Study on the Intake Valve Close Timing Misalignment Between the Maximum Volume Efficiency and the None Backflow on a Single Cylinder Diesel Engine

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Fushui Liu ◽  
Zhongjie Shi ◽  
Yang Hua ◽  
Ning Kang ◽  
Yikai Li ◽  
...  
Keyword(s):  
Diesel Engine ◽  
High Speed ◽  
Three Dimensional ◽  
Intake Valve ◽  
Maximum Volume ◽  
Single Cylinder ◽  
Gradual Process ◽  
The Mean ◽  
The Relationship ◽  
Volume Efficiency

Since the intake valve close timing (IVC) directly determines the amount of displacement backflow and the amount of fresh charge trapped in the cylinder, optimizing the IVC is important to improve the performance of the diesel engine. In this paper, the relationship between the IVC and the displacement backflow of the cylinder at the high-speed condition was studied by establishing a one-dimensional (1D) gas dynamic model of a single-cylinder diesel engine. The results show that the forward airflow mass of intake and the backflow increase as the IVC retards, and the airflow mass trapped in cylinder increases at first and then decreases. It is interesting to find that the backflow does not equal zero when the air mass trapped in cylinder is the largest, which is different from the traditional optimizing strategy on the IVC. That is to say, there exists a misalignment between the maximum-volume-efficiency IVC and the none-backflow IVC. To further verify this interesting misalignment, the airflow characteristics at the optimized IVC condition are studied by establishing a three-dimensional (3D) simulation. It is found that the appearance of backflow is a gradual process, and there exists an overall backflow when the engine volume efficiency reaches its maximum value. In addition, the misalignment is reduced as the mean valve-closing velocity increases. The misalignment equals to 0 only if the mean valve-closing velocity approaches infinity.

scholarly journals A Field Measurement Based Wind Characteristics Analysis of a Typhoon in Near-Ground Boundary Layer

Atmosphere ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 873
Author(s):  
Dandan Xia ◽  
Liming Dai ◽  
Li Lin ◽  
Huaifeng Wang ◽  
Haitao Hu
Keyword(s):  
Turbulence Intensity ◽  
Field Measurement ◽  
Three Dimensional ◽  
Wind Data ◽  
Statistical Characteristics ◽  
Gust Factor ◽  
Characteristics Analysis ◽  
Wind Characteristics ◽  
The Mean ◽  
The Relationship

The field measurement was conducted to observe the wind field data of West Pacific typhoon “Maria” in this research. With the application of ultrasonic anemometers installed in different heights (10 m, 80 m, 100 m) of the tower, the three dimensional wind speed data of typhoon “Maria” was acquired. In addition, vane-type anemometers were installed to validate the accuracy of the wind data from ultrasonic anemometers. Wind characteristics such as the mean wind profile, turbulence intensity, integral length scale, and wind spectrum are studied in detail using the collected wind data. The relationship between the gust factor and turbulence intensity was also studied and compared with the existing literature to demonstrate the characteristics of Maria. The statistical characteristics of the turbulence intensity and gust factor are presented. The corresponding conclusion remarks are expected to provide a useful reference for designing wind-resistant buildings and structures.

Aerodynamic Characteristics Analysis of High-Speed Train on Cutting under Crosswinds

2013 ◽  
Vol 300-301 ◽  
pp. 62-67
Author(s):  
Kun Ye ◽  
Ren Xian Li
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
High Speed Train ◽  
Aerodynamic Forces ◽  
Cutting Depth ◽  
Cutting Slope ◽  
Characteristics Analysis ◽  
Relationship Of ◽  
The Relationship

Cutting is an effective device to reduce crosswind loads acting on trains. The cutting depth, width and gradient of slope are important factors for design and construction of cutting. Based on numerical analysis methods of three-dimensional viscous incompressible aerodynamics equations, aerodynamic side forces and yawing moments acting on the high-speed train, with different depths and widths of cutting，are calculated and analyzed under crosswinds，meanwhile the relationship of the gradient of cutting slope and transverse aerodynamic forces acting on trains are also studied. Simulation results show that aerodynamic side forces and yawing moments acting on the train（the first, middle and rear train）decrease with the increase of cutting depth. The relationship between transverse forces (moments) coefficients acting on the three sections and the cutting depth basically is the three cubed relation. The bigger is cutting width，the worse is running stability of train. The relationship between yawing moments coefficients acting each body of the train and the cutting width approximately is the three cubed relation. The transverse Aerodynamic forces decreased gradually with the increase of the gradient of cutting slope, the relationship between yawing moments coefficients acting each body of the train and the gradient of cutting slope basically is the four cubed relation.

scholarly journals Three-dimensional analysis of acetabular cup orientation and an evaluation of the relationship with pelvic sagittal parameters

2019 ◽  
Vol 27 (2) ◽  
pp. 230949901986122
Author(s):  
Ali Sahin ◽  
Mehmet Emin Simsek ◽  
Safa Gursoy ◽  
Mustafa Akkaya ◽  
Cetin Isik ◽  
...  
Keyword(s):  
Pelvic Tilt ◽  
Three Dimensional ◽  
Preoperative Assessment ◽  
Statistical Correlation ◽  
Acetabular Cup ◽  
Pelvic Parameters ◽  
Sagittal Parameters ◽  
The Mean ◽  
The Difference ◽  
The Relationship

