scholarly journals Effects of ported shroud casing treatment on the acoustic and flow behaviour of a centrifugal compressor

2019 ◽  
Vol 21 (6) ◽  
pp. 998-1011 ◽  
Author(s):  
Sidharath Sharma ◽  
Jorge García-Tíscar ◽  
John M Allport ◽  
Simon Barrans ◽  
Ambrose K Nickson
Keyword(s):  
Gas Turbines ◽  
Acoustic Emissions ◽  
Aerodynamic Performance ◽  
Operating Conditions ◽  
Specific Power ◽  
Casing Treatment ◽  
Flow Features ◽  
Auxiliary Power Units ◽  
Ported Shroud ◽  
The Impact

Centrifugal turbomachines of smaller sizes operating at higher speeds have become pervasive due to the increased specific power and reliability achieved by improvements in manufacturing, materials and computational methods. The presence of these small turbomachines, specifically compressors, in helicopters, unmanned aerial vehicles, auxiliary power units, turbochargers and micro gas turbines necessitates superior aerodynamic performance over a broad operational range, which is widely achieved by ported shroud casing designs. In addition to aerodynamic performance, acoustic emissions have become a critical aspect of design for these small centrifugal compressors due to high operational speeds. Furthermore, the literature on the acoustic effects of the casing treatment is rather limited. Therefore, the impact of ported shroud casing treatment on the acoustic and flow features of the compressor operating at the design and near-surge conditions have been quantified by numerically modelling the open and blocked configuration of the compressors. Upon comparing with experimental results, the numerical spectra are shown to capture the differences between the two configurations at the investigated operating points with reasonable accuracy. Although the casing treatment is generally seen to decrease the overall acoustic emission of the compressor at both operating conditions, increased propagation of tonal content in the direction upstream to the impeller is observed, particularly for design operation. Broadband characteristics in the lower and medium frequency regions usually associated with near-surge operation including ‘whoosh’ noise are observed to be alleviated by the ported shroud casing treatment.

scholarly journals Evolution of flow characteristics in a centrifugal compressor with an increase in operating speed

2020 ◽  
pp. 146808742091660
Author(s):  
Sidharath Sharma ◽  
Jorge García-Tíscar ◽  
John M Allport ◽  
Simon Barrans ◽  
Ambrose K Nickson
Keyword(s):  
Gas Turbines ◽  
Acoustic Emissions ◽  
Flow Characteristics ◽  
Computing Methods ◽  
Specific Power ◽  
Operating Speed ◽  
Power Outputs ◽  
Acoustic Output ◽  
Ported Shroud ◽  
The Impact

Developments in materials, manufacturing and computing methods have catalysed the generation of efficient compressor designs with higher specific power outputs. Centrifugal compressors have become pervasive in environments demanding a combination of higher power with smaller sizes such as unmanned aerial vehicles, micro gas turbines and turbochargers. These compressors are expected to perform optimally in a range of operational speeds and mass flow states with low acoustic emissions. The impact of operating speed on the flow and acoustic characteristics of a ported shroud compressor has been explored in this work. The operation of the open and blocked configurations of the compressor at the design and near surge points each of a lower and a higher speedline was numerically and experimentally investigated. Comparing the results, the model was shown to predict the operation of the compressor for both configurations at the investigated operating points satisfactorily in terms of both performance and dominant acoustic features. With an increase in the velocity and the Mach number due to increased operational speed, changes in the flow behaviour in the inducer and diffuser were observed. An increase in operational speed was shown to generally increase the overall acoustic emission of the compressor for both configurations. The number of distinct tones in the acoustic output and their magnitude were also seen to be a function of operating speed.

Impact of Impeller Casing Treatment on the Acoustics of a Small High Speed Centrifugal Compressor

2018 ◽  
Author(s):  
Sidharath Sharma ◽  
Jorge García-Tíscar ◽  
John M. Allport ◽  
Martyn L. Jupp ◽  
Ambrose K. Nickson
Keyword(s):  
Centrifugal Compressor ◽  
High Speed ◽  
Pressure Fluctuations ◽  
Operating Conditions ◽  
Aerodynamic Noise ◽  
Noise Sources ◽  
Casing Treatment ◽  
Active Research ◽  
Ported Shroud ◽  
The Impact

