Comparative Studies of Alternative HPC Configurations for the NEWAC IRA Engine

2010 ◽  
Author(s):  
W. John Calvert ◽  
Ed Swain ◽  
Ian Woods ◽  
Mark Dempsey ◽  
Uwe Schmidt-Eisenlohr
Keyword(s):  
Axial Compressor ◽  
Flow Coefficient ◽  
Engine Exhaust ◽  
Radial Compressor ◽  
Advantages And Disadvantages ◽  
High Pressure Compressor ◽  
Core Concepts ◽  
Outlet Flow ◽  
Exhaust Stream ◽  
Set Up

One of the core configurations being considered under the EU NEWAC (NEWAero-engine Core concepts) programme is for an intercooled recuperative aero-engine (IRA). The IRA concept exploits the heat of the engine exhaust gas and maximises the heat pick up capacity of the combustor inlet air by intercooling in front of the high pressure compressor (HPC). The datum configuration adopted for the HPC is a single stage radial compressor, but comparative design studies into alternative configurations have also been carried out. The ducting arrangements for the HPC in the IRA engine are more complicated than in a conventional turbofan engine, with the inlet flow coming from the intercooler via a C-shaped duct and the outlet flow going to the heat exchangers in the exhaust stream via 8 pipes on the outside of the engine core. A radial compressor fits quite neatly into this configuration, but the size required for a 70,000 lbf (310kN) thrust engine is significantly larger than for existing designs. In addition, the use of intercooling reduces the flow coefficient below the optimum value. By contrast, an axial compressor is likely to achieve higher efficiency, but it will be longer and have considerably more aerofoils. Therefore, preliminary designs for axial, radial and axial-CF configurations have been set up and analysed using CFD and finite element methods to assess their aerodynamic performance and to investigate their mechanical requirements. Each configuration has some advantages and disadvantages, and the results from the current studies quantify these for current levels of compressor technology.

Surge in a Low-Speed Radial Compressor

1998 ◽  
Author(s):  
Corine Meuleman ◽  
Frank Willems ◽  
Rick de Lange ◽  
Bram de Jager
Keyword(s):  
Flow Rate ◽  
Pressure Rise ◽  
Flow Coefficient ◽  
Lumped Parameter Model ◽  
Pressure Oscillations ◽  
Vaned Diffuser ◽  
Flow Angle ◽  
Radial Compressor ◽  
Low Speed ◽  
Lumped Parameter

Surge is measured in a low-speed radial compressor with a vaned diffuser. For this system, the flow coefficient at surge is determined. This coefficient is a measure for the inducer inlet flow angle and is found to increase with increasing rotational speed. Moreover, the frequency and amplitude of the pressure oscillations during fully-developed surge are compared with results obtained with the Greitzer lumped parameter model. The measured surge frequency increases when the compressor mass flow is throttled to a smaller flow rate. Simulations show that the Greitzer model describes this relation reasonably well except for low rotational speeds. The predicted amplitude of the pressure rise oscillations is approximately two times too small when deep surge is met in the simulations. For classic surge, the agreement is worse. The amplitude is found to depend strongly on the shape of the compressor and throttle characteristic, which are not accurately known.

Perceived Advantages and Disadvantages of Nonsmoking Sections in Restaurants: Topics to Communicate to Restaurateurs

1989 ◽  
Vol 9 (4) ◽  
pp. 299-304 ◽  
Author(s):  
Gerardo Marin ◽  
Raymond J. Gamba
Keyword(s):  
San Francisco ◽  
Advantages And Disadvantages ◽  
Set Up

Results from interviews with 315 restaurateurs in San Francisco are reported on their perceptions of the advantages and disadvantages of having a nonsmoking section in their restaurants. The major advantage of having a nonsmoking section independent of whether one is present is to please customers. The most commonly mentioned disadvantage for those restaurants with nonsmoking sections is the fact that it is inconvenient to clients' seating preferences primarily because it breaks up dining parties. Efforts at convincing restaurateurs to set up nonsmoking sections may be directed at pointing out savings in cleaning, labor, insurance, and the improvement of the health of their employees together with meeting clients' desires.

