scholarly journals Dimensionless quantification of small radial turbine transient performance

2020 ◽  
Vol 235 (1) ◽  
pp. 188-198
Author(s):  
Qiyou Deng ◽  
Andrew Pennycott ◽  
Qingning Zhang ◽  
Calogero Avola ◽  
Ludek Pohorelsky ◽  
...  
Keyword(s):  
Dynamic Behaviour ◽  
Internal Flow ◽  
Simulation Studies ◽  
Dimensionless Parameters ◽  
Transient Behaviour ◽  
Response Characteristics ◽  
Radial Turbine ◽  
Housing Temperature ◽  
Turbine Housing ◽  
Modelling Approach

Turbochargers are inherently dynamic devices, comprising internal flow volumes, mechanical inertias and thermal masses. When operating under transient conditions within an engine system, these dynamics need to be better understood. In this paper, a new non-dimensional modelling approach to characterise the turbocharger is proposed. Two new dimensionless quantities are defined with respect to mechanical and thermal transient behaviour, which are used in conjunction with the Strouhal number for flow transients. The modelling approach is applied to a small wastegated turbocharger and validated against experimental results. The model is used to simulate the turbocharger mass flow rate, turbine housing temperature and shaft speed responses to different excitation frequencies for different sizes of turbine. The results highlight the influence of turbocharger size on the dynamic behaviour of the system, which is particularly marked for the turbine housing temperature. At certain frequency ranges, the system behaviour is quasi-steady, allowing modelling through static maps in these operating regions. Outside these ranges, however, transient elements play a more important role. The simulation study shows that the proposed dimensionless parameters can be used to normalise the influence of turbine size on the dynamic response characteristics of the system. The model and corresponding dimensionless parameters can be applied in future simulation studies as well as for turbocharger matching in industry.

Improved Performance of a Radial Turbine Through the Implementation of Back Swept Blading

2008 ◽  
Author(s):  
Liam Barr ◽  
Stephen W. T. Spence ◽  
Paul Eynon
Keyword(s):  
Numerical Study ◽  
Numerical Models ◽  
Internal Flow ◽  
Turbine Rotor ◽  
Point Of View ◽  
Blade Angle ◽  
Element Analysis ◽  
Numerical Predictions ◽  
Radial Turbine ◽  
Optimum Velocity

This report details the numerical investigation of the performance characteristics and internal flow fields of an 86 mm radial turbine for a turbocharger application. A new blade was subsequently designed for the 86 mm rotor which departed from the conventional radial inlet blade angle to incorporate a 25° inlet blade angle. A comparative analysis between the two geometries is presented. Results show that the 25° back swept blade offers significant increases in efficiency while operating at lower than optimum velocity ratios (U/C). This enhanced efficiency at off-design conditions would significantly improve turbocharger performance where the turbine typically experiences lower than optimum velocity ratios while accelerating during engine transients. A commercial CFD code was used to construct single passage steady state numerical models. The numerical predictions show off-design performance gains of 2% can be achieved, while maintaining design point efficiency. Primary and secondary flow patterns are examined at various planes within the turbine blade passage and reasons for the increase in performance are discussed. A finite element analysis has been conducted to assess the stress implications of introducing a non-radial angle at turbine rotor inlet. A modal analysis was also carried out in order to identify the natural frequencies of the turbine geometry, thus calculating the critical speeds corresponding to the induction of the excitational frequencies from the stator vanes. Although the new blade design has resulted in stress increases in some regions, the numerical study has shown that it is feasible from both an aerodynamic and structural point of view to increase the performance characteristic of a radial turbine through the implementation of back swept blading.

scholarly journals Dynamic Behaviour Adaptation of Lightweight Structures by Compressible Constrained Layer Damping with Embedded Polymeric Foams and Nonwovens

2019 ◽  
Vol 9 (17) ◽  
pp. 3490 ◽  
Author(s):  
Tom Ehrig ◽  
Klaudiusz Holeczek ◽  
Niels Modler ◽  
Pawel Kostka
Keyword(s):  
Intermediate Layer ◽  
Dynamic Behaviour ◽  
Constrained Layer Damping ◽  
Polymeric Foams ◽  
Lightweight Structures ◽  
Crucial Component ◽  
Theoretical Assumptions ◽  
Original Concept ◽  
Better Than ◽  
Modelling Approach

Evanescent morphing in combination with an original concept of Compressible Constrained Layer Damping (CCLD) is a novel and promising approach for dynamic behaviour adaptation. The crucial component of the CCLD is a compressible intermediate layer with its thickness and material properties controlled by fluid actuation, enabling the adjustment of the damping and stiffness of the overall system. To estimate the potential of the CCLD, an analytical model was developed which describes the vibration behaviour of the overall structure, taking into account the compression-driven properties of the intermediate layer. The results confirm the principal correctness of the initial theoretical assumptions regarding the adaptive dynamic behaviour of structures with CCLD treatment. A significant vibration mitigation as well as a high adaptability of dynamic behaviour were observed, however, they show a complex dependence on the system configuration. Nevertheless, the developed analytical modelling approach can already be used for a preliminary system design. Besides the analysed polymer-based foams as the intermediate layer, nonwovens also exhibit compression-dependent shear properties and can therefore be used in CCLD. First preliminary investigations show that the damping performance is on average about ten times better than that of the polymeric foams.

