scholarly journals Characterization of a Twin-Entry Radial Turbine under Pulsatile Flow Condition

2016 ◽  
Vol 2016 ◽  
pp. 1-15 ◽  
Author(s):  
Mahfoudh Cerdoun ◽  
Adel Ghenaiet
Keyword(s):  
Gas Turbines ◽  
Pressure Curve ◽  
Radial Turbine ◽  
Apparent Length ◽  
Actual Output ◽  
Aerodynamic Performances ◽  
Shaft Power ◽  
Scavenge Process ◽  
Low Entropy

In automotive applications radial gas turbines are commonly fitted with a twin-entry volute connected to a divided exhaust manifold, ensuring a better scavenge process owing to less interference between engines’ cylinders. This paper is concerned with the study of the unsteady performances related to the pulsating flows of a twin-entry radial turbine in engine-like conditions and the hysteresis-like behaviour during the pulses period. The results show that the aerodynamic performances deviate noticeably from the steady state and depend mainly on the time shifting between the actual output power and the isentropic power, which is distantly related to the apparent length. The maximum of efficiency and output shaft power are accompanied by low entropy generation through the shroud entry side, and their instantaneous behaviours tend to follow mainly the inlet total pressure curve. As revealed a billow is created by the interaction between the main flow and the infiltrated flow, affecting the flow incidence at rotor entry and producing high losses.

Performance Characterization of a Twin Scroll Volute for Turbocharging Applications

2018 ◽  
Author(s):  
Carlo Cravero ◽  
Mario La Rocca ◽  
Andrea Ottonello
Keyword(s):  
Experimental Data ◽  
Scientific Literature ◽  
Aerodynamic Performance ◽  
Operating Conditions ◽  
Automatic Design ◽  
Cfd Model ◽  
Radial Turbine ◽  
Wide Range ◽  
Partial Admission

The use of twin scroll volutes in radial turbine for turbocharging applications has several advantages over single passage volute related to the engine matching and to the overall compactness. Twin scroll volutes are of increasing interest in power unit development but the open scientific literature on their performance and modelling is still quite limited. In the present work the performance of a twin scroll volute for a turbocharger radial turbine are investigated in some detail in a wide range of operating conditions at both full and partial admission. A CFD model for the volute have been developed and preliminary validated against experimental data available for the radial turbine. Then the numerical model has been used to generate the database of solutions that have been investigated and used to extract the performance. Different parameters and indices are introduced to describe the volute aerodynamic performance in the wide range of operating conditions chosen. The above parameters can be used for volute development or matching with a given rotor or efficiently implemented in automatic design optimization strategies.

Numerical Characterization of Flow and Heat Transfer in Pre-Swirl Systems

2017 ◽  
Author(s):  
Riccardo Da Soghe ◽  
Cosimo Bianchini ◽  
Jacopo D’Errico
Keyword(s):  
Heat Transfer ◽  
Gas Turbines ◽  
Numerical Study ◽  
Physical Phenomenon ◽  
Computational Procedure ◽  
Operating Conditions ◽  
Simulation Techniques ◽  
Numerical Characterization ◽  
Unsteady Simulation

This paper deals with a numerical study aimed at the validation of a computational procedure for the aerothermal characterization of pre-swirl systems employed in axial gas turbines. The numerical campaign focused on an experimental facility which models the flow field inside a direct-flow pre-swirl system. Steady and unsteady simulation techniques were adopted in conjunction with both a standard two-equations RANS/URANS modelling and more advanced approaches such as the Scale-Adaptive-Simulation principle, the SBES and LES. The comparisons between CFD and experiments were done in terms of swirl number development, static and total pressure distributions, receiving holes discharge coefficient and heat transfer on the rotor disc surface. Several operating conditions were accounted for, spanning 0.78·106<Reφ<1.21·106 and 0.123<λt<0.376. Overall the steady-state CFD predictions are in good agreement with the experimental evidences even though it is not able to confidently mimic the experimental swirl and pressure behaviour in some regions. Although the use of unsteady sliding mesh and direct turbulence modelling, would in principle increase the insight in the physical phenomenon, from a design perspective the tradeoff between accuracy and computational costs is not always favourable.

scholarly journals Estimation and Mitigation of Unknown Airplane Installation Effects on GPA Diagnostics

Machines ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 36
Author(s):  
Mikael Stenfelt ◽  
Konstantinos Kyprianidis
Keyword(s):  
Design Process ◽  
Gas Turbines ◽  
Diagnostic System ◽  
Power Extraction ◽  
Installation Effects ◽  
Degradation Pattern ◽  
Shaft Power ◽  
Air Intake ◽  
Intake Pressure ◽  
Diagnostic Framework