Characteristics of Stable Rotating Stall Cells in an Axial Compressor

2017 ◽  
Author(s):  
Adam R. Hickman ◽  
Scott C. Morris
Keyword(s):  
Flow Field ◽  
High Speed ◽  
Pressure Ratio ◽  
Pressure Sensors ◽  
Axial Compressor ◽  
Field Measurements ◽  
Rotating Stall ◽  
Flow Coefficient ◽  
Stable Operation ◽  
Double Phase

Flow field measurements of a high-speed axial compressor are presented during pre-stall and post-stall conditions. The paper provides an analysis of measurements from a circumferential array of unsteady shroud static pressure sensors during stall cell development. At low-speed, the stall cell approached a stable size in approximately two rotor revolutions. At higher speeds, the stall cell developed within a short amount of time after stall inception, but then fluctuated in circumferential extent as the compressor transiently approached a stable post-stall operating point. The size of the stall cell was found to be related to the annulus average flow coefficient. A discussion of Phase-Locked Average (PLA) statistics on flow field measurements during stable operation is also included. In conditions where rotating stall is present, flow field measurements can be Double Phase-Locked Averaged (DPLA) using a once-per-revolution (1/Rev) pulse and the period of the stall cell. The DPLA method provides greater detail and understanding into the structure of the stall cell. DPLA data indicated that a stalled compressor annulus can be considered to contained three main regions: over-pressurized passages, stalled passages, and recovering passages. Within the over-pressured region, rotor passages exhibited increased blade loading and pressure ratio compared to pre-stall values.

Improved criteria for stall-free preliminary design of axial compressor of aero gas turbine engines

2018 ◽  
Vol 233 (9) ◽  
pp. 3286-3297 ◽  
Author(s):  
MR Aligoodarz ◽  
A Mehrpanahi ◽  
M Moshtaghzadeh ◽  
A Hashiehbaf
Keyword(s):  
Gas Turbine ◽  
Large Scale ◽  
Axial Compressor ◽  
Axial Flow ◽  
Design Criterion ◽  
Flow Coefficient ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Parameter Ranges ◽  
Axial Flow Compressors

A worldwide effort has been devoted to developing highly efficient and reliable gas turbine engines. There exist many prominent factors in the development of these engines. One of the most important features of the optimal design of axial flow compressors is satisfying the allowable range for various parameters such as flow coefficient, stage loading, the degree of reaction, De-Haller number, etc. But, there are some applicable cases that the mentioned criteria are exceeded. One of the most famous parameters is De-Haller number, which according to literature data should not be kept less than 0.72 in any stage of the axial compressor. A deep insight into the current small- or large-scale axial flow compressors shows that a discrepancy will occur among design criterion for De-Haller number and experimental measurements in which the De-Haller number is less than the design limit but no stall or surge is observed. In this paper, an improved formulation is derived based on one-dimensional modeling for predicting the stall-free design parameter ranges especially stage loading, flow coefficient, etc. for various combinations. It was found that the current criterion is much more accurate than the De-Haller criterion for design purposes.

Structural Analysis of a Gas Turbine Axial Compressor Blade Eroded by Online Water Washing

2020 ◽  
Author(s):  
Rossella Cinelli ◽  
Gianluca Maggiani ◽  
Serena Gabriele ◽  
Alessio Castorrini ◽  
Giuliano Agati ◽  
...  
Keyword(s):  
Structural Analysis ◽  
Gas Turbine ◽  
Axial Compressor ◽  
Compressor Blades ◽  
Performance Levels ◽  
Water Washing ◽  
Critical Issues ◽  
Air Intake ◽  
Set Up ◽  
The Impact

