PHASE SHIFT METHODOLOGY ASSESSMENT OF AN AUTOMOTIVE MIXED FLOW TURBOCHARGER TURBINE UNDER PULSATING FLOW CONDITIONS

2015 ◽  
Vol 77 (8) ◽  
Author(s):  
M. H. Padzillah ◽  
S. Rajoo ◽  
R. F. Martinez-Botas
Keyword(s):  
Phase Shift ◽  
Flow Velocity ◽  
Combustion Engine ◽  
Bulk Flow ◽  
Phase Shifting ◽  
Power Matching ◽  
Cfd Models ◽  
Turbine Efficiency ◽  
Turbine Performance ◽  
Computational Fluid Dynamics Cfd

The reciprocating nature of an Internal Combustion Engine (ICE) inevitably results in unsteady flow in the exhaust manifold. In a turbocharged engine, it means that the turbine is subjected to highly pulsating flows at its inlet. The finite time taken by the travelling pressure waves necessitates the need for phase-shifting method before any instantaneous parameter can be analyzed. In a turbocharger test-rig where the instantaneous isentropic power is evaluated upstream of the instantaneous actual power, one of the parameter has to be time-shifted in order to obtain meaningful instantaneous turbine efficiency. This research aims to compare two different methods of phase shifting which are by peak power matching and summation of sonic and bulk flow velocity. In achieving this aim, Computational Fluid Dynamics (CFD) models of full stage turbine operating at 20 Hz, 40 Hz, 60 Hz and 80 Hz have been developed and validated. Instantaneous efficiency was calculated at different locations and the order of calculated efficiency throughout the pulse is analyzed. Results have shown that phase shift using summation of sonic and bulk flow velocity indicated more reasonable efficiency values, thus the method could be used with high confidence for analysis involving unsteady turbine performance.

scholarly journals Optimization of Radial Impulse Turbine for Oscillating Water Column Wave Renewable Energy

2019 ◽  
Vol 8 (12) ◽  
pp. 5699-5703
Keyword(s):  
Water Column ◽  
Oscillating Water Column ◽  
Peak Efficiency ◽  
Impulse Turbine ◽  
Trapped Air ◽  
Turbine Efficiency ◽  
Turbine Performance ◽  
Radial Turbine ◽  
Wide Range ◽  
Computational Fluid Dynamics Cfd

An oscillating water column (OWC) extracts the power of waves by trapping air above a water column. This trapped air is compressed and decompressed by the wave action flow inside a turbine power to the mechanical power during process, and it is important as the turbines are expected to operate in oscillating and reversing flows over a wide range of conditions. The objectives of this study are to determine and analyze the type of radial impulse turbine of OWC and to optimize the performance of a radial impulse turbine for OWC by using Computational Fluid Dynamics (CFD). This requires a comprehensive investigation on turbine configuration, turbine efficiency, OWC integration, and turbine operation with respect to climate condition. The outcome of this study to settle the main drawbacks of radial turbine namely lower peak efficiency and damping on OWC can be considered. Later, these problems will be further study to identify the behavior of the airflow through the machine, sources of energy loss, and impact of different parameters on the turbine performance.

Out With the Old, in With the New: Pelton Hydro Turbine Performance Influence Utilizing Three Different Injector Geometries

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
S. Petley ◽  
A. Židonis ◽  
A. Panagiotopoulos ◽  
D. Benzon ◽  
G. A. Aggidis ◽  
...  
Keyword(s):  
Experimental Testing ◽  
Cfd Analysis ◽  
The Public ◽  
Hydro Turbine ◽  
Turbine Efficiency ◽  
Industry Standard ◽  
Turbine Performance ◽  
Upper Limit ◽  
Computational Fluid Dynamics Cfd ◽  
The Impact

In previous works, the authors presented computational fluid dynamics (CFD) results, which showed that injectors with noticeably steeper nozzle and needle tip angles 110 deg & 70 deg and 150 deg & 90 deg, respectively, attain higher efficiency than the industry standard, which, according to available literature on the public domain, ranges from 80 deg to 90 deg for nozzle and 50–60 deg for needle tip angles. Moreover, experimental testing of the entire Pelton system showed that gains of about 1% in efficiency can be achieved; however there appears to be an upper limit beyond which steeper designs are no longer optimal. This study aims at providing further insight by presenting additional CFD analysis of the runner, which has been coupled with the jet profile from the aforementioned injectors. The results are compared by examining the impact the jet shape has on the runner torque profile during the bucket cycle and the influence this has on turbine efficiency. It can be concluded that the secondary velocities, which contribute to the development of more significant free-surface degradations as the nozzle and needle tip angles are increased, result in a nonoptimal jet runner interaction.

