Search Results

Threaded, potted inserts are commonly used as a standard connecting element for sandwich components, which are used for aircraft interior. Since they often