Technical Paper collections have been re-named for better clarity and alignment.x

Your Selections

Pressure
Show Only

Collections

File Formats

Content Types

Dates

Sectors

Topics

Authors

Publishers

Affiliations

Committees

Events

Magazine

   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Numerical Modeling of Spray Formation under Flash-boiling Conditions

ANSYS Inc-Mingyuan Tao, Long Liang, Yue Wang, Ellen Meeks
  • Technical Paper
  • 2020-01-0328
To be published on 2020-04-14 by SAE International in United States
Flash boiling occurs in sprays when the ambient gas pressure is lower than the saturation pressure of the injected fuel. In the present work, a numerical study was conducted to investigate solid-cone spray behaviors under various flash-boiling conditions. A new spray cone angle correlation that is a function of injection parameters was developed and used for spray initialization at the nozzle exit to capture plume interactions and the global spray shape. The spray-breakup regime control was adjusted to enable catastrophic droplet breakup, characterized by Rayleigh-Taylor (RT) breakup, near the nozzle exit. The model was validated against experimental spray data from five different injectors, including both multi-hole and single-hole injectors, with injection pressure varying from 100 to 200 bar. Different fuels, including iso-octane, n-heptane, n-pentane, ethanol, and n-butanol, were investigated under a wide range of flash-boiling conditions, in which flash boiling was induced by high injected fuel temperature, ranging from 323 to 493 K, and/or low ambient gas pressure, ranging from 0.1 bar to atmospheric. It is found that flash boiling can significantly increase the spray…
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Transient thermal behavior of dry clutch under non-uniform pressure condition

Shanghai Jiao Tong University-Yongchun Jin, Li Chen, Cheng Cheng
  • Technical Paper
  • 2020-01-1418
To be published on 2020-04-14 by SAE International in United States
Accuracy of thermal models is critical to clutch design in case of excessive temperatures due to large amounts of friction heat generated in the narrow space. Pressure distribution on the clutch friction interface is an important factor affecting heat flux distribution, thus affecting temperature distribution. But no previous literature reported how the pressure is distributed on dry clutches. This study conducts an experiment to obtain the pressure distribution for one typical dry clutch equipped with a set of diaphragm spring. Considering that the frictional interface is in contact, ordinary pressure sensors are not applicable because they have to separate the interface for a certain distance. Addressing this difficulty, this study makes use of pressure sensitive film and acquires data based on image processing techniques. Thereafter, a polynomial model with dimensionless parameters is developed to fit the pressure distribution. Thus, the non-uniform pressure model is worked out. After that, the proposed pressure model is applied to a thermal model based on finite element method. In addition, two conventional thermal models, which use uniform pressure and uniform…
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Isobaric combustion at a low compression ratio

King Abdullah Univ of Science & Tech-Aibolat Dyuisenakhmetov, Harsh Goyal, Moez Ben Houidi, Bengt Johansson
Saudi Aramco-Jihad Badra
  • Technical Paper
  • 2020-01-0797
To be published on 2020-04-14 by SAE International in United States
In a previous study, it was shown that isobaric combustion cycle, achieved by multiple injection strategy, is more favorable than conventional diesel cycle for the double compression expansion engine (DCEE) concept. In spite of lower effective expansion ratio, the indicated efficiencies of isobaric cycles were approximately equal to those of a conventional diesel cycle. Isobaric cycles had lower heat transfer losses and higher exhaust losses which are advantageous for DCEE since additional exhaust energy can be converted into useful work in the expander. In this work, the performance of isobaric combustion cycles in terms of indicated efficiency, emissions, and energy flow distribution is compared to the conventional diesel cycle but at a relatively lower compression ratio. A standard 17-compression ratio piston is replaced by a low 11.5-compression ratio piston. GT power simulations suggest that a low compression ratio of the high-pressure unit of DCEE could lead to an improvement in efficiency. The current study consists of two sets of experiments. In the first set of experiments, the intake pressure and intake temperatures are increased to…
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Minimizing Disturbance Detection Time in Hydraulic Systems

