Impact of Time-Resolved Entropy Measurement on a One-and-One-Half-Stage Axial Turbine Performance

2011 ◽  
Vol 134 (2) ◽  
Author(s):  
M. Mansour ◽  
N. Chokani ◽  
A. I. Kalfas ◽  
R. S. Abhari
Keyword(s):  
Fast Response ◽  
Loss Coefficient ◽  
Time Resolved ◽  
Axial Turbine ◽  
Pressure Loss Coefficient ◽  
Entropy Measurement ◽  
High Pressure Stage ◽  
Turbine Design ◽  
The Impact ◽  
Loss Mechanisms

An accurate assessment of unsteady interactions in turbines is required, so that this may be taken into account in the design of the turbine. This assessment is required since the efficiency of the turbine is directly related to the contribution of unsteady loss mechanisms. This paper presents unsteady entropy measurements in an axial turbine. The measurements are conducted at the rotor exit of a one–and-one-half-stage unshrouded turbine that is representative of a highly loaded, high-pressure stage of an aero-engine. The unsteady entropy measurements are obtained using a novel miniature fast-response probe, which has been developed at ETH Zurich. The entropy probe has two components: a one-sensor fast-response aerodynamic probe and a pair of thin-film gauges. The probe allows the simultaneous measurement of the total temperature and the total pressure from which the time-resolved entropy field can be derived. The measurements of the time-resolved entropy provide a new insight into the unsteady loss mechanisms that are associated with the unsteady interaction between rotor and stator blade rows. A particular attention is paid to the interaction effects of the stator wake interaction, the secondary flow interaction, and the potential field interaction on the unsteady loss generation at the rotor exit. Furthermore, the impact on the turbine design of quantifying the loss in terms of the entropy loss coefficient, rather than the more familiar pressure loss coefficient, is discussed in detail.

Impact of Time-Resolved Entropy Measurement on a One-and-1/2-Stage Axial Turbine Performance

2008 ◽  
Author(s):  
M. Mansour ◽  
N. Chokani ◽  
A. I. Kalfas ◽  
R. S. Abhari
Keyword(s):  
Fast Response ◽  
Loss Coefficient ◽  
Time Resolved ◽  
Axial Turbine ◽  
Pressure Loss Coefficient ◽  
Entropy Measurement ◽  
High Pressure Stage ◽  
Turbine Design ◽  
The Impact ◽  
Loss Mechanisms

An accurate assessment of unsteady interactions in turbines is required, so that this may be taken into account in the design of the turbine. This assessment is required since the efficiency of the turbine is directly related to the contribution of unsteady loss mechanisms. This paper presents unsteady entropy measurements in an axial turbine. The measurements are conducted at the rotor exit of a one-and-1/2-stage, unshrouded turbine that is representative of a highly loaded, high-pressure stage of an aero-engine. The unsteady entropy measurements are obtained using a novel miniature fast-response probe, which has been developed at ETH Zurich. The entropy probe has two components: a one-sensor fast response aerodynamic probe and a pair of thin-film gauges. The probe allows the simultaneous measurement of total temperature and total pressure from which the time-resolved entropy field can be derived. The measurements of the time resolved entropy provide a new insight into the unsteady loss mechanisms that are associated with the unsteady interaction between rotor and stator blade rows. A particular attention is paid to the interaction effects of the stator wake interaction, the secondary flow interaction and the potential field interaction on the unsteady loss generation at the rotor exit. Furthermore, the impact on turbine design of quantifying the loss in terms of the entropy loss coefficient, rather than the more familiar pressure loss coefficient, is discussed in detail.

Effect of Hot Streak Migration on Unsteady Blade Row Interaction in an Axial Turbine

2012 ◽  
Vol 134 (5) ◽  
Author(s):  
P. Jenny ◽  
C. Lenherr ◽  
R. S. Abhari ◽  
A. Kalfas
Keyword(s):  
Hot Spot ◽  
Fast Response ◽  
Secondary Flows ◽  
Inlet Temperature ◽  
Time Resolved ◽  
Axial Turbine ◽  
Blade Row ◽  
Hot Streak ◽  
The Impact ◽  
Blade Row Interaction