Abstract The Gas Turbine (GT) Axial Compressor (AXCO) can absorb up to the 30% of the power produced by the GT, being the component with the largest impact over the performances. The axial compressor blades might undergo the fouling phenomena as a consequence of the unwanted material locally accumulating during the machine operations. The presence of such polluting substances reduces the aerodynamic efficiency as well as the air intake causing the drop of performances and the increase of the fuel consumption. To address the above-mentioned critical issues, several washing strategies have been implemented so far, among the most promising ones, High Flow On-Line Water Washing (HFOLWW) is worth to mention. Exploiting this technique, the performance levels are preserved, whereas the stops for maintenance should be reduced. Nevertheless, this comes at the cost of a long-term erosion exposure caused by the impact of water washing droplets. Hence, it was deemed necessary to carry out a finite element method (FEM) structural analysis of the first rotor stage of the compressor of an aeroderivative GT, integrated into the HFOLWW scheme, in order to evaluate the fatigue strength of the component subjected to the erosion; possibly along with its acceptability limits. The first step requires the determination of the blade areas affected by erosion, using computational fluid dynamics (CFD) simulations, followed by the creation and the 3D modelling of the damaged geometry. The final step consists in the evaluation of the static stress and the dynamic agents, to perform a fatigue analysis through the Goodman relation and carrying out a simulation of damage propagation exploiting the theory of fracture mechanics. This procedure has been extended to the damage-free baseline component to set-up a model suitable for comparison. The structural analysis confirms the design of the blade, moreover dynamic and static evaluation of the eroded profiles haven’t outlined any working, nor mechanical, issue. This entitles the structural choice of HFOLWW as a system which guarantees full performance levels of the compressor.

Active Stabilization of Rotating Stall in a Three-Stage Axial Compressor

1993 ◽  
Author(s):  
Joel M. Haynes ◽  
Gavin J. Hendricks ◽  
Alan H. Epstein
Keyword(s):  
High Speed ◽  
Travelling Waves ◽  
Axial Compressor ◽  
Open Loop ◽  
Rotating Stall ◽  
Forced Response ◽  
Flow Coefficient ◽  
Design Parameters ◽  
Time Lags ◽  
Active Stabilization

A three-stage, low speed axial research compressor has been actively stabilized by damping low amplitude circumferentially travelling waves which can grow into rotating stall. Using a circumferential array of hot wire sensors, and an array of high speed individually positioned control vanes as the actuator, the first and second spatial harmonics of the compressor were stabilized down to a characteristic slope of 0.9, yielding an 8% increase in operating flow range. Stabilization of the third spatial harmonic did not alter the stalling flow coefficient. The actuators were also used open loop to determine the forced response behavior of the compressor. A system identification procedure applied to the forced response data then yielded the compressor transfer function. The Moore-Greitzer, 2-D, stability model was modified as suggested by the measurements to include the effect of blade row time lags on the compressor dynamics. This modified Moore-Greitzer model was then used to predict both the open and closed loop dynamic response of the compressor. The model predictions agreed closely with the experimental results. In particular, the model predicted both the mass flow at stall without control and the design parameters needed by, and the range extension realized from, active control.

Numerical Simulation of Particulates in Multistage Axial Compressors

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Swati Saxena ◽  
Giridhar Jothiprasad ◽  
Corey Bourassa ◽  
Byron Pritchard
Keyword(s):  
High Pressure ◽  
Axial Compressor ◽  
Airborne Particulate Matter ◽  
Spherical Particles ◽  
Nonspherical Particles ◽  
Qualitative Comparison ◽  
Axial Compressors ◽  
Sand Erosion ◽  
High Pressure Compressor ◽  
Pressure Compressor

Aircraft engines ingest airborne particulate matter, such as sand, dirt, and volcanic ash, into their core. The ingested particulate is transported by the secondary flow circuits via compressor bleeds to the high pressure turbine and may deposit resulting in turbine fouling and loss of cooling effectiveness. Prior publications focused on particulate deposition and sand erosion patterns in a single stage of a compressor or turbine. This work addresses the migration of ingested particulate through the high pressure compressor (HPC) and bleed systems. This paper describes a 3D CFD methodology for tracking particles along a multistage axial compressor and presents particulate ingestion analysis for a high pressure compressor section. The commercial CFD multiphase solver ANSYS CFX® has been used for flow and particulate simulations. Particle diameters of 20, 40, and 60 μm are analyzed. Particle trajectories and radial particulate profiles are compared for these particle diameters. The analysis demonstrates how the compressor centrifuges the particles radially toward the compressor case as they travel through the compressor; the larger diameter particles being more significantly affected. Nonspherical particles experience more drag as compared to spherical particles, and hence a qualitative comparison between spherical and nonspherical particles is shown.