Long-term Macroeconomic Dynamics of Competition in the Russian Economy using Agent- based Modelling

2017 ◽  
Vol 6 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Tatyana Eftonova ◽  
Mariam Kiran ◽  
Mike Stannett
Keyword(s):  
Dynamic Behaviour ◽  
Economic Modelling ◽  
Macroeconomic Dynamics ◽  
Agent Based ◽  
Economic Agents ◽  
Agent Based Modelling ◽  
Russian Economy ◽  
Modelling Techniques ◽  
Modelling Approach

Agent-based economic modelling techniques are increasingly being used to complement standard economic simulations. This paper re-models a standard equation-based simulation model of the Russian macroeconomy in an agent-based setup, and uses it to investigate the effect that antimonopoly legislation can be expected to have upon long-term dynamic behaviour. The results reveal various potential outcomes which would have not been visible using traditional equation-based modelling techniques. While the number of economic agents has been kept deliberately small in the work presented here, the modelling approach is scalable to systems incorporating many millions of agents.

scholarly journals Properties of Switch-like Bioregulatory Networks Studied by Simulation of the Hypoxia Response Control System

2004 ◽  
Vol 15 (7) ◽  
pp. 3042-3052 ◽  
Author(s):  
Kurt W. Kohn ◽  
Joseph Riss ◽  
Olga Aprelikova ◽  
John N. Weinstein ◽  
Yves Pommier ◽  
...  
Keyword(s):  
Cellular Response ◽  
Synthesis Rate ◽  
Growth Factor Signaling ◽  
Simulation Studies ◽  
Response Control ◽  
Hypoxia Response ◽  
Von Hippel Lindau ◽  
Response Characteristics ◽  
Interaction Map ◽  
Conserved Core

A complex bioregulatory network could be more easily comprehended if its essential function could be described by a small “core” subsystem, and if its response characteristics were switch-like. We tested this proposition by simulation studies of the hypoxia response control network. We hypothesized that a small subsystem governs the basics of the cellular response to hypoxia and that this response has a sharp oxygen-dependent transition. A molecular interaction map of the network was prepared, and an evolutionarily conserved core subsystem was extracted that could control the activity of hypoxia response promoter elements on the basis of oxygen concentration. The core subsystem included the hypoxia-inducible transcription factor (HIFα:ARNT heterodimer), proline hydroxylase, and the von Hippel-Lindau protein. Simulation studies showed that the same core subsystem can exhibit switch-like responses both to oxygen level and to HIFα synthesis rate, thus suggesting a mechanism for hypoxia response promoter element-dependent responses common to both hypoxia and growth factor signaling. The studies disclosed the mechanism responsible for the sharp transitions. We show how parameter sets giving switch-like behavior can be found and how this type of behavior provides a foundation for quantitative studies in cells.

Aerodynamic Excitation Analysis of Radial Turbine Blades due to Unsteady Flow From Vaneless Turbine Housings

2017 ◽  
Author(s):  
Stephan Netzhammer ◽  
Damian M. Vogt ◽  
Stephan Kraetschmer ◽  
Johannes Leweux ◽  
Andreas Koengeter
Keyword(s):  
Test Data ◽  
Turbine Blades ◽  
Resonant Excitation ◽  
Design Parameters ◽  
Blade Vibration ◽  
Baseline Design ◽  
Housing Design ◽  
Radial Turbine ◽  
Turbine Housing ◽  
Generalized Force

Turbocharger turbine blades are subjected to resonant excitation that can lead to High Cycle Fatigue (HCF). In vaneless turbines the excitation primarily stems from asymmetries in the turbine housing such as the volute and the tongue. Given the nature of such asymmetries, the excitation is of a Low Engine Order (LEO) type. The present study deals with the effect of radial turbine housing design on LEO resonant excitation of turbine blades. The study focuses on two geometrical key design parameters of a twin-scroll turbine housing for a radial turbine which is the rotor-tongue distance and the circumferential angle between both tongues. The generalized force approach is used to identify the critical blade surface regions in order to understand the excitation mechanism of each specific design and to assess the differences of design variants with respect to the baseline design. The presented approach is highly practicable, because it is less expensive than full FSI-simulations. This approach is validated on tip timing test data from full-scale experiments. Correlation to test data shows that the presented approach is capable of capturing the relative trends reliably and hence can efficiently be employed in an industrial design process such as to minimize blade vibration amplitudes. It is shown that a reduction of blade vibration amplitudes by a factor of 10 could be achieved.

