Numerical Analysis of Swirl Control Strategies in a Four Valve HSDI Diesel Engine

2004 ◽  
Author(s):  
S. Fontanesi ◽  
E. Mattarelli ◽  
L. Montorsi
Keyword(s):  
Flow Field ◽  
Control Strategies ◽  
Cfd Simulations ◽  
Full Load ◽  
Partial Load ◽  
Swirl Intensity ◽  
Port Design ◽  
Current Production ◽  
Hsdi Diesel Engine ◽  
Cylinder Flow

Recent four value HSDI Diesel engines are able to control the swirl intensity, in order to enhance the in-cylinder flow field at partial load without decreasing breathing capabilities at full load. Making reference to a current production engine, the purpose of this paper is to envestiage the influence of port design and flow-control strategies on both engine permeability and in-cylinder flow field. Using previously validated models, 3-D CFD simulations of the intake and compression strokes are performed in order to predict the in-cylinder flow patterns originated by the different configurations. The comparison between the two configurations in terms of airflow at full load indicates that Geometry 2 can trap 3.03% more air than Geometry 1, while the swirl intensity at IVC is reduced (−30%). The closure of one intake valve (the left one) is very effective to enhance the swirl intensity at partial load: the Swirl Ratio at IVC passes from 0.7 to 2.6 for Geometry 1, while for Geometry 2 it varies from 0.4 to 2.9.

Comparison Between Steady and Unsteady CFD Simulations of Two Different Port Designs in a Four Valve HSDI Diesel Engine: Swirl Intensity and Engine Permeability

2004 ◽  
Author(s):  
Giuseppe Cantore ◽  
Stefano Fontanesi ◽  
Luca Montorsi ◽  
Paolo Ortolani
Keyword(s):  
Steady State ◽  
Diesel Engine ◽  
Control Strategies ◽  
Charge Motion ◽  
Cfd Simulations ◽  
Dynamic Simulations ◽  
Induction Process ◽  
Swirl Intensity ◽  
Hsdi Diesel Engine ◽  
Intake Swirl

Swirl control strategies are useful methods for controlling mixture formation in HSDI Diesel engines. Test rigs allows only steady state measurements of the Swirl number, and give only a rough estimation of the charge motion during the actual compression stroke within the engine. On the contrary, CFD simulations are powerful tools to characterize the air flow drawn into the cylinder, since they allow not only steady state operations, but also full dynamic modeling of the intake and compression strokes. This paper studies an application of computational fluid dynamics for predicting intake swirl intensity in an automotive 4 valve per cylinder C.I. Diesel engine. Two different intake ports are compared and the best trade off between engine permeability and swirl intensity is assessed. Both steady state and dynamic simulations of the induction process are carried out, and results demonstrate that steady state analysis is a reliable tool for predicting the port permeability, while the same capability is not proved in investigating the organized charge motion within the chamber.

Flow Field Prediction and Bubble Trajectory Model in Gas-Liquid Cylindrical Cyclone (GLCC) Separators

1999 ◽  
Vol 121 (1) ◽  
pp. 9-14 ◽  
Author(s):  
I. Mantilla ◽  
S. A. Shirazi ◽  
O. Shoham
Keyword(s):  
Flow Field ◽  
Flow Model ◽  
Mechanistic Models ◽  
Cfd Simulations ◽  
Trajectory Model ◽  
Swirl Intensity ◽  
Cylindrical Cyclone ◽  
Fluid Properties ◽  
Inlet Geometry ◽  
Computational Fluid Dynamics Cfd

Several mechanistic models have been already developed for predicting the onset of liquid carryover in gas-liquid cylindrical cyclone (GLCC) separators. However, currently no model is available to predict gas carryunder. A bubble trajectory model has been developed that can be used to determine the initiation of gas carryunder in the GLCC and to design GLCC for field applications. The bubble trajectory model uses a predicted flow field in GLCC that is based on swirl intensity. This paper describes the development of a general correlation to predict the decay of the swirl intensity. The correlation accounts for the effects of fluid properties (Reynolds number) as well as inlet geometry. Available experimental data as well as computational fluid dynamics (CFD) simulations were used to validate the correlation. The swirl intensity is used to calculate the local axial and tangential velocities. The flow model and improved bubble trajectory results agree with experimental observation and CFD results. Examples are provided to show how the bubble trajectory model can be used to design GLCC.

scholarly journals Effect of Engine Specifications on In-Cylinder Flow Field in a Spark-Ignited Natural Gas Engine

1999 ◽  
Vol 34 (11) ◽  
pp. 764-773
Author(s):  
Yukiyoshi Fukano ◽  
Kazuo Tachibana ◽  
Shigeo Kida ◽  
Toshikazu Kadota
Keyword(s):  
Natural Gas ◽  
Flow Field ◽  
Gas Engine ◽  
Natural Gas Engine ◽  
Cylinder Flow

Investigation of Swirl Ratio Impact on In-Cylinder Flow in a SIDI Optical Engine

2015 ◽  
Author(s):  
Hanyang Zhuang ◽  
David L. S. Hung ◽  
Jie Yang ◽  
Shaoxiong Tian
Keyword(s):  
Flow Field ◽  
Soot Formation ◽  
Flow Characteristics ◽  
Control Valve ◽  
Exhaust Emission ◽  
Swirl Ratio ◽  
Optical Engine ◽  
Crank Angle ◽  
Cylinder Flow ◽  
Intake Swirl

