scholarly journals One-dimensional modeling of the interaction between close-coupled injection events for a ballistic solenoid injector

2018 ◽  
Vol 20 (4) ◽  
pp. 452-469 ◽  
Author(s):  
Raul Payri ◽  
Joaquin De la Morena ◽  
Vincenzo Pagano ◽  
Ali Hussain ◽  
Gilbert Sammut ◽  
...  
Keyword(s):  
Dwell Time ◽  
Dynamic Pressure ◽  
Injection Pressure ◽  
Operating Conditions ◽  
One Dimensional ◽  
Dimensional Modeling ◽  
Custom Made ◽  
Wide Range ◽  
Common Rail Injector ◽  
Injection Strategies

In this article, an investigation of a solenoid common-rail injector has been carried out to understand the hydraulic interactions between close-coupled injection events. For this purpose, a one-dimensional model of the injector was developed on GT-SUITE software. The geometrical and hydraulic characteristics of the internal elements of the injector, needed to construct the model, were obtained by means of different custom-made experimental tools. The dynamic behavior of the injector was characterized using an EVI rate of injection meter. The hydraulic results from the model show a good alignment with the experiments for single injections and a varied degree of success for multiple injections. Once the model was validated, it has been used to understand the injector performance under multiple-injection strategies. The mass of a second injection has shown to highly depend on the electrical dwell time, especially at low values, mostly due to the dynamic pressure behavior in the needle seat. The critical dwell time, defined as the minimum electrical dwell time needed to obtain two independent injection events, has been numerically obtained on a wide range of operating conditions and correlated to injection pressure and energizing time of the first injection. Finally, the increase in the needle opening velocity of the second injection compared to the single-injection case has been analyzed for close-coupled injection events.

A predictive combustion model for one-dimensional gasoline engine simulation

2020 ◽  
pp. 146808742094590
Author(s):  
Yoshihiro Nomura ◽  
Seiji Yamamoto ◽  
Makoto Nagaoka ◽  
Stephan Diel ◽  
Kenta Kurihara ◽  
...  
Keyword(s):  
Gasoline Engine ◽  
Early Stage ◽  
Burning Velocity ◽  
Turbulent Flame ◽  
Operating Conditions ◽  
Combustion Model ◽  
One Dimensional ◽  
Turbulent Reynolds Number ◽  
Proposed Model ◽  
Wide Range

A new predictive combustion model for a one-dimensional computational fluid dynamics tool in the multibody dynamics processes of gasoline engines was developed and validated. The model consists of (1) a turbulent burning velocity model featuring a flame radius–based transitional function, steady burning velocity that considers local quenching using the Karlovitz number and laminarization by turbulent Reynolds number, as well as turbulent flame thickness and its quenching model near the liner wall, and (2) a knock model featuring auto-ignition by the Livengood–Wu integration and ignition delay time obtained using a full-kinetic model. The proposed model and previous models were verified under a wide range of operating conditions using engines with widely different specifications. Good agreement was only obtained for combustion characteristics by the proposed model without requiring individual calibration of model constants. The model was also evaluated for utilization after prototyping. Improved accuracy, especially of ignition timing, was obtained after further calibration using a small amount of engine data. It was confirmed that the proposed model is highly accurate at the early stage of the engine development process, and is also applicable for engine calibration models that require higher accuracy.

Analysis of Gas Turbine Rotating Cavities by an One-Dimensional Model

2009 ◽  
Author(s):  
Riccardo Da Soghe ◽  
Bruno Facchini ◽  
Luca Innocenti ◽  
Mirko Micio
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Design Tool ◽  
Operating Conditions ◽  
Outer Flow ◽  
One Dimensional ◽  
Wide Range ◽  
Air System ◽  
Secondary Air ◽  
Radial Outflow

Reliable design of secondary air system is one of the main tasks for the safety, unfailing and performance of gas turbine engines. To meet the increasing demands of gas turbines design, improved tools in prediction of the secondary air system behavior over a wide range of operating conditions are needed. A real gas turbine secondary air system includes several components, therefore its analysis is not carried out through a complete CFD approach. Usually, that predictions are performed using codes, based on simplified approach which allows to evaluate the flow characteristics in each branch of the air system requiring very poor computational resources and few calculation time. Generally the available simplified commercial packages allow to correctly solve only some of the components of a real air system and often the elements with a more complex flow structure cannot be studied; among such elements, the analysis of rotating cavities is very hard. This paper deals with a design-tool developed at the University of Florence for the simulation of rotating cavities. This simplified in-house code solves the governing equations for steady one-dimensional axysimmetric flow using experimental correlations both to incorporate flow phenomena caused by multidimensional effects, like heat transfer and flow field losses, and to evaluate the circumferential component of velocity. Although this calculation approach does not enable a correct modeling of the turbulent flow within a wheel space cavity, the authors tried to create an accurate model taking into account the effects of inner and outer flow extraction, rotor and stator drag, leakages, injection momentum and, finally, the shroud/rim seal effects on cavity ingestion. The simplified calculation tool was designed to simulate the flow in a rotating cavity with radial outflow both with a Batchelor and/or Stewartson flow structures. A primary 1D-code testing campaign is available in the literature [1]. In the present paper the authors develop, using CFD tools, reliable correlations for both stator and rotor friction coefficients and provide a full 1D-code validation comparing, due to lack of experimental data, the in house design-code predictions with those evaluated by CFD.