General Motors-Paul Otanez, Ramadityanand Bhogadi
  • Technical Paper
  • 2020-01-0263
To be published on 2020-04-14 by SAE International in United States
In a hydraulic system, parameter variation, contamination, and/or operating conditions can lead to instabilities in the pressure response. The resultant erratic pressure profile produces reduced performance that can lead to hardware damage. Specifically, in a transmission control system, the inability to track pressure commands can result in various types of slip and disturbances to the driveline. Therefore, it is advantageous to identify such pressure events and take remedial actions. The challenge is to detect the condition in the least amount of time while minimizing false alarms. In this study, cross and auto-correlation techniques are evaluated for the detection of pressure disturbances. The performance of the detectors is measured in terms of speed of detection and robustness to: 1) measurement noise, and 2) disturbance parameter uncertainty (frequency and amplitude). The implications in terms of computations and memory utilization of implementing the detectors in real-time embedded systems are also discussed. Both simulation and hardware examples are presented. The hardware experiment is performed in a hydraulic system with low damping composed of a solenoid and a regulator valve…
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Effect of geometry variations in a polymer electrolyte membrane fuel cell

Siemens Digital Industries Software-Carlo Locci, Chris Lueth, Huong Nguyen, Karin Frojd
  • Technical Paper
  • 2020-01-1174
To be published on 2020-04-14 by SAE International in United States
Water transport at high current densities is of main concern for polymer electrolyte membrane fuel cells. The water content of the membrane has to be high enough to provide maximum electrical conductivity and thus optimal stack performance. Dry-out may also lead to membrane degradation. However, a too high level of humidity leads to cell flooding, blocking the air and fuel flows to the catalyst sites and thus the reactions, resulting in a drop in efficiency. Fuel cells water transport physics requires further investigation due to its complexity [1,2] and numerical modelling can improve the fundamental understanding of the phenomena. In this work, an optimization algorithm is used to optimize a fuel cells geometry to improve the temperature distribution and the pressure drop. In addition, the effect of the several geometric configurations on the water management is discussed. The PEM fuel cell is modelled in Siemens Simcenter STAR-CCM+ [3]. Anode and cathode GDL and catalyst layers are modelled as porous media, with electrochemical reactions in the catalyst layer. The membrane is modelled as a solid block…
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Emissions benefits of Group Hole Nozzle Injectors under Conventional Diesel Combustion Conditions

Marquette University-Adam Dempsey
Univ. of Wisconsin Madison-Aravindh Babu, Daniel Staaden, Sage Kokjohn
  • Technical Paper
  • 2020-01-0302
To be published on 2020-04-14 by SAE International in United States
This work explores the effectiveness of common rail fuel injectors equipped with Grouped Hole Nozzles (GHNs), in aiding the spray breakup and reducing particulate matter (PM) emissions of Conventional Diesel Combustion (CDC) engines, while maintaining reasonable Oxides of Nitrogen (NOx) levels. Parallel (pGHN), converging (cGHN) and diverging (dGHN) - hole GHNs were studied and the results were compared to a conventional, single hole nozzle (SHN) with the same flow area. Based on an extensive study of the literature, the following parameters are chosen for study: orifice diameter, orifice separation within a group, number of groups, angle between orifices, included angle of the orifices themselves and the boundary conditions (load, injection pressure, intake pressure and Start of Injection (SOI) timing). The study was conducted on a single cylinder medium-duty engine to isolate the effects of the combustion from multi-cylinder effects and the conditions were chosen to be representative of a typical mid-load operating point for an on-road diesel engine. The effects of injection pressure and SOI are explored and the tradeoffs between these boundary conditions are…
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Numerical investigations on strong knocking combustion under compression ignition conditions

State Key Lab Of Engines-JIAYING PAN
Tianjin Univ-Lin Chen, Jianfu Zhao
  • Technical Paper
  • 2020-01-1137
To be published on 2020-04-14 by SAE International in United States
Homogeneous charge compression ignition (HCCI) combined with high compression ratio is an effective way to improve engines’ thermal efficiency. However, the severe thermodynamic conditions at high load may induce knocking combustion thus damage engine body. In this study, compression ignition knocking characteristics were parametrically investigated through RCM experiments and simulation analysis. First, the knocking characteristics were optically investigated. The experimental results show that there even exists detonation when the knock occurs thus the combustion chamber is damaged. Considering both safety and costs, the effects of different initial conditions were numerically investigated and the results show that knocking characteristics is more related to initial pressure other than initial temperature. The initial pressure have a great influence on peak pressure and knock intensity while initial temperature on knock onset. Further analysis shows that knock intensity is mainly related to the energy density of the in-cylinder mixture and energy density is higher under higher pressure conditions. Then the effects of different cylinder wall temperature on the local auto-ignition thus knocking characteristics were further discussed. The results show that…
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Cost-efficient Cathode Air Path for PEM Fuel Cell systems