Small scale model for CFD validation in DAF application

2001 ◽  
Vol 43 (8) ◽  
pp. 167-173 ◽  
Author(s):  
J. Hague ◽  
C. T. Ta ◽  
M. J. Biggs ◽  
J. A. Sattary
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Velocity ◽  
Single Phase ◽  
Measured Data ◽  
Phase System ◽  
Two Phase ◽  
Measured Velocity ◽  
Cfd Models ◽  
Computational Fluid Dynamics Cfd

A laboratory model is used to measure the generic flow patterns in dissolved air flotation (DAF). The Perspex model used in this study allows the use of laser Doppler velocimetry (LDV), a non-invasive, high-resolution (±2 mm s−1) laser technique of flow velocity measurement. Measurement of flow velocity in the single-phase situation was first carried out. Air-saturated water was then supplied to the tank and measurements of bubble velocity in the two-phase system were made. Vertical flow re-circulation was observed in the flotation zone. In the bottom of the flotation zone (near the riser) secondary flow re-circulation was observed, but only in the two-phase system. Another phenomenon was the apparent movement of flow across the tank width, which may be due to lateral dispersion of the bubble cloud. Data from preliminary computational fluid dynamics (CFD) models were compared against this measured data in the case of the single-phase system. The CFD model incorporating a k-e model of turbulence was found to give closer agreement with the measured data than the corresponding laminar flow model. The measured velocity data will be used to verify two-phase computational fluid dynamics (CFD) models of DAF.

Modeling of Compressor Drum Cavities With Radial Inflow

2016 ◽  
Author(s):  
D. Amirante ◽  
Z. Sun ◽  
J. W. Chew ◽  
N. J. Hills ◽  
N. R. Atkins
Keyword(s):  
Thermal Stratification ◽  
Turbulence Modeling ◽  
Navier Stokes ◽  
Inflow Rate ◽  
Cfd Models ◽  
Flow And Heat Transfer ◽  
Rotating Discs ◽  
Computational Fluid Dynamics Cfd ◽  
Inlet Conditions ◽  
Cooling Air

Reynolds-Averaged Navier-Stokes (RANS) computations have been conducted to investigate the flow and heat transfer between two co-rotating discs with an axial throughflow of cooling air and a radial bleed introduced from the shroud. The computational fluid dynamics (CFD) models have been coupled with a thermal model of the test rig, and the predicted metal temperature compared with the thermocouple data. CFD solutions are shown to vary from a buoyancy driven regime to a forced convection regime, depending on the radial inflow rate prescribed at the shroud. At a high radial inflow rate, the computations show an excellent agreement with the measured temperatures through a transient rig condition. At a low radial inflow rate, the cavity flow is destabilized by the thermal stratification. Good qualitative agreement with the measurements is shown, although a significant over-prediction of disc temperatures is observed. This is associated with under prediction of the penetration of the axial throughflow into the cavity. The mismatch could be the result of strong sensitivity to the prescribed inlet conditions, in addition to possible shortcomings in the turbulence modeling.

scholarly journals Measurement of flow velocity profiles in tank structures using the prototype device OCM Pro LR

2011 ◽  
Vol 64 (1) ◽  
pp. 263-270 ◽  
Author(s):  
K. Klepiszewski ◽  
M. Teufel ◽  
S. Seiffert ◽  
E. Henry
Keyword(s):  
Flow Velocity ◽  
Large Scale ◽  
Fluid Dynamic ◽  
Waste Water Treatment ◽  
Transport Processes ◽  
Treatment Efficiency ◽  
Cleaning Efficiency ◽  
Cfd Modelling ◽  
Ultrasonic Signals ◽  
Cfd Models

Generally, studies investigating the treatment efficiency of tank structures for storm water or waste water treatment observe pollutant flows in connection with conditions of hydraulic loading. Further investigations evaluate internal processes in tank structures using computational fluid dynamic (CFD) modelling or lab scale tests. As flow paths inside of tank structures have a considerable influence on the treatment efficiency, flow velocity profile (FVP) measurements can provide a possibility to calibrate CFD models and contribute to a better understanding of pollutant transport processes in these structures. This study focuses on tests carried out with the prototype FVP measurement device OCM Pro LR by NIVUS in a sedimentation tank with combined sewer overflow (CSO) situated in Petange, Luxembourg. The OCM Pro LR measurement system analyses the echo of ultrasonic signals of different flow depths to get a detailed FVP. A comparison of flow velocity measured by OCM Pro LR with a vane measurement showed good conformity. The FVPs measured by OCM Pro LR point out shortcut flows within the tank structure during CSO events, which could cause a reduction of the cleaning efficiency of the structure. The results prove the applicability of FVP measurements in large-scale structures.