CLASSIFICATION OF HAND SPLINTING

Hand Surgery ◽  
2002 ◽  
Vol 07 (02) ◽  
pp. 209-213 ◽  
Author(s):  
Simon K. M. Wong
Keyword(s):  
Environmental Factors ◽  
Classification System ◽  
Single System ◽  
Logical Deduction ◽  
Advantages And Disadvantages ◽  
American Society ◽  
Set Up ◽  
New System ◽  
Rote Memory

The terminology in describing splint or orthosis has been reviewed but there is no one single system adopted universally. Joint efforts by doctors, therapists and orthotists had been set up to review the classification of splint. Four ways of classifying hand splints have been introduced: namely, eponym, acronym, descriptive classification system and the classification system proposed by the American Society of Hand Therapists. These systems include the use of rote memory or logical deduction in grouping of splints. This paper describes the advantages and disadvantages of each classification system. Neither one of the systems stands out to be the best. A combination of the advantages of different systems, such as precision and logical deduction, may be an option for developing a new system. Moreover, communication, documentation and other environmental factors should also be considered.

Beak Trimming Handbook for Egg Producers

2006 ◽  
Author(s):  
Phil Glatz ◽  
Michael Bourke
Keyword(s):  
Quality Control ◽  
Best Practice ◽  
Egg Laying ◽  
Advantages And Disadvantages ◽  
Future Developments ◽  
Maximum Productivity ◽  
Comprehensive Information ◽  
Set Up ◽  
Beak Trimming ◽  
Farm Biosecurity

The Beak Trimming Handbook for Egg Producers is a straightforward, practical guide to beak trimming of egg-laying hens to minimise cannibalism. It provides comprehensive information on why birds peck and how pecking can lead to problems like cannibalism; the methods available to beak trim birds; why a particular method should be chosen; and at what age birds may be trimmed. The book addresses quality control of beak trimming, enabling egg producers to be confident that equipment is properly set up, that birds are handled and trimmed according to best practice and farm biosecurity is maintained. Management of birds following beak trimming, to protect of the welfare of the birds and to ensure maximum productivity, is covered in detail. Best-practice, current methods of beak trimming, costs of trimming and ways to reduce the use of trimming are examined, along with expected future developments. The advantages and disadvantages of beak trimming are fully explored, covering both public and industry attitudes to the operation. Alternatives to beak trimming are canvassed to understand how the use of fitted devices, enrichment devices, abrasives, low lighting and the choice of low-pecking strains of birds can reduce the need for beak trimming. Finally, the book discusses strategies for minimising cannibalism and how the chosen strategy may be documented and justified. Please note that this book is spiral-bound.

Electromagnetic Flowmeter Primary Elements

1959 ◽  
Vol 81 (4) ◽  
pp. 660-666 ◽  
Author(s):  
V. P. Head
Keyword(s):  
Reynolds Number ◽  
Rate Equation ◽  
Electromagnetic Flowmeter ◽  
Flow Coefficient ◽  
Electrically Conducting ◽  
Volume Rate ◽  
Set Up

An obstructionless flowmeter for electrically conducting liquids is described. Tentative design and inspection criteria which have been found to provide accuracies of ±1/2 per cent, or as little as ±0.005 fps pipeline velocity, are set up. A practical threshold conductivity of meterable liquids is set at 20 micromhos per cm, though there is every reason to believe this will be drastically cut with further progress. Above this threshold, the flow coefficient in the volume-rate equation is shown by tests to be independent of the conductivity, of the Reynolds number, and of installation conditions.

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