chambers of gas turbines, but there is only very few data of experimental results. This article presents the experimental investigations of pressure drop in the combustion chamber over a wide range of part-load performances (from minimal power up to take-off power). Our research was carried out on an aircraft gas turbine of small output. The experimental results have proved that relative pressure drop changes with respect to fuel flow over the whole range of operating conditions. The results were then compared with theoretical methods.

Index-Based Performance Assessment and Condition Monitoring of a Mobile Working Machine

2005 ◽  
Author(s):  
Vesa Ho¨ltta¨ ◽  
Matti Repo ◽  
Lauri Palmroth ◽  
Aki Putkonen
Keyword(s):  
Performance Assessment ◽  
Condition Monitoring ◽  
Operating Conditions ◽  
Multidimensional Data ◽  
Technical Performance ◽  
Machine Performance ◽  
Wide Range ◽  
Data Driven Approach ◽  
And Performance ◽  
Mobile Working

Real-time performance assessment and condition monitoring are potential new features in mobile working machines that have to run in a wide range of operating conditions. Condition monitoring and performance assessment are needed to be able to proactively correct impending faults before severe failures or machine stoppage occur. This paper presents a data-driven approach for machine performance assessment and condition monitoring based on indices representing the performance of a subsystem. Instead of adding new sensors, the indices are computed using existing data from the machine control system. Metrics for machine performance follow-up are derived from these multidimensional data, which have strong nonlinear correlations in certain measurement variables. Although the indices describe primarily the technical performance of the machine, they have proven to be valuable also in terms of condition monitoring of various machine functions. The indices summarize in a concise and easily comprehensible manner changes in performance.

Unsteady Flow Structure and Global Variables in a Centrifugal Pump

2006 ◽  
Vol 128 (5) ◽  
pp. 937-946 ◽  
Author(s):  
José González ◽  
Carlos Santolaria
Keyword(s):  
Unsteady Flow ◽  
Centrifugal Pump ◽  
Flow Structure ◽  
Flow Model ◽  
Stokes Equations ◽  
Flow Analysis ◽  
Operating Conditions ◽  
Local Flow ◽  
Global Variables ◽  
Wide Range

A relationship between the global variables and the dynamic flow structure numerically obtained for a low specific speed centrifugal pump is presented in this paper. A previously developed unsteady flow model is used to correlate the dynamic field with the flow characteristics inside the impeller and volute of a single-stage commercial pump. Actually, the viscous incompressible Navier-Stokes equations are solved within a 3D unsteady flow model. A sliding mesh technique is applied to take into account the impeller-volute interaction. After the numerical model has been successfully compared with the experimental data for the unsteady pressure fluctuations pattern in the volute shroud, a new step is proposed in order to correlate the observed effects with the flow structure inside the pump. In particular, the torque as a function of the relative position of the impeller blades is related to the blades loading, and the secondary flow in the volute is related to the different pressure patterns numerically obtained. Local flow analysis and qualitative study of the helicity in different volute sections is performed. The main goal of the study presented is the successful correlation of local and global parameters for the flow in a centrifugal pump. The pressure forces seem to be the main driven mechanism to establish the flow features both in the impeller and volute, for a wide range of operating conditions.

Experimental Investigations on a PEMFC at Sub-Freezing Temperatures

2008 ◽  
Author(s):  
E. Pinton ◽  
Y. Fourneron ◽  
S. Rosini ◽  
L. Antoni
Keyword(s):  
Fuel Cell ◽  
Single Cells ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Ice Formation ◽  
Cathode Layer ◽  
Experimental Investigations ◽  
Operating Voltage ◽  
Initial Water ◽  
Wide Range

Ice/frost formation in a Proton Exchange Membrane Fuel Cell (PEMFC) operating under sub-zero temperatures can lead to its shutdown during start up. Isothermal potentiostatic and galvanostatic tests were performed on 220 cm2 single cells under a wide range of operating conditions in order to investigate the “cold start” behaviour. Different parameters have been investigated: the initial water contained in the membrane, the operating voltage, the cell temperature and current. An optimal wetting level of the fuel cell (FC) core for which cumulated heat generated by the electrochemical reaction is maximal, has been observed. Water management analysis from the membrane coupled with cell resistance measurement allowed to formulating a phenomenological interpretation of the overall performance evolution of the FC. FC starving is not only due to ice formation in the cathode layer pores, thus hindering oxygen transport. It is also due to ice formation in active reaction sites increasing the electrical resistance of the cell. Both factors dramatically reduce FC performance under load. The relative balance of each effect has been assessed.

scholarly journals Condition Monitoring for the Roller Bearings of Wind Turbines under Variable Working Conditions Based on the Fisher Score and Permutation Entropy

Energies ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 3085 ◽  
Author(s):  
Lei Fu ◽  
Tiantian Zhu ◽  
Kai Zhu ◽  
Yiling Yang
Keyword(s):  
Condition Monitoring ◽  
Wind Turbines ◽  
Operating Conditions ◽  
Machine Learning Algorithms ◽  
Identification Accuracy ◽  
Permutation Entropy ◽  
Experimental Investigations ◽  
Fisher Score ◽  
Vibrational Signal ◽  
Wide Range

Condition monitoring is used to assess the reliability and equipment efficiency of wind turbines. Feature extraction is an essential preprocessing step to achieve a high level of performance in condition monitoring. However, the fluctuating conditions of wind turbines usually cause sudden variations in the monitored features, which may lead to an inaccurate prediction and maintenance schedule. In this scenario, this article proposed a novel methodology to detect the multiple levels of faults of rolling bearings in variable operating conditions. First, signal decomposition was carried out by variational mode decomposition (VMD). Second, the statistical features were calculated and extracted in the time domain. Meanwhile, a permutation entropy analysis was conducted to estimate the complexity of the vibrational signal in the time series. Next, feature selection techniques were applied to achieve improved identification accuracy and reduce the computational burden. Finally, the ranked feature vectors were fed into machine learning algorithms for the classification of the bearing defect status. In particular, the proposed method was performed over a wide range of working regions to simulate the operational conditions of wind turbines. Comprehensive experimental investigations were employed to evaluate the performance and effectiveness of the proposed method.

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