Advanced powertrain technologies have improved engine performance with higher power output, lower exhaust emission, and better controllability. Chief among them is the development of spark-ignition direct-injection (SIDI) engines in which the in-cylinder processes control the air flow motion, fuel-air mixture formation, combustion, and soot formation. Specifically, intake air with strong swirl motion is usually introduced to form a directional in-cylinder flow field. This approach improves the mixing process of air and fuel as well as the propagation of flame. In this study, the effect of intake air swirl on in-cylinder flow characteristics was experimentally investigated. High speed particle image velocimetry (PIV) was conducted in an optical SIDI engine to record the flow field on a swirl plane. The intake air swirl motion was achieved by adjusting the opening of a swirl ratio control valve which was installed in one of the two intake ports in the optical engine. Ten opening angles of the swirl ratio control valve were adjusted to produce an intake swirl ratio from 0.55 to 5.68. The flow structures at the same crank angle degree, but under different swirl ratio, were compared and analyzed using proper orthogonal decomposition (POD). The flow dominant structures and variation structures were interpreted by different POD modes. The first POD mode captured the most dominant flow field structure characteristics; the corresponding mode coefficients showed good linearity with the measured swirl ratio at the compression stroke when the flow was swirling and steady. During the intake stroke, strong intake air motion took place, and the structures and coefficients of the first modes varied along different swirl ratio. These modes captured the flow properties affected by the intake swirl motion. Meanwhile, the second and higher modes captured the variation feature of the flow at various crank angle degrees. In summary, this paper demonstrated a promising approach of using POD to interpret the effectiveness of swirl control valve on in-cylinder swirl flow characteristics, providing better understanding for engine intake system design and optimization.

Research on the Design Method of the Centrifugal Pump With Splitter Blades

2009 ◽  
Author(s):  
Shouqi Yuan ◽  
Jinfeng Zhang ◽  
Yue Tang ◽  
Jianping Yuan ◽  
Yuedeng Fu
Keyword(s):  
Flow Field ◽  
Centrifugal Pump ◽  
Design Method ◽  
Flow Distribution ◽  
Orthogonal Test ◽  
Operating Conditions ◽  
Test Results ◽  
Cfd Simulations ◽  
Pump Performance ◽  
Blade Number

The research on a centrifugal pump of low specific speed with splitter blades was carried out in recent years by our group, is systematically introduced in this paper. The design method is summarized also. At the beginning, based on the former L9(34) orthogonal test, Particle Imagine Velocity (PIV) tests and Computational Fluid Dynamics (CFD) simulations were carried out for several designs with different splitter blade length. Results show that for an impeller with splitter blades the “jet-wake” flow at the impeller outlet is improved, and the velocity distribution inside the impeller is more uniform. This explains that the impeller with splitter blades shows higher performance (especially in head and efficiency). Meanwhile, the numerical simulation results were compared with the test results, which confirm that, CFD technology can be used to observe inner flow distribution and forecast pump performance tendency. Later, a further L9(34) orthogonal test, which adopt the blade number as a new variable, was designed to explore the relationship between geometry parameters of splitter blade and pump performance, and corresponding CFD simulations for the flow field with volute were also done. From the test results the influence of the main design parameters on the hydraulic performance of a centrifugal pump and its reasonable value range are determined. The simulations forecasted pump performance show good consistency with that from tests at the rated point, and the simulated error at other flow rates were analyzed. Thirdly, in order to save research cost, numerical simulations were done for the full flow field including the cavity inside the volute and impeller. By analyzing the distribution law of blade torque and turbulent kinetic energy in the impeller, the value fetching principle for the splitter blade inlet diameter is presented as “the splitter blades torque should be positive”, and by analyzing the distribution of blades loading, the flow distribution rules and pump performance influenced by different splitter blades off-setting angles and inlet diameters were discovered. The disk friction loss, which consuming much energy in centrifugal pumps, was also forecasted at various operating conditions. The results were compared with that from empirical formulas, which show great accordance at the rated point, and the forecasted results at off-design points were analyzed also. Finally, the research results and the design method for the centrifugal pump with splitter blades, such as how to select splitter blade number, the off-setting angle, the inlet diameter and the deflection angle, were summarized.

Performance of Francis Turbine Operating at Excess Load Condition

2020 ◽  
Author(s):  
Muhannad Altimemy ◽  
Justin Caspar ◽  
Alparslan Oztekin
Keyword(s):  
Flow Field ◽  
Draft Tube ◽  
Turbine Blades ◽  
Pressure Fluctuations ◽  
Load Condition ◽  
Operating Conditions ◽  
Francis Turbine ◽  
Partial Load ◽  
Dynamics Simulations ◽  
Excess Load

Abstract Computational fluid dynamics simulations are conducted to characterize the spatial and temporal characteristics of the flow field inside a Francis turbine operating in the excess load regime. A high-fidelity Large Eddy Simulation (LES) turbulence model is applied to investigate the flow-induced pressure fluctuations in the draft tube of a Francis Turbine. Probes placed alongside the wall and in the center of the draft tube measure the pressure signal in the draft tube, the pressure over the turbine blades, and the power generated to compare against previous studies featuring design point and partial load operating conditions. The excess load is seen during Francis turbines in order to satisfy a spike in the electrical demand. By characterizing the flow field during these conditions, we can find potential problems with running the turbine at excess load and inspire future studies regarding mitigation methods. Our studies found a robust low-pressure region on the edges of turbine blades, which could cause cavitation in the runner region, which would extend through the draft tube, and high magnitude of pressure fluctuations were observed in the center of the draft tube.

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