scholarly journals Development of a Thermal and Structural Analysis Procedure for Cooled Radial Turbines

1988 ◽  
Author(s):  
Ganesh N. Kumar ◽  
Russell G. Deanna
Keyword(s):  
Heat Transfer ◽  
Boundary Conditions ◽  
Three Dimensional ◽  
Internal Flow ◽  
Stream Velocity ◽  
Internal Cooling ◽  
Nasa Lewis Research ◽  
Transfer Coefficients ◽  
Cooling Flow ◽  
Radial Turbine

A procedure for computing the rotor temperature and stress distributions in a cooled radial turbine is considered. Existing codes for modeling the external mainstream flow and the internal cooling flow are used to compute boundary conditions for the heat transfer and stress analyses. An inviscid, quasi three-dimensional code computes the external free stream velocity. The external velocity is then used in a boundary layer analysis to compute the external heat transfer coefficients. Coolant temperatures are computed by a viscous one-dimensional internal flow code for the momentum and energy equation. These boundary conditions are input to a three-dimensional heat conduction code for calculation of rotor temperatures. The rotor stress distribution may be determined for the given thermal, pressure and centrifugal loading. The procedure is applied to a cooled radial turbine which will be tested at the NASA Lewis Research Center. Representative results from this case are included.

Analysis of the Dynamic Response Characteristics of a Flow Meter for Measurement of Pulsating Flow of Liquids

1970 ◽  
Vol 3 (9) ◽  
pp. T155-T156 ◽  
Author(s):  
F. G. Young
Keyword(s):  
Equations Of Motion ◽  
Linear Equations ◽  
Pulsating Flow ◽  
Flow Meter ◽  
Transient Behaviour ◽  
Response Characteristics ◽  
Rapid Flow ◽  
Linear Equations Of Motion ◽  
The University ◽  
Non Linear Equations

An account of the design and development of a prototype flow meter for measuring the flow of liquids under transient conditions was presented by the author at the Symposium on the Measurement of Pulsating Flow at the University of Surrey, April 1970. The flow meter exhibited good transient behaviour in response to rapid flow variations and a favourable correlation existed between theoretically predicted and experimental steady flow results. This paper gives a derivation of the theory underlying the transient behaviour of the instrument and shows how the essentially non-linear equations of motion may be linearised to produce easily manageable linear equations. The good transient response characteristics are accounted for by virtue of the high value of ‘hydraulic stiffness’.

Dynamic Analysis of a Recuperated mGT Cycle for Fuel Cell Hybrid Systems

2016 ◽  
Author(s):  
Luca Larosa ◽  
Alberto Traverso ◽  
Aristide F. Massardo
Keyword(s):  
Fuel Cell ◽  
Dynamic Behaviour ◽  
Simulation Tool ◽  
Performance Gap ◽  
Warm Up ◽  
Transient Phenomena ◽  
Transient Behaviour ◽  
Micro Gas Turbine ◽  
Experimental Campaign ◽  
Start Up

This work presents the dynamic behaviour of a new recuperated micro gas turbine (mGT) coupled with a large volume. Such system, called “emulator”, has been purposely designed for the future upgrade into a fuel cell mGT hybrid system. The tests, carried out by LG Fuel Cell Systems (LGFCS), aimed both at understanding the dynamic behaviour of the system and validating the dynamic simulation tool. Within the wide experimental campaign, a subset of data has been selected to identify the key transient phenomena and characterise the dynamic behaviour of the system: in this respect, the focus is on start-up, warm-up and shutdown phases. A dynamic model of the emulator was developed, based on the original software TRANSEO. The model was used to characterise the mGT performance and identify a performance gap in the expander. For this purpose, the machine was upgraded and substituted. Final results show that, after refinement of input data, the model is capable to predict accurately the overall system transient behaviour.

Dynamic behaviour of automotive catalytic converters subjected to variations in engine exhaust compositions

2005 ◽  
Vol 6 (6) ◽  
pp. 557-567 ◽  
Author(s):  
T Shamim
Keyword(s):  
Dynamic Behaviour ◽  
Single Channel ◽  
Catalytic Converter ◽  
Computational Investigation ◽  
Engine Exhaust ◽  
One Dimensional ◽  
Transient Behaviour ◽  
Fundamental Understanding ◽  
Automotive Catalytic Converters ◽  
Harmful Effects

This paper presents a computational investigation of the effect of composition modulations on an automotive catalytic converter. The objective is to develop a better fundamental understanding of the converte's performance under actual driving conditions. Such an understanding will be beneficial in devising improved emission control methodologies by exploiting the catalyst transient behaviour. The study employs a single-channel-based, one-dimensional, non-adiabatic model. Two types of imposed transients (sinusoidal and step changes) are considered. The results show that composition modulations cause a significant departure in the catalyst behaviour from its steady behaviour, and modulations have both favourable and harmful effects on pollutant conversion.

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