Predicted Effects of Bearing Sump and Injection Pressures on Oil Labyrinth Leakage

2002 ◽  
Vol 125 (1) ◽  
pp. 316-325 ◽  
Author(s):  
S.-Y. Park ◽  
D. L. Rhode
Keyword(s):  
Injection Pressure ◽  
Computer Code ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Vapor Flow ◽  
Buffer Gas ◽  
Labyrinth Seals ◽  
Process Gas ◽  
New Information ◽  
Wide Range

New information and an enhanced understanding concerning the oil vapor contaminant leaking through nonflooded oil labyrinth seals are provided. The results were obtained using a finite volume Navier-Stokes computer code that was extended to include the concentration transport equation. The minimum (i.e., critical) pressure and flow rate at which uncontaminated buffer gas must be injected to prevent oil vapor from leaking to the process gas was determined for a range of seal geometries and operating conditions. It was found that the variation of the critical buffer-gas injection pressure with bearing gas and process gas pressures, for example, was surprisingly small for the cases considered. In addition, the bearing gas and oil vapor flow rates for a wide range of bearing and injection (where present) pressures and geometries were determined for both buffered as well as nonbuffered seals.

scholarly journals Development and validation of a reduced mechanism for methane using a new integral algorithm in a premixed flame

2014 ◽  
Vol 68 (5) ◽  
pp. 529-539
Author(s):  
Zuozhu Wu ◽  
Xinqi Qiao ◽  
Zhen Huang
Keyword(s):  
Reduction Process ◽  
Operating Conditions ◽  
Computational Domain ◽  
Fast Reaction ◽  
One Dimensional ◽  
Reduced Mechanism ◽  
Wide Range ◽  
Computational Singular Perturbation ◽  
Premixed Laminar ◽  
Development And Validation

A new algorithm based on Computational Singular Perturbation (CSP) is proposed to construct global reduced mechanism. The algorithm introduces species concentrations, species net production rates and heat release rates as integral weighting factors to integrate CSP-pointers, including radical pointers and fast reaction pointers, throughout the computational domain. A software package based on the algorithm was developed to make the reduction process more efficient. Input to the algorithm includes (i) the detailed mechanism, (ii) the numerical solution of the problem for a specific set of operating conditions, (iii) the number of quasi steady state (QSS) species. The proposed algorithm was applied to the reduction of GRI3.0 involving 53 species and 325 reactions leading to the development of a 15-species reduced mechanism with 10 lumped steps. Then the reduced mechanism was validated in a one-dimensional, unstretched, premixed, laminar steady flame over a wide range of equivalence ratio, and excellent agreements between results calculated with the detailed and the reduced mechanisms can be observed.

scholarly journals Identification of a Material–Lubricant Pairing and Operating Conditions That Lead to the Failure of Porous Journal Bearing Systems

2020 ◽  
Vol 68 (4) ◽  
Author(s):  
Guido Boidi ◽  
Stefan Krenn ◽  
Stefan J. Eder
Keyword(s):  
Mixed Lubrication ◽  
Operating Conditions ◽  
Maximum Temperature ◽  
Asperity Contact ◽  
Operational Conditions ◽  
Practical Applications ◽  
Custom Made ◽  
Wide Range ◽  
Lab Test ◽  
Wear Tests

AbstractIn this study, we perform accelerated wear tests with porous journal bearings (PJBs) on a lab test rig, providing statistically reliable results under realistic operational conditions. To this end, a custom-made tribometer consisting of 5 mechanically independent but centrally controlled units was used to test five identical bearings in parallel. The test parameters were tuned to promote enough wear under mixed lubrication by increasing the clearance gap and the radial load, while minimizing the bidirectional rotational speed. A wide range of lubricant and material combinations were evaluated, the vast majority of which performed excellently (i.e., negligible wear and low friction). Only one notable combination of a low-density iron bearing paired with a standard PAO-based lubricant failed when operating at low rotational speeds, exhibiting highly unstable frictional behavior and 10–20 times the typical wear in practical applications. An analysis of Stribeck curves, recorded periodically during the wear tests as a diagnostic tool, proved that this particular combination of materials and parameters failed to run in properly, with deteriorating tribological behavior over time. A direct relation between the total wear and the maximum temperature in the tribocontact during testing helped identify this pairing as the only one operating solely under mixed lubrication (high asperity contact), explaining the excessive wear. Graphical Abstract

scholarly journals Unsteady Flow Characteristics in a Centrifugal Compressor With Vaned Diffuser