MANN+HUMMEL GmbH-Michael Harenbrock, Alexander Korn, Andreas Weber
MANN+HUMMEL Innenraumfilter GmbH & Co.KG-Eva Hallbauer
  • Technical Paper
  • 2020-01-1176
To be published on 2020-04-14 by SAE International in United States
Fuel cell technology will play a major role in reducing transportation-related emissions, especially in sectors where battery-electric powertrains will face severe challenges, e.g. in heavy-duty, long-haul applications, as it decouples system weight from electric driving range. To achieve the required fuel cell stack lifetime, the supply of clean air is essential, especially with low Platinum catalyst loads required to achieve the DOE cost targets. As gases as NOx, SO2 and NH3 can poison the catalyst, leading to - often irreversible - loss in power supply from the stack, these must be captured by use of tailor-made activated carbons. Research on real-life concentrations of these contaminants under different driving patterns and road profiles leads to the knowledge-based design of Cathode Air Filter elements. Cost-efficient Balance-of-Plant components are required to integrate the filter into the full Cathode Air path. To prevent flooding of components like air filter, humidifier, or the stack itself, water separators are integrated at different position inside the system. Air ducts are designed in a way to operate under the different temperature and pressure…
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

High Strain Rate Tensile Response of Caprine Muscle Tissue using Polymeric Split Hopkinson Pressure Bar

DBATU Lonere-Somnath Hanumant Kadhane
Dr. B.A. Technological University-Hemant Warhatkar
  • Technical Paper
  • 2020-01-0519
To be published on 2020-04-14 by SAE International in United States
Soft tissues such as muscles and skin in human body are exposed to varying strain rates under dynamic loading due to high speed automotive accidents. The prediction of impact-induced injuries during automotive accidents requires a thorough understanding of mechanical behaviour of soft tissues at high strain rates for accurate medical intervention and crash simulations. Studies on soft tissue responses under dynamic loading are limited in available literature. Uniaxial tensile tests at high strain rates (500 s-1- 4000 s-1) were conducted on caprine lower extremity muscles using polymeric tensile split Hopkinson pressure bar (SHPB) apparatus. Polymeric bars were used in SHPB as impedance is closer to the soft tissues. The attenuation and dispersion in waves are corrected using isolated incident bar tests. The dynamic tensile test results show that stress-strain response is non-linear, concave upward and dependent on strain rate. These obtained results may further be used to develop finite element human body models and safety systems for human body in crash scenario.
   This content is not included in your SAE MOBILUS subscription, or you are not logged in.

Anisotropic material behavior and design optimization of 3D printed structures

University of Kentucky-Jordan Garcia, Robert Harper, Coilin Bradley, John Schmidt, Y Charles Lu
  • Technical Paper
  • 2020-01-0228
To be published on 2020-04-14 by SAE International in United States
Traditional manufacturing processes such as injection or compression molding are often enclosed and pressurized systems that produce homogenous products. In contrast, 3D printing is exposed to the environment at ambient (or reduced) temperature and atmospheric pressure. Further, the printing process itself is mostly “layered manufacturing”, i.e., it forms a three-dimensional part by laying down successive layers of materials. Those characteristics inevitably lead to inconsistent microstructure of 3D printed products and thus cause anisotropic mechanical properties. In this paper, the anisotropic behaviors of 3D printed parts were investigated by using both laboratory coupon specimens (bending specimens) and complex engineering structures (A-pillar). Results show that the orientation of the infills of 3D printed parts can significantly influence their mechanical properties. Parts with 0-degree filament orientation are seen to have the most favorable responses, including Young’s modulus, maximum strength, failure strain, and toughness. The findings also suggest that the 3D printed products could be theoretically “designed” or “tailored” by adjusting the infill angles to achieve optimal performance. The 3D printed A-pillar structure has been designed by utilizing the…