In gas turbines used for airplane propulsion, the number of sensors are kept at a minimum for accurate control and safe operation. Additionally, when data are communicated between the airplane main computer and the various subsystems, different systems may have different constraints and requirements regarding what data transmit. Early in the design process, these parameters are relatively easy to change, compared to a mature product. If the gas turbine diagnostic system is not considered early in the design process, it may lead to diagnostic functions having to operate with reduced amount of data. In this paper, a scenario where the diagnostic function cannot obtain airplane installation effects is considered. The installation effects in question is air intake pressure loss (pressure recovery), bleed flow and shaft power extraction. A framework is presented where the unknown installation effects are estimated based on available data through surrogate models, which is incorporated into the diagnostic framework. The method has been evaluated for a low-bypass turbofan with two different sensor suites. It has also been evaluated for two different diagnostic schemes, both determined and underdetermined. Results show that, compared to assuming a best-guess constant-bleed and shaft power, the proposed method reduce the RMS in health parameter estimation from 26% up to 80% for the selected health parameters. At the same time, the proposed method show the same degradation pattern as if the installation effects were known.

Ash Behavior During Combustion and Deposition in Coal-Fueled Gas Turbines

1987 ◽  
Vol 109 (3) ◽  
pp. 325-330 ◽  
Author(s):  
C. L. Spiro ◽  
S. G. Kimura ◽  
C. C. Chen
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Alkali Metals ◽  
Coal Ash ◽  
Water Mixture ◽  
Corrosion Rates ◽  
Petroleum Fuels

Chemical and physical transformations of coal ash during combustion and deposition in gas turbine environments have been studied. Extensive characterization of the coal-water mixture fuel and deposits obtained on deposition pins and turbine nozzle vanes has been performed. The behavior of alkali metals has been found to be much different from that for petroleum fuels, resulting in lower than expected deposition and probable reduced corrosion rates.

DEVELOPMENT AND APPLICATION OF A CONCENTRATION PROBE FOR MIXING FLOWS TRACKING IN TURBOMACHINERY APPLICATIONS

2021 ◽  
pp. 1-35
Author(s):  
Giulia Babazzi ◽  
Tommaso Bacci ◽  
Alessio Picchi ◽  
Tommaso Fodelli ◽  
Tommaso Lenzi ◽  
...  
Keyword(s):  
Gas Turbines ◽  
Thermal Field ◽  
Oxygen Sensor ◽  
Point Of View ◽  
Interface Plane ◽  
Tracer Gas ◽  
Precise Knowledge ◽  
Detailed Evaluation ◽  
Detection Unit

Abstract Modern gas turbines present important temperature distortions in the core-engine flowpath, mainly in the form of hot and cold streaks. As they highly influence turbines performance and lifetime, the precise knowledge of the thermal field evolution through the combustor and the high-pressure turbine is fundamental. The majority of past studies investigated streaks migrations directly examining the thermal field, while a limited amount of experimental work employed approaches based on the detection of tracer gases. The latter approach provides a more detailed evaluation of the evolution and mixing of the different flows. However, the slow time response due to the employment of sampling probes and gas analysers make the investigation extremely time consuming. In this study a commercial oxygen sensor element and its excitation/detection unit were integrated into a newly developed probe to carry out local tracer gas concentration measurements exploiting the fluorescence behaviour. The paper summarizes the probe development and calibration activities, with the characterization of its accuracy for different flow conditions. Finally, two probe applications are described: firstly the probe was used to detect tracer gas concentrations on a jet flow; afterwards it was traversed on the interface plane between a non-reactive, lean combustor simulator and the NGV cascade. The probe has proven to provide accurate and reliable measurements both from a quantitative and qualitative point of view even in highly 3D flow fields typical of gas turbines conditions.

Development of NiCrAlY Alloys for Corrosion-Resistant Coatings and Thermal Barrier Coatings of Gas Turbine Components

1999 ◽  
Vol 121 (4) ◽  
pp. 384-387 ◽  
Author(s):  
H. Nickel ◽  
D. Clemens ◽  
W. J. Quadakkers ◽  
L. Singheiser
Keyword(s):  
Gas Turbines ◽  
Steel Substrate ◽  
Free Standing ◽  
Protective Properties ◽  
Mcraly Coatings ◽  
Energy Conversion Systems ◽  
Corrosion Resistant Coatings ◽  
Low Pressure Plasma Spraying ◽  
Systematic Composition

The demand for improved efficiency and power output of energy conversion systems has lead to an increase of gas inlet temperatures in modern land-based gas turbines. The resulting increase of component surface temperature leads to an enhanced oxidation attack of the blade coating, which, in stationary gas turbines, is usually of the MCrAlY (with M = Co and/or Ni) type. Considerable efforts have been made in the improvement of the high temperature properties of MCrAlY coatings by additions of minor alloying elements. In the present paper, the effect of systematic composition variations, especially yttrium, silicon, and titanium additions, on the protective properties of MCrAlY coatings are presented. The coatings were applied to a steel substrate by low-pressure plasma spraying. Then, free-standing MCrAlY-bodies were machined from the coating. Isothermal and cyclic oxidation tests were carried out in the temperature range 950°C–1100°C. The effect of systematic variation of titanium and silicon contents on oxidation and micro structural stability was studied by characterization of the coating and the corrosion products using light and electron optical microscopy and by secondary neutrals mass spectrometry (SNMS).