The Effect of Bench Arrangements on the Natural Ventilation of a Multispan Greenhouse

2013 ◽  
Author(s):  
Sunita Kruger ◽  
Leon Pretorius
Keyword(s):  
Fluid Dynamics ◽  
Natural Ventilation ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Low Velocity ◽  
Lower Velocity ◽  
Cfd Models ◽  
Temperature Distributions ◽  
Computational Fluid Dynamics Cfd ◽  
Plant Level

In this paper, the influence of various bench arrangements on the microclimate inside a two-span greenhouse is numerically investigated using three-dimensional Computational Fluid Dynamics (CFD) models. Longitudinal and peninsular arrangements are investigated for both leeward and windward opened roof ventilators. The velocity and temperature distributions at plant level (1m) were of particular interest. The research in this paper is an extension of two-dimensional work conducted previously [1]. Results indicate that bench layouts inside the greenhouse have a significant effect on the microclimate at plant level. It was found that vent opening direction (leeward or windward) influences the velocity and temperature distributions at plant level noticeably. Results also indicated that in general, the leeward facing greenhouses containing either type of bench arrangement exhibit a lower velocity distribution at plant level compared to windward facing greenhouses. The latter type of greenhouses has regions with relatively high velocities at plant level which could cause some concern. The scalar plots indicate that more stagnant areas of low velocity appear for the leeward facing greenhouses. The windward facing greenhouses also display more heterogeneity at plant level as far as temperature is concerned.

Joint Estimation of Bulk Flow Velocity and Angle Using a Lateral Line Probe

2016 ◽  
Vol 65 (3) ◽  
pp. 601-613 ◽  
Author(s):  
Nataliya Strokina ◽  
Joni-Kristian Kamarainen ◽  
Jeffrey A. Tuhtan ◽  
Juan Francisco Fuentes-Perez ◽  
Maarja Kruusmaa
Keyword(s):  
Flow Velocity ◽  
Lateral Line ◽  
Joint Estimation ◽  
Bulk Flow

Correcting Turbocharger Performance Measurements for Heat Transfer and Friction

2017 ◽  
Author(s):  
Mario Schinnerl ◽  
Jan Ehrhard ◽  
Mathias Bogner ◽  
Joerg Seume
Keyword(s):  
Heat Transfer ◽  
Combustion Engine ◽  
Measurement Data ◽  
Internal Heat ◽  
Friction Model ◽  
Heat Transfer Model ◽  
Transfer Model ◽  
Friction Power ◽  
Turbine Efficiency ◽  
Compressor Efficiency

The measured performance maps of turbochargers which are commonly used for the matching process with a combustion engine are influenced by heat transfer and friction phenomena. Internal heat transfer from the hot turbine side to the colder compressor side leads to an apparently lower compressor efficiency at low to mid speeds and is not comparable to the compressor efficiency measured under adiabatic conditions. The product of the isentropic turbine efficiency and the mechanical efficiency is typically applied to characterize the turbine efficiency and results from the power balance of the turbocharger. This so-called ‘thermo-mechanical’ turbine efficiency is strongly correlated with the compressor efficiency obtained from measured data. Based on a previously developed one-dimensional heat transfer model, non-dimensional analysis was carried out and a generally valid heat transfer model for the compressor side of different turbochargers was developed. From measurements and ramp-up simulations of turbocharger friction power, an analytical friction power model was developed to correct the thermo-mechanical turbine efficiency from friction impact. The developed heat transfer and friction model demonstrates the capability to properly predict the adiabatic (aerodynamic) compressor and turbine performance from measurement data obtained at a steady-flow hot gas test bench.

Impact of Severe Temperature Distortion on Turbine Efficiency

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
Paul F. Beard ◽  
Andy Smith ◽  
Thomas Povey
Keyword(s):  
Computational Study ◽  
Measurement Techniques ◽  
Inlet Temperature ◽  
Turbine Efficiency ◽  
Computational Fluid Dynamics Cfd ◽  
External Flows ◽  
Torque Transducer ◽  
Formed Part ◽  
Low Uncertainty ◽  
The Eu

This paper presents an experimental and computational study of the effect of severe inlet temperature distortion (hot streaks) on the efficiency of the MT1 HP turbine, which is a highly-loaded unshrouded transonic design. The experiments were performed in the Oxford Turbine Research Facility (OTRF) (formerly the TTF at QinetiQ Farnborough): an engine scale, short duration, rotating transonic facility, in which M, Re, Tgas/Twall and N/T01 are matched to engine conditions. The research formed part of the EU Turbine Aero-Thermal External Flows (TATEF II) program. An advanced second generation temperature distortion simulator was developed for this investigation, which allows both radial and circumferential temperature profiles to be simulated. A pronounced profile was used for this study. The system was novel in that it was designed to be compatible with an efficiency measurement system which was also developed for this study. To achieve low uncertainty (bias and precision errors of approximately 1.5% and 0.2% respectively, to 95% confidence), the mass flow rate of the hot and cold streams used to simulate temperature distortion were independently metered upstream of the turbine nozzle using traceable measurement techniques. Turbine power was measured directly with an accurate torque transducer. The efficiency of the test turbine was evaluated experimentally for a uniform inlet temperature condition, and with pronounced temperature distortion. Mechanisms for observed changes in the turbine exit flow field and efficiency are discussed. The data are compared in terms of flow structure to full stage computational fluid dynamics (CFD) performed using the Rolls Royce Hydra code.

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