Background: This study aimed to evaluate the effect of total hip arthroplasty (THA) on sagittal pelvic parameters and to evaluate the effect of sagittal pelvic parameters on acetabular cup orientation. Methods: The study included 86 patients who underwent THA for a diagnosis of unilateral coxarthrosis between 2011 and 2015. Measurements were taken of the preoperative and postoperative acetabular cup inclination (ACI), anteversion, and sagittal pelvic parameters. The effect of THA on sagittal pelvic parameters and the effects of the sagittal pelvic parameters on acetabular cup orientation were investigated. Results: The sagittal pelvic tilt values calculated were mean 9.7° ± 6.3° (2°; 23°) preoperatively and 11.0° ± 6.1° (2°; 25°) postoperatively. The increase in postoperative pelvic incidence (PI) values was determined to be statistically significant ( p < 0.05). The preoperative PI values had no significant effect on ACI, but in cases with high preoperative PI values, a tendency to high anteversion values was determined. The mean inclination values were found to be 40.2° ± 11.0° in the low PI group, 41.7° ± 7.4° in the normal PI group, and 44.1° ± 8.3° in the high PI group. As no increase in inclination values was observed with an increase in PI values, no statistical correlation was determined ( p = 0.343). Average of anteversion values in the low PI group was 9.2° ± 13.7°, in the normal PI group 19.3° ± 10.5°, and in the high PI group 21.1° ± 12.5°. The difference between the groups was statistically significant ( p = 0.001). Conclusion: Evaluating the results of this study, it can be concluded that varying PI values do affect the acetabular cup anterversion in THA. So, preoperative assessment of PI values is important in preventing postoperative acetabular cup malposition.

scholarly journals A Study on the Relationship between the Design of Aerotrain and Its Stability Based on a Three-Dimensional Dynamic Model

Robotics ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 96
Author(s):  
Quang Huan Luong ◽  
Jeremy Jong ◽  
Yusuke Sugahara ◽  
Daisuke Matsuura ◽  
Yukio Takeda
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Three Dimensional ◽  
Vehicle Body ◽  
Directional Stability ◽  
Rigid Body Model ◽  
Body Design ◽  
The Stability ◽  
New Generation ◽  
The Relationship

A new generation electric high-speed train called Aerotrain has levitation wings and levitates under Wing-in-Ground (WIG) effect along a U-shaped guideway. The previous study found that lacking knowledge of the design makes the prototype unable to regain stability when losing control. In this paper, the nonlinear three-dimensional dynamic model of the Aerotrain based on the rigid body model has been developed to investigate the relationship between the vehicle body design and its stability. Based on the dynamic model, this paper considered an Aerotrain with a horizontal tail and a vertical tail. To evaluate the stability, the location and area of these tails were parameterized. The effects of these parameters on the longitudinal and directional stability have been investigated to show that: the horizontal tail gives its best performance if the tail area is a function of the tail location; the larger vertical tail area and (or) the farther vertical tail location will give better directional stability. As for the lateral stability, a dihedral front levitation wing design was investigated. This design did not show its effectiveness, therefore a control system is needed. The obtained results are useful for the optimization studies on Aerotrain design as well as developing experimental prototypes.

Investigation of Fuel Spray Propagation, Combustion and Soot Formation/Oxidation in a Single Cylinder Medium Speed Diesel Engine

2012 ◽  
Author(s):  
Fridolin Unfug ◽  
Uwe Wagner ◽  
Kai W. Beck ◽  
Juergen Pfeil ◽  
Ulf Waldenmaier ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Diesel Engines ◽  
High Speed ◽  
Liquid Fuel ◽  
Combustion Process ◽  
Fuel Spray ◽  
Soot Concentration ◽  
Single Cylinder ◽  
Medium Speed ◽  
532 Nm

To fulfil strict emission regulations and the need for higher efficiency of future Diesel engines require an optimized combustion process. Optical investigations represent a powerful tool for getting a better understanding of the ongoing processes. For medium speed Diesel engines, optical investigations are relatively rare or not available. The “Institut für Kolbenmaschinen” (IFKM) and MAN Diesel & Turbo SE performed extensive optical in-situ investigations of the injection and combustion process of a MAN 32/44 CR single cylinder medium speed Diesel engine that provide previously unavailable insights into the ongoing processes. The optical investigations aimed on fuel spray visualization, high-speed soot luminescence measurement and two colour pyrometry applied for five combustion chamber regions. To apply the optical measurement techniques, two optical accesses were designed. Access no. 1 is placed near the cylinder liner. Access no. 2 is located close to the injector in a 46° angle to the cylinder vertical axis. An insert was used which consists of an illumination port and a visualization endoscope. Additionally some special nozzle designs were used beside the standard nozzle, which have one separated nozzle hole. This enables a simultaneous view from both optical accesses on the same flame cone. For Mie-Scattering investigation a pulsed Nd:YAG-Laser with 532 nm wavelength was used for illumination and a CCD-camera with an upstream 532 nm optical filter was used for visualization. This combination allows observing the liquid fuel distribution even after start of combustion. Penetration depth of liquid fuel spray was analysed for different swirl numbers, intake manifold pressures, injection timings and injection pressures. High-speed flame visualization was done by two CMOS cameras which were mounted at two different optical accesses with view on the same flame cone. Due to this application a simultaneous measurement of the flame distribution of two different views was possible. This enables a 3-dimensional investigation of the flame propagation process. In addition, the advanced two colour pyrometry was applied for five different regions of the same flame cone. Due to a calibration after each measurement the absolute radiant flux can be calculated and thus the absolute temperature and soot concentration. With this procedure it was possible to give a real temperature and soot concentration distribution of the flame cone. To provide more detailed information about the combustion process, selected engine operation points were simulated with a modified version of the CFD code KIVA3v-Release2 at the IFKM. The simulated results were compared to the measured data.

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