This paper presents an experimental study of the effect of unsteady blade row interaction on the migration of hot streaks in an axial turbine. The hot streaks can cause localized hot spots on the blade surfaces in a high-pressure turbine, leading to high heat loads and potentially catastrophic failure of the blades. An improved understanding of the effect of unsteady blade row interaction on an inlet temperature distortion is of crucial importance. The impact of hot streaks on the aerodynamic performance of a turbine stage is also not well understood. In the current experiment, the influence of hot streaks on a highly loaded 1.5-stage unshrouded model axial turbine is studied. A hot streak generator has been developed specifically for this project to introduce hot streaks that match the dimensional parameters of real engines. The temperature profile, spanwise position, circumferential position, and cross-section shape of the hot streak can be independently varied. The recently developed ETH Zurich two-sensor high temperature (260 °C) fast response aerodynamic probe (FRAP) technique and the fast response entropy. Probe (FENT) systems are used in this experimental campaign. Time resolved measurements of the unsteady pressure, temperature, and entropy are made at the NGV inlet and between the rotor and stator blade rows. From the nozzle guide vane inlet to outlet the measurements show a reduction in the maximum relative entropy difference between the free stream and the hot spot of 30% for the highest temperature gases in the core of the hot streak, indicating a region of heat loss. Time resolved flow field measurements at the rotor exit based on both measurement methods showed the hot gases traveling towards the hub and tip casing on the blade pressure side and interacting with secondary flows such as the hub passage vortex.

Effect of Hot Streak Migration on Unsteady Blade Row Interaction in an Axial Turbine

2010 ◽  
Author(s):  
P. Jenny ◽  
C. Lenherr ◽  
A. Kalfas ◽  
R. S. Abhari
Keyword(s):  
Hot Spot ◽  
Fast Response ◽  
Secondary Flows ◽  
Inlet Temperature ◽  
Time Resolved ◽  
Axial Turbine ◽  
Blade Row ◽  
Hot Streak ◽  
The Impact ◽  
Blade Row Interaction

This paper presents an experimental study of the effect of unsteady blade row interaction on the migration of hot streaks in an axial turbine. The hot streaks can cause localised hot spots on the blade surfaces in a high-pressure turbine, leading to high heat loads and potentially catastrophic failure of the blades. An improved understanding of the effect of unsteady blade row interaction on an inlet temperature distortion is of crucial importance. The impact of hot streaks on the aerodynamic performance of a turbine stage is also not well understood. In the current experiment, the influence of hot streaks on a highly loaded one-and-half-stage unshrouded model axial turbine is studied. A hot streak generator has been developed specifically for this project to introduce hot streaks that match the dimensional parameters of real engines. The temperature profile, spanwise position, circumferential position and cross-section shape of the hot streak can be independently varied. The recently developed ETH Zurich 2-sensor high temperature (260°C) Fast Response Aerodynamic Probe (FRAP) technique and the Fast Response Entropy Probe (FENT) systems are used in this experimental campaign. Time resolved measurements of the unsteady pressure, temperature and entropy are made at the NGV inlet and between the rotor and stator blade rows. From the nozzle guide vane inlet to outlet the measurements show a reduction in the maximum relative entropy difference between the free stream and the hot spot of 30% for the highest temperature gases in the core of the hot streak, indicating a region of heat loss. Time resolved flow field measurements at the rotor exit based on both measurement methods showed the hot gases travelling towards the hub and tip casing on the blade pressure side and interacting with secondary flows such as the hub passage vortex.

An Advanced Usage of Meanline Loss Systems for Axial Turbine Design Optimisation

2013 ◽  
Author(s):  
Ivan Zhdanov ◽  
Stephan Staudacher ◽  
Sergey Falaleev
Keyword(s):  
Parameter Space ◽  
Design Parameter ◽  
Global Optimum ◽  
Axial Turbine ◽  
Turbine Performance ◽  
Framework Model ◽  
Optimal Values ◽  
Loss Systems ◽  
Turbine Design ◽  
The Impact

A comprehensive axial turbine framework model has been developed at the Institute of Aircraft Propulsion Systems, University of Stuttgart. It discovers the principles of a meanline optimisation and shows its advantages for quick prediction of optimal meanline parameters considering manufacturing, mechanical and aerodynamic requirements. The framework model can incorporate different loss correlations and compare their results for one and the same multi-dimensional design parameter space. A special attention is paid to the influence of loss correlations on optimal values of meanline parameters. It is shown that, although all loss correlation has their own global optimum of turbine performance in the multi-dimensional design parameter space, they are going to coincide if the requirements addressed to a turbine are considered and the turbine design constraints, e.g. a specified rotational speed, inlet diameter and etc., are applied. Thus, the more constraints in the design parameter space exist, the lower the impact of a loss correlation on optimal values of meanline parameters.