1987 ◽  
Author(s):  
A. N. Abdel-Hamid ◽  
U. Haupt ◽  
M. Rautenberg
Keyword(s):  
Centrifugal Compressor ◽  
High Performance ◽  
Dynamic Pressure ◽  
Flow Characteristics ◽  
Rotating Stall ◽  
Operating Conditions ◽  
Impeller Speed ◽  
Vaned Diffuser ◽  
Wide Range ◽  
Flow Oscillations

Self-excited flow oscillations in a high performance centrifugal compressor with vaned diffuser have been experimentally investigated over a wide range of operating conditions. The space and time characteristics of the flow oscillations in the compressor from inlet to outlet were measured using fast response dynamic pressure transducers on the shroud wall and blade mounted straingages. Multi-channel signal analysis techniques in the frequency domain clearly identified the onset of the oscillations and its type. Rotating stall was found to exist in certain regimes of the compressor map but did not necessarily preceed the occurrence of the surge phenomena. At compressor speeds below 13600 rpm the rotating non-uniform flow when it occurred was composed of three lobes and rotated at approximately 5–6 % of the impeller speed. Above 13600 rpm the rotating pattern changed to two lobes and rotated at approximately 16–20 % of the impeller speed. The direction of rotation of both patterns was opposite to that of the impeller. Analysis of the performance characteristics of the compressor components prior to and during flow oscillations indicates that the relative magnitude of the flow fluctuations in the semi-vaneless space downstream of the impeller are the largest which points towards the close relationship between the conditions leading to the onset of the oscillations and the flow details in this region of the compressor. Additional confirmation of this relationship is obtained from comparison between the results obtained in this study and those obtained when the same compressor was operated with a vaneless diffuser.

scholarly journals Hydraulic Interactions between Injection Events Using Multiple Injection Strategies and a Solenoid Diesel Injector

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3087
Author(s):  
Simón Martínez-Martínez ◽  
Oscar A. de la Garza ◽  
Miguel García-Yera ◽  
Ricardo Martínez-Carrillo ◽  
Fausto A. Sánchez-Cruz
Keyword(s):  
Dwell Time ◽  
Injection Rate ◽  
Operating Conditions ◽  
Multiple Injection ◽  
Rail Pressure ◽  
Injection Strategy ◽  
Fuel Mass ◽  
And Control ◽  
Injection Strategies ◽  
Do So

An experimental study was performed to explore the influence of dwell time on the hydraulic interactions between injection events using pilot injection strategy, split injection strategy, post injection strategy and a solenoid diesel injector. To do so, a sweep of dwell time from 0.55 up to 2 ms using all multiple injection strategies and levels of rail pressure, of 80, 100 and 120 MPa, and single level of back pressure, of 5 MPa, was performed. The hydraulic interactions between injection events were characterized through the second injection hydraulic delay and second injection mass in an injection discharge curve indicator equipped with all the components required for its operation and control. In order to define the operating conditions of the multiple injection strategies, to ensure the same injected fuel mass in all cases, the characteristic curves of injection rate for the solenoid diesel injector studied were obtained. The second injection hydraulic delay increases with dwell time values in the range of 0.55–0.9 ms for all multiple injection strategies and levels of rail pressure tested. Conversely, the second injection hydraulic delay decreases with dwell time values higher than 0.9 ms. Moreover, the second hydraulic delay depends mainly on the dwell time and not on the injected fuel mass during the first injection event. The second injection mass increases with dwell values less than 0.6 ms. By contrast, the second injection mass is not significantly affected by that of the first injection at a dwell time higher than 0.6 ms.