The Characteristics of Radial Turbines for Small Gas Turbines

2003 ◽  
Author(s):  
C. Rodgers
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Structural Integrity ◽  
Velocity Ratio ◽  
Turbine Rotor ◽  
Flow Coefficient ◽  
Cycle Performance ◽  
Radial Turbine ◽  
Auxiliary Power Units ◽  
Axial Turbines

Inward flow radial and mixed flow turbines are effectively utilized in both small gas turbine auxiliary power units (APU’s) and turbochargers, where moderately high levels of efficiency can be readily attained with simple cast components, less sensitive to blade end-gap clearances than axial turbines. This paper provides an overview of radial turbine performance characteristics for small gas turbine applications as basically influenced by specific speed, velocity ratio, exit flow coefficient, and rotor tip to exducer root mean square (RMS) diameter ratio. Since turbine rotor mass and inertia play important roles in structural integrity and engine acceleration characteristics, the importance of turbine velocity ratio selection upon rotor tip diameter, and cycle performance are discussed. The effects of rotor reaction on radial turbine flow versus pressure characteristics are examined pertinent to engine matching requirements. Engine transient performance is addressed, as influenced by turbine operation towards and beyond runaway conditions.

STATISTICAL INFORMATION CHARACTERIZATION OF CONSERVED NON-CODING ELEMENTS IN VERTEBRATES

2007 ◽  
Vol 05 (02b) ◽  
pp. 533-547 ◽  
Author(s):  
I. ABNIZOVA ◽  
K. WALTER ◽  
R. TE BOEKHORST ◽  
G. ELGAR ◽  
W. R. GILKS
Keyword(s):  
Regulatory Function ◽  
Fugu Rubripes ◽  
Promoter Regions ◽  
Binding Motifs ◽  
High Entropy ◽  
Human Promoter ◽  
Puffer Fish ◽  
Information Pattern ◽  
Low Entropy

Recently, a set of highly conserved non-coding elements (CNEs) has been derived from a comparison between the genomes of the puffer fish, Takifugu or Fugu rubripes, and man. In order to facilitate the identification of these conserved elements in silico, we characterize them by a number of statistical features. We found a pronounced information pattern around CNE borders; although the CNEs themselves are AT rich and have high entropy (complexity), they are flanked by GC-rich regions of low entropy (complexity). We also identified the most abundant motifs within and around of CNEs, and identified those that group around their borders. Like in human promoter regions, the TBP, NF-Y and some other binding motifs are clustered around CNE boundaries, which may suggest a possible transcription regulatory function of CNEs.

Aerodynamic Design and Numerical Investigation on Overall Performance of a Micro Radial Turbine With Millimeter-Scale

2009 ◽  
Author(s):  
Lei Fu ◽  
Yan Shi ◽  
Qinghua Deng ◽  
Zhenping Feng
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Turbine Rotor ◽  
Rotor Blades ◽  
Micro Gas Turbine ◽  
Radial Turbine ◽  
Overall Performance ◽  
Low Reynolds ◽  
Exit Mach Number ◽  
Installation Technology

For millimeter-scale microturbines, the principal challenge is to achieve a design scheme to meet the aerothermodynamics, geometry restriction, structural strength and component functionality requirements while in consideration of the applicable materials, realizable manufacturing and installation technology. This paper mainly presents numerical investigations on the aerothermodynamic design, geometrical design and overall performance prediction of a millimeter-scale radial turbine with rotor diameter of 10mm. Four kinds of turbine rotor profiles were designed, and they were compared with one another in order to select the suitable profile for the micro radial turbine. The leaving velocity loss in micro gas turbines was found to be a large source of inefficiency. The approach of refining the geometric structure of rotor blades and the profile of diffuser were adopted to reduce the exit Mach number thus improving the total-static efficiency. Different from general gas turbines, micro gas turbines are operated in low Reynolds numbers, 104∼105, which has significant effect on flow separation, heat transfer and laminar to turbulent flow transition. Based on the selected rotor profile, several micro gas turbine configurations with different tip clearances of 0.1mm, 0.2mm and 0.3mm, respectively; two different isothermal wall conditions; and two laminar-turbulent transition models were investigated to understand the particular influence of low Reynolds number. These influences on the overall performance of the micro gas turbine were analyzed in details. The results indicate that these configurations should be included and emphasized during the design process of the millimeter-scale micro radial turbines.

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