The Dynamics of the Vorticity Field in a Low Solidity Axial Turbine

2008 ◽  
Author(s):  
K. G. Barmpalias ◽  
A. I. Kalfas ◽  
N. Chokani ◽  
R. S. Abhari
Keyword(s):  
Current Trend ◽  
Three Dimensional ◽  
Fast Response ◽  
Secondary Flows ◽  
Vorticity Field ◽  
Time Resolved ◽  
Axial Turbine ◽  
Unsteady Interaction ◽  
Vorticity Transport ◽  
Highly Loaded

A current trend in turbomachinery design is the use of low solidity axial turbines that can generate a given power with fewer blades. However, due to the higher turning of the flow, relative to a high solidity turbine, there is an increase in secondary flows and their associated losses. In order to increase the efficiency of these more highly loaded stages, an improved understanding of the mechanisms related to the development, evolution and unsteady interaction of the secondary flows is required. An experimental investigation of the unsteady vorticity field in highly loaded stages of a research turbine is presented here. The research turbine facility is equipped with a two-stage axial turbine that is representative of the high-pressure section of a steam turbine. Steady and unsteady area measurements are performed, with the use of miniature pneumatic and fast response aerodynamic probes, in closely spaced planes at the exits of each blade row. In addition to the 3D total pressure flowfield, the multi-plane measurements allow the full three-dimensional time-resolved vorticity and velocity fields to be determined. These measurements are then used to describe the development, evolution and unsteady interaction of the secondary flows and loss generation. Particular emphasis is given to the vortex stretching term of the vorticity transport equation, which gives new insight into the vortex tilting and stretching that is associated with the secondary loss generation.

scholarly journals Evaluation of a 1 MW, 250 kW-hr Battery Energy Storage System for Grid Services for the Island of Hawaii

Energies ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 3367 ◽  
Author(s):  
Karl Stein ◽  
Moe Tun ◽  
Keith Musser ◽  
Richard Rocheleau
Keyword(s):  
Energy Storage ◽  
Data Collection ◽  
Storage System ◽  
Energy Storage System ◽  
Fast Response ◽  
Lessons Learned ◽  
Battery Energy Storage ◽  
Utility Company ◽  
Battery Energy ◽  
The Impact

Battery energy storage systems (BESSs) are being deployed on electrical grids in significant numbers to provide fast-response services. These systems are normally procured by the end user, such as a utility grid owner or independent power producer. This paper introduces a novel research project in which a research institution has purchased a 1 MW BESS and turned ownership over to a utility company under an agreement that allowed the institution to perform experimentation and data collection on the grid for a multi-year period. This arrangement, along with protocols governing experimentation, has created a unique research opportunity to actively and systematically test the impact of a BESS on a live island grid. The 2012 installation and commissioning of the BESS was facilitated by a partnership between the Hawaii Natural Energy Institute (HNEI) and the utility owner, the Hawaiian Electric and Light Company (HELCO). After the test period ended, HELCO continued to allow data collection (including health testing). In 2018, after 8500 equivalent cycles, the BESS continues to operate within specifications. HNEI continues to provide HELCO with expertise to aid with diagnostics as needed. Details about the BESS design, installation, experimental protocols, initial results, and lessons learned are presented in this paper.

Assessment of Unsteady Flows in Turbines

1992 ◽  
Vol 114 (1) ◽  
pp. 79-90 ◽  
Author(s):  
O. P. Sharma ◽  
G. F. Pickett ◽  
R. H. Ni
Keyword(s):  
Unsteady Flow ◽  
Three Dimensional ◽  
Flow Simulation ◽  
Experimental Investigations ◽  
Flow Parameters ◽  
Research Activities ◽  
Flow Features ◽  
Computational Fluid Dynamics Cfd ◽  
Turbine Design ◽  
The Impact

The impacts of unsteady flow research activities on flow simulation methods used in the turbine design process are assessed. Results from experimental investigations that identify the impact of periodic unsteadiness on the time-averaged flows in turbines and results from numerical simulations obtained by using three-dimensional unsteady Computational Fluid Dynamics (CFD) codes indicate that some of the unsteady flow features can be fairly accurately predicted. Flow parameters that can be modeled with existing steady CFD codes are distinguished from those that require unsteady codes.

