Lynch B.,Gamma Technologies Inc.
ASME 2015 Internal Combustion Engine Division Fall Technical Conference, ICEF 2015
Durability is a prime concern in the design of hydraulic systems and fuel injectors [1-3] thus an accurate prediction of impact velocities between components and the flow through them is essential to assessing concepts. Simulation of these systems is difficult because the geometries are complex, some volumes go to zero as the components move, and the flow at a single operating condition generally spans Reynolds numbers less than 1 to more than 104[4-8]. As a result of these challenges, experimental testing of prototypes is the dominant method for comparing concepts. This approach can be effective but is far more costly, time consuming, and less flexible than the ability to run simulations of concepts early in the design cycle. A validated model of a fuel injector built from publicly available data  is used to present a new approach to modelling hydraulic systems which overcomes many of these obstacles. This is accomplished by integrating several commercially available tools to solve the physics specific to each area within the fuel injector. First, the fuel injector is simulated using a 3D CFD simulation integrated with a 1D CFD system model. The flow in various regions of the injector is then analyzed to determine if the fluid models in these areas can be simplified based on the flow regime. Based on this analysis, a combination of models is assembled to improve the quality of the simulation while decreasing the time required to run the model. The fuel injector is simulated using a multibody dynamics model coupled to a reluctance network model of the solenoid and several fluid models. The first is a 3D CFD simulation which uses novel mesh refinement techniques during runtime to ensure high mesh quality throughout the motion of components, to resolve the velocity profile of laminar flows, and to satisfy the requirements of the RNG k-ε turbulence model and wall functions. This approach frees the analyst from defining the mesh before runtime and instead allows the mesh to adapt based on the flow conditions in the simulation. Due to the highly efficient meshing algorithm employed, it is possible to re-mesh at each timestep thus ensuring a high quality structured mesh throughout the simulation duration. Then a 3D FEM solution to the Reynolds Equation and a statistical contact model is employed to solve for the squeeze films between components and to allow separation and contact between bodies in the control valve. These detailed simulations are integrated with a 1D flow model of the fuel injection system. The results from the detailed coupled simulations are compared to the results from simpler 1D models and measured data to illustrate under which operating conditions a more advanced technique incorporating 3D CFD is worth the additional computational expense versus a traditional 1D model. Copyright © 2015 by ASME. Source
Almeida F.L.,MWM International Motores Ltda. |
Capana G.H.,MWM International Motores Ltda. |
De Moraes H.F.,MWM International Motores Ltda. |
Sokolowski D.,Gamma Technologies Inc.
SAE Technical Papers
A great part of the projects in the powertrain area are focused on the development of more efficient thermal applications. In the end, efficiency is pursued, since the aim is to achieve a sustainable design with low fuel consumption. Thus, vehicles which present lower fuel consumption are demanded by customers. Additionally the emission standards have been reducing the limits of CO2 emissions to very low levels, which drive engineers to develop vehicles with lower fuel consumption. In summary, the product should now please a more demanding worldwide customer profile as the global economy grows. Vehicle design processes should consider fuel consumption sensitivity taking into account the combined engine and drive train systems at early stages. Frequently the actual fuel consumption can only be confirmed when the first prototype is assembled in order to validate the adopted solutions. On the other hand, project timing is another dominant constraint, even when using planning of experiments (DoE) not all proposed designs can be tested. In this sense, the use of numerical simulation resources has been more and more utilized to reduce project timing. A vehicle simulation of a 4 cylinder Diesel internal combustion engine (ICE) coupled with the driveline of the vehicle, including its accessories, was developed utilizing the numerical 1D model, built in GT-Suite, a Gamma Technologies, Inc. code. A multi-body dynamics method was used with explicit consideration of accessory loads and the engine, which was represented by its maps evaluated at the dyno, namely BMEP, FMEP and BSFC. The model calibration was done using some route acquired data in order to reproduce the measured fuel consumption under some specific vehicle cruise conditions and 3 accelerations ramp situations. The pedal position was assigned by a PID controller representing a virtual driver's behavior. The gear shift schedule was calculated inversely by inspection pursuing a reasonable correlation of the simulated and measured fuel rates. The aerodynamics features and the rolling resistance coefficient were adopted based on information provided by the customer and the dynamic tire radius were inversely calculated using GPS vehicle speed data, engine speed and drive line