Effects of Nozzle Hole Arrangement on Diesel Engine Emissions

2009 ◽  
Author(s):  
Prashanth K. Karra ◽  
Song-Charng Kong
Keyword(s):  
Injection Pressure ◽  
Exhaust Gas Recirculation ◽  
Operating Conditions ◽  
Exhaust Gas ◽  
Low Temperature Combustion ◽  
Convergent Nozzle ◽  
Wide Range ◽  
Soot Emissions ◽  
Gas Recirculation ◽  
Injection Pressures

Various diesel injectors and injection pressures were tested along with exhaust gas recirculation to achieve low NOx and soot emissions. The injectors used in the study included a 6-hole nozzle, a 10-hole nozzle, and a 6-hole convergent nozzle with a K-factor of 3. All three injectors had the same flow numbers and they were effective in reducing NOx and soot emissions at appropriate conditions. It was found that low temperature combustion can be achieved by using high levels of exhaust gas recirculation with late injection timings. High injection pressures significantly reduced soot emissions at conventional injection timings. The effect of injection pressure was not significant at retarded injection timings, i.e., 5 ATDC. The convergent nozzle was found to produce higher soot emissions and its effects on NOx emissions and fuel consumption were not significant. The small nozzle size in the 10-hole injector can generate smaller fuel drops and lead to better atomization. The 10-hole injector appeared to have better air utilization and resulted in significant reductions in NOx and soot emissions over a wide range of operating conditions.

CFD Modeling of Pilot Injection and EGR in DI Diesel Engines

2004 ◽  
Author(s):  
Arturo de Risi ◽  
Teresa Donateo ◽  
Domenico Laforgia
Keyword(s):  
Shell Model ◽  
Diesel Engines ◽  
Direct Injection ◽  
Operating Conditions ◽  
Spray Angle ◽  
Cfd Modeling ◽  
Pilot Injection ◽  
Wide Range ◽  
Combustion Processes ◽  
Injection Strategies

The simulation of direct injection diesel engines requires accurate models to predict spray evolution and combustion processes. Several models have been proposed and widely tested for traditional injection strategies characterized by single injection pulse close to top dead center. Unfortunately, these models show some limits when applied to different injection strategies so that a correct simulation of engine performances and emission cannot be achieved without changing variables included in spray and combustion models. The aim of the present investigation is to improve the prediction capability of the KIVA3V code in case of pilot injection in order to use numerical simulations to define optimized pilot injection strategies. This goal was achieved by eliminating the hypotheses of constant fuel density and constant spray angle in the KIVA3V code and by using a modified version of the Shell model. The proposed modifications to the Shell model allow a better description of low temperature kinetics by the addition of two more radicals and three new kinetics reactions. The improvements in the code were verified by comparing experimental data and numerical results over a wide range of operating conditions including single injections, pilot injections and EGR.

Analysis of Gas Turbine Rotating Cavities by a One-Dimensional Model: Definition of New Disk Friction Coefficient Correlations Set

2010 ◽  
Vol 133 (2) ◽  
Author(s):  
Riccardo Da Soghe ◽  
Bruno Facchini ◽  
Luca Innocenti ◽  
Mirko Micio
Keyword(s):  
Gas Turbine ◽  
Axisymmetric Flow ◽  
Operating Conditions ◽  
Dimensional Model ◽  
Outer Flow ◽  
One Dimensional ◽  
Wide Range ◽  
Air System ◽  
Secondary Air ◽  
Radial Outflow

Reliable design of a secondary air system is one of the main tasks for the safety and unfailing performance of gas turbine engines. To meet the increasing demands of gas turbine designs, improved tools in the prediction of secondary air system behavior over a wide range of operating conditions are needed. A real gas turbine secondary air system includes several components, therefore, its analysis is not carried out through a complete computational fluid dynamics (CFD) approach. Usually, those predictions are performed using codes based on simplified approach, which allows to evaluate the flow characteristics in each branch of the air system requiring very poor computational resources and few calculation time. Generally, the available simplified commercial packages allow to correctly solve only some of the components of a real air system, and often, the elements with a more complex flow structure cannot be studied; among such elements, the analysis of rotating cavities is very hard. This paper deals with a design tool developed at the University of Florence for the simulation of rotating cavities. This simplified in-house code solves the governing equations for steady one-dimensional axisymmetric flow using experimental correlations, both to incorporate the flow phenomena caused by multidimensional effects such as heat transfer and flow field losses, and to evaluate the circumferential component of velocity. Although this calculation approach does not enable a correct modeling of the turbulent flow within a wheel space cavity, the authors tried to create an accurate model, taking into account the effects of inner and outer flow extraction, rotor and stator drag, leakages, injection momentum, and finally, the shroud/rim seal effects on cavity ingestion. The simplified calculation tool was designed to simulate the flow in a rotating cavity with radial outflow, both with the Batchelor and/or Stewartson flow structures. A primary 1D-code testing campaign is available in the literature (2008, “Analysis of Gas Turbine Rotating Cavities by a One-Dimensional Model,” ISROMAC Paper No. 12-2008-20161). In the present paper, the authors developed, using CFD tools, reliable correlations for both stator and rotor friction coefficients and provided a full 1D-code validation, due to the lack of experimental data, comparing the in-house design-code predictions with those evaluated by CFD.

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