Vibration suppression investigation and parametric design of tri-axle straight heavy truck with pitch-resistant hydraulically interconnected suspension

2021 ◽  
pp. 107754632110396
Author(s):  
Fei Ding ◽  
Jie Liu ◽  
Chao Jiang ◽  
Haiping Du ◽  
Jiaxi Zhou ◽  
...  
Keyword(s):  
Surface Area ◽  
Dynamic Load ◽  
Pressure Loss ◽  
Vibration Suppression ◽  
Parametric Design ◽  
Suspension System ◽  
Loss Coefficient ◽  
The Body ◽  
Impedance Matrix ◽  
Pressure Loss Coefficient

The vibration suppression of the proposed pitch-resistant hydraulically interconnected suspension system for the tri-axle straight truck is investigated, and the vibration isolation performances are parametrically designed to achieve smaller body vibration and tire dynamic load using increased pitch stiffness and optimized pressure loss coefficient. For the hydraulic subsystem, the transfer impedance matrix method is applied to derive the impedance matrix. These hydraulic forces are incorporated into the motion equations of mechanical subsystem as external forces according to relationships between boundary flow and mechanical state vectors. In terms of the additional mode stiffness/damping and suspension performance requirements, the cylinder surface area, accumulator pressure, and damper valve’s pressure loss coefficient are comprehensively tuned with parametric design technique and modal analysis method. It is found the isolation capacity is heavily dependent on installation scheme and fluid physical parameters. Especially, the surface area can be designed for the oppositional installation to separately raise pitch stiffness without increasing bounce stiffness. The pressure loss coefficients are tuned with design of experiment approach and evaluated using all conflict indexes with normalized dimensionless evaluation factors. The obtained numerical results indicate that the proposed pitch-resistant hydraulically interconnected suspension system can significantly inhibit both the body and tire vibrations with decreased suspension deformation, and the tire dynamic load distribution among wheel stations is also improved.

The Characteristics Study of Helium-Xenon Mixture in Closed Brayton Cycle for Space Nuclear Reactor Power

2018 ◽  
Author(s):  
Xie Yang ◽  
Lei Shi
Keyword(s):  
Physical Properties ◽  
Pressure Loss ◽  
Nuclear Reactor ◽  
Reactor Power ◽  
Loss Coefficient ◽  
Working Fluid ◽  
System Efficiency ◽  
Pressure Loss Coefficient ◽  
Molar Weight ◽  
Xenon Mixture

Differing from the adoption of helium as working fluid of closed Brayton cycle (CBC) for terrestrial high temperature gas cooled reactor (HTGR) power plants, helium-xenon mixture with a proper molar weight was recommended as working fluid for space nuclear reactor power with CBC conversion. It is essential to figure out how the component of helium-xenon mixture affects the net system efficiency, in order to provide reference for the selection of appropriate cycle working fluid. After a discussion of the physical properties of different helium-xenon mixtures, the related physical properties are studied to analyze their affection on the key parameters of CBC, including adiabatic coefficient, recuperator effectiveness and normalized pressure loss coefficient. Then the comprehensive thermodynamics of CBC net system efficiency is studied in detail considering different helium-xenon mixtures. The physical properties study reveals that at 0.7 MPa and 400 K, the adiabatic coefficient of helium-xenon mixture increases with increased molar weight, from 0.400 (pure helium) to 0.414 (pure xenon), while recuperator effectiveness firstly increases and then decreases with the increase of molar weight, and the normalized pressure loss coefficient increases monotonically with molar weight increases. The thermodynamic analysis results show that the adiabatic coefficient has less effect on the net system efficiency, while the net system efficiency increases with increased recuperator effectiveness, and the net system efficiency decreases with normalized pressure loss coefficient increases. Finally, the mixture of helium-8.6% xenon was adopted as working fluid, instead of pure helium, for ensuring less turbine mechanicals (turbine and compressor) stages, and resulting maximum recuperator effectiveness. At the given cold / hot side temperature of 400 / 1300 K, the net system efficiency can reach 29.18% theoretically.

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