ratios. This paper presents a study of the impact of accessory loads in a physically-representative way. Their loads have been considered via their power consumption curve. Each one has been studied and modeled in order to get a representative power curve shape over the relevant speed range for the engine. Then, they were all included in the 1D dynamic model. The final numerical model presented 6% of max difference in total fuel consumption in comparison to measurements for all 6 cruise situations without the need of any calibration adjustment, which is a usual practice worldwide. The acceleration behavior of the model presented a max difference of 7% (with a minimum of 2%) in comparison to measurements in terms of acceleration times and vehicle displacements. The aforementioned results were considered excellent from the perspective of the adopted 1D approach. The model has already served as a good basis to evaluate the contribution of each accessory load on the total fuel consumption in order to provide technical basis for a system optimization, which might lead to an eventual modification of the accessory design. Last but not least, it may help with the accessory supplier competition. Copyright © 2012 SAE International. Source
Kersey J.,Gamma Technologies Inc. |
Loth E.,University of Virginia |
Lankford D.,Aerospace Testing Alliance
A methodology for simulating two-way multiphase coupling of mass, momentum, and energy was developed to investigate the effect of droplet mass and heat transfer on one-dimensional shock waves. The numerical approach employed a conservative formulation for the gas and a Lagrangian formulation for the particles. The approach was verified for one-way heat transfer, evaporation and condensation for low-speed flows, and for two-way shock attenuation for solid particles and small evaporating drops (for which breakup is not expected and internal temperature gradients are weak). Parametric studies were conducted to investigate the coupling physics, and, surprisingly, finite rate evaporation and two-way coupling were found to increase the rate of shock attenuation and reduce the postshock gas temperature for mass loadings as small as 0.5%. Larger drops led to long regions of nonequilibrium as did, unexpectedly, effects of evaporation. Copyright © 2010. Source
Bissett E.J.,Gamma Technologies Inc. |
Kostoglou M.,Aerosol and Particle Technology Laboratory |
Kostoglou M.,Aristotle University of Thessaloniki |
Konstandopoulos A.G.,Aerosol and Particle Technology Laboratory |
Konstandopoulos A.G.,Aristotle University of Thessaloniki
Chemical Engineering Science
In the 1D modeling of flow in the channels of wall-flow monoliths used in diesel particulate filters for engine exhaust emissions control, it is common to use friction coefficients and Nusselt numbers from idealized 2D/3D channel flows with zero wall flow. This practice implicitly makes the additional approximation that the actual velocity and scalar (temperature or species concentrations) profiles within the channels are little affected by nonzero wall flow. There is extensive related research in the filtration literature for the simpler geometries of circular tubes and parallel planes that exposes much more complex and interesting effects as the wall Reynolds number, Re w, increases. Here we extend these results to the 3D geometry of square channels appropriate for wall-flow monoliths. We solve for the fully developed laminar flow, and heat transfer, within long square channels with porous walls and uniform wall velocity. Results are generated for the appropriate parameter range applicable for the diesel particulate filter application which provide the corrected friction coefficients and Nusselt numbers for nonzero Re w. Furthermore, we confirm the observation, from prior work on the simpler geometries that there exists a limiting Re w beyond which there is no fully developed flow for the inlet channels (wall suction). Implications for modeling diesel particulate filters are discussed. © 2012 Elsevier Ltd. Source
Agency: Department of Defense | Branch: Office for Chemical and Biological Defense | Program: SBIR | Phase: Phase II | Award Amount: 413.93K | Year: 2005
DNA microarray technology, in combination with statistical and predictive modeling tools, could be used to evaluate thousands of genes against distinct gene expression patterns induced by chemical/biological agents to provide early identification and speed therapeutic intervention. The overall objective of this Phase II effort is to leverage existing public domain resources and commercial tools to provide the Army with a comprehensive data management system with integrated statistical and pattern recognition tools capable of: 1) Identifying agent specific gene profile biomarker signatures; 2) Teasing out exogenous factors such as ingested food, stressors, etc.; 3) Discriminating naturally occurring diseases from weaponized biological agents; and 4) Linking gene expression responses to physiological responses. Similar needs for a data management system with statistical and visualization tools exists in the private sector, specifically basic research and the pharmaceutical industry. The secondary objective of Phase II is to develop a product that meets private sector needs as well as those of the Army. At the conclusion of Phase II, Alpha-Gamma will have a product (bioCAT) ready for commercialization in the private sector.