Ported shroud casing treatment is widely used to delay the onset of surge and thereby enhancing the aerodynamic stability of a centrifugal compressor by recirculating the low momentum fluid in the blade passage. Performance losses associated with the use of recirculation casing treatment are well established in the literature and this is an area of active research. The other, less researched aspect of the casing treatment is its impact on the acoustics of the compressor. This work investigates the impact of ported shroud casing treatment on the acoustic characteristics of the compressor. The flow in two compressor configurations viz. with and without casing treatment operating at the design operating conditions of an iso-speed line are numerically modelled and validated with experimental data from gas stand measurements. The pressure fluctuations calculated as the flow solution are used to compute the spectral signatures at multiple locations to investigate the acoustic phenomenon associated with each configuration. Propagation of the frequency content through the ducts has been estimated with the aid of method of characteristics to enhance the content coming from the compressor. Expected tonal aerodynamic noise sources such as monopole (buzz-saw tones) and dipole (Blade Pass Frequency) are clearly identified in the acoustic spectra of the two configurations. The comparison of two configurations shows higher overall levels and tonal content in the case of a compressor with ported shroud operating at design conditions due to the presence of ‘mid-tones’.

Aerodynamic Design of a Ported Shroud Casing Treatment for a Turbocharger Compressor of a Miller-Cycle Gasoline Engine

2018 ◽  
Author(s):  
Christoph Schäfer ◽  
Mathias Bogner ◽  
Jan Ehrhard ◽  
Matthias Dunzer
Keyword(s):  
Mass Flow ◽  
Internal Combustion Engines ◽  
Specific Power ◽  
Boost Pressure ◽  
Engine Operation ◽  
Casing Treatment ◽  
Low Mass ◽  
Surge Line ◽  
Ported Shroud ◽  
The Impact

The emission laws for internal combustion engines become more and more strict. Therefore, new concepts have to be implemented. In the so called Miller approach the intake valve is closed before the intake stroke is finished, thus resulting in a lower combustion end temperature and pressure. As a negative result, the specific power of the engine is reduced. This disadvantage has to be compensated by an increased boost pressure delivered by a turbocharger compressor. For the turbomachinery this means for low end torque engine operation a compressor operating point at high pressure ratio and low mass flow. Thus an increased risk for surge results. A cost-effective measure to establish an utilizable compressor map in this regime is a ported shroud casing treatment. Here, a circumferential cavity connects the low channel at the inducer with the compressor housing inflow, allowing fluid to recirculate at low mass flows. Thereby, the gross inducer mass flow is increased, the flow stabilized and hence the surge line improved. In this paper, a ported shroud casing treatment is developed employing CFD. The aim is to improve the surge line as well as the stability of the compressor characteristics and to minimize the impact on compressor efficiencies at high flows as well as the acoustic behaviour at the same time. In order to validate the performance of the design, standard hot gas measurements as well as acoustic measurements are conducted and analyzed. Furthermore, the impact of a commonly applied 90° inflow bend on the performance of the ported shroud cavity is investigated by experimental data.

Impact of Operating Conditions and Design Parameters on Gas Turbine Hot Section Creep Life

2010 ◽  
Author(s):  
S. Eshati ◽  
M. F. Abdul Ghafir ◽  
P. Laskaridis ◽  
Y. G. Li
Keyword(s):  
Gas Turbines ◽  
Performance Model ◽  
Operating Conditions ◽  
Creep Model ◽  
Design Parameters ◽  
Gas Temperature ◽  
Creep Life ◽  
Cooling Effectiveness ◽  
Radial Temperature ◽  
The Impact

This paper investigates the relationship between design parameters and creep life consumption of stationary gas turbines using a physics based life model. A representative thermodynamic performance model is used to simulate engine performance. The output from the performance model is used as an input to the physics based model. The model consists of blade sizing model which sizes the HPT blade using the constant nozzle method, mechanical stress model which performs the stress analysis, thermal model which performs thermal analysis by considering the radial distribution of gas temperature, and creep model which using the Larson-miller parameter to calculate the lowest blade creep life. The effect of different parameters including radial temperature distortion factor (RTDF), material properties, cooling effectiveness and turbine entry temperatures (TET) is investigated. The results show that different design parameter combined with a change in operating conditions can significantly affect the creep life of the HPT blade and the location along the span of the blade where the failure could occur. Using lower RTDF the lowest creep life is located at the lower section of the span, whereas at higher RTDF the lowest creep life is located at the upper side of the span. It also shows that at different cooling effectiveness and TET for both materials the lowest blade creep life is located between the mid and the tip of the span. The physics based model was found to be simple and useful tool to investigate the impact of the above parameters on creep life.

Experimental investigation of isothermal and reacting flow characteristics downstream of axisymmetric bluff body stabilizers under stratified or fully premixed inlet mixture conditions

2020 ◽  
Author(s):  
Γεώργιος Πατεράκης
Keyword(s):  
Experimental Investigation ◽  
Turbulent Flow ◽  
Bluff Body ◽  
Operating Conditions ◽  
Reacting Flow ◽  
Wide Range ◽  
Flow Features ◽  
Air Mixing ◽  
The Impact ◽  
Stratified Flames

The current work describes an experimental investigation of isothermal and turbulent reacting flow field characteristics downstream of axisymmetric bluff body stabilizers under a variety of inlet mixture conditions. Fully premixed and stratified flames established downstream of this double cavity premixer/burner configuration were measured and assessed under lean and ultra-lean operating conditions. The aim of this thesis was to further comprehend the impact of stratifying the inlet fuelair mixture on the reacting wake characteristics for a range of practical stabilizers under a variety of inlet fuel-air settings. In the first part of this thesis, the isothermal mean and turbulent flow features downstream of a variety of axisymmetric baffles was initially examined. The effect of different shapes, (cone or disk), blockage ratios, (0.23 and 0.48), and rim thicknesses of these baffles was assessed. The variations of the recirculation zones, back flow velocity magnitude, annular jet ejection angles, wake development, entrainment efficiency, as well as several turbulent flow features were obtained, evaluated and appraised. Next, a comparative examination of the counterpart turbulent cold fuel-air mixing performance and characteristics of stratified against fully-premixed operation was performed for a wide range of baffle geometries and inlet mixture conditions. Scalar mixing and entrainment properties were investigated at the exit plane, at the bluff body annular shear layer, at the reattachment region and along the developing wake were investigated. These isothermal studies provided the necessary background information for clarifying the combustion properties and interpreting the trends in the counterpart turbulent reacting fields. Subsequently, for selected bluff bodies, flame structures and behavior for operation with a variety of reacting conditions were demonstrated. The effect of inlet fuel-air mixture settings, fuel type and bluff body geometry on wake development, flame shape, anchoring and structure, temperatures and combustion efficiencies, over lean and close to blow-off conditions, was presented and analyzed. For the obtained measurements infrared radiation, particle image velocimetry, laser doppler velocimetry, chemiluminescence imaging set-ups, together with Fouriertransform infrared spectroscopy, thermocouples and global emission analyzer instrumentation was employed. This helped to delineate a number of factors that affectcold flow fuel-air mixing, flame anchoring topologies, wake structure development and overall burner performance. The presented data will also significantly assist the validation of computational methodologies for combusting flows and the development of turbulence-chemistry interaction models.

Optimisation of CO Turndown for an Axially Staged Gas Turbine Combustor

2020 ◽  
Author(s):  
Jacob E. Rivera ◽  
Robert L. Gordon ◽  
Mohsen Talei ◽  
Gilles Bourque
Keyword(s):  
Residence Time ◽  
Parametric Study ◽  
Gas Turbines ◽  
Flow Reactor ◽  
Operating Conditions ◽  
Independent Effect ◽  
Inlet Temperature ◽  
Operating Characteristics ◽  
Two Stage ◽  
The Impact

Abstract This paper reports on an optimisation study of the CO turndown behaviour of an axially staged combustor, in the context of industrial gas turbines (GT). The aim of this work is to assess the optimally achievable CO turndown behaviour limit given system and operating characteristics, without considering flow-induced behaviours such as mixing quality and flame spatial characteristics. To that end, chemical reactor network modelling is used to investigate the impact of various system and operating conditions on the exhaust CO emissions of each combustion stage, as well as at the combustor exit. Different combustor residence time combinations are explored to determine their contribution to the exhaust CO emissions. The two-stage combustor modelled in this study consists of a primary (Py) and a secondary (Sy) combustion stage, followed by a discharge nozzle (DN), which distributes the exhaust to the turbines. The Py is modelled using a freely propagating flame (FPF), with the exhaust gas extracted downstream of the flame front at a specific location corresponding to a specified residence time (tr). These exhaust gases are then mixed and combusted with fresh gases in the Sy, modelled by a perfectly stirred reactor (PSR) operating within a set tr. These combined gases then flow into the DN, which is modelled by a plug flow reactor (PFR) that cools the gas to varying combustor exit temperatures within a constrained tr. Together, these form a simplified CRN model of a two-stage, dry-low emissions (DLE) combustion system. Using this CRN model, the impact of the tr distribution between the Py, Sy and DN is explored. A parametric study is conducted to determine how inlet pressure (Pin), inlet temperature (Tin), equivalence ratio (ϕ) and Py-Sy fuel split (FS), individually impact indicative CO turndown behaviour. Their coupling throughout engine load is then investigated using a model combustor, and its effect on CO turndown is explored. Thus, this aims to deduce the fundamental, chemically-driven parameters considered to be most important for identifying the optimal CO turndown of GT combustors. In this work, a parametric study and a model combustor study are presented. The parametric study consists of changing a single parameter at a time, to observe the independent effect of this change and determine its contribution to CO turndown behaviour. The model combustor study uses the same CRN, and varies the parameters simultaneously to mimic their change as an engine moves through its steady-state power curve. The latter study thus elucidates the difference in CO turndown behaviour when all operating conditions are coupled, as they are in practical engines. The results of this study aim to demonstrate the parameters that are key for optimising and improving CO turndown.

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.

The Effect of Alternative Turbine Cooling Schemes on the Performance of Utility Gas Turbine Powerplants

1982 ◽  
Author(s):  
Arthur Cohn ◽  
Mark Waters
Keyword(s):  
High Temperature ◽  
Gas Turbines ◽  
Power Plants ◽  
Heat Rate ◽  
Combined Cycle ◽  
Specific Power ◽  
Cooling Effectiveness ◽  
Turbine Cooling ◽  
The Impact ◽  
Systems Studies

It is important that the requirements and cycle penalties related to the cooling of high temperature turbines be thoroughly understood and accurately factored into cycle analyses and power plant systems studies. Various methods used for the cooling of high temperature gas turbines are considered and cooling effectiveness curves established for each. These methods include convection, film and transpiration cooling using compressor bleed and/or discharge air. In addition, the effects of chilling the compressor discharge cooling gas are considered. Performance is developed to demonstrate the impact of the turbine cooling schemes on the heat rate and specific power of Combined–Cycle power plants.

Power Augmentation Technologies for Gas Turbines: Alternatives for an Existing Simple Cycle Power Plant in Peru

2019 ◽  
Author(s):  
Cesar Celis ◽  
Sergio Peralta ◽  
Walter Galarza
Keyword(s):  
Power Plant ◽  
Power Output ◽  
Gas Turbines ◽  
Power Plants ◽  
Operating Conditions ◽  
Simple Cycle ◽  
Specific Power ◽  
Environmental Implications ◽  
Augmentation Techniques ◽  
Type Power

Abstract The influence of different power augmentation techniques used in gas turbines on the performance of simple cycle type power plants is assessed in this work. A computational model and tool realistically describing the performance of a typical simple cycle type power plant at design and off-design point conditions is initially developed. This tool is complemented with different models of power augmentation technologies. Finally, the whole model including both power plant and power augmentation techniques is used to analyze a case study involving a particular power plant in Peru. The results from the simulations of the specific power plant indicate that power output can be increased through all the evaluated power augmentation technologies. These results show indeed that technologies based on absorption refrigeration systems produce the largest gains in terms of power output (7.1%) and thermal efficiency (0.7%). Such results confirm the suitability of these systems for simple cycle type power plant configurations operating under hot and humid operating conditions as those accounted for here. From an economic perspective, considering the net present value as the key parameter defining the feasibility of a project in this category, power augmentation techniques based on absorption cooling systems result also the most suitable ones for the studied power plant. Power augmentation techniques environmental implications are also quantified in terms of CO2 emissions.

scholarly journals Industrial Gas Turbine Performance: Compressor Fouling and On-Line Washing

2014 ◽  
Vol 136 (10) ◽  
Author(s):  
Uyioghosa Igie ◽  
Pericles Pilidis ◽  
Dimitrios Fouflias ◽  
Kenneth Ramsden ◽  
Panagiotis Laskaridis
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Engine Performance ◽  
Operating Conditions ◽  
Compressor Cascade ◽  
Compressor Blades ◽  
Turbine Performance ◽  
Industrial Gas Turbines ◽  
On Line ◽  
The Impact

Industrial gas turbines are susceptible to compressor fouling, which is the deposition and accretion of airborne particles or contaminants on the compressor blades. This paper demonstrates the blade aerodynamic effects of fouling through experimental compressor cascade tests and the accompanied engine performance degradation using turbomatch, an in-house gas turbine performance software. Similarly, on-line compressor washing is implemented taking into account typical operating conditions comparable with industry high pressure washing. The fouling study shows the changes in the individual stage maps of the compressor in this condition, the impact of degradation during part-load, influence of control variables, and the identification of key parameters to ascertain fouling levels. Applying demineralized water for 10 min, with a liquid-to-air ratio of 0.2%, the aerodynamic performance of the blade is shown to improve, however most of the cleaning effect occurred in the first 5 min. The most effectively washed part of the blade was the pressure side, in which most of the particles deposited during the accelerated fouling. The simulation of fouled and washed engine conditions indicates 30% recovery of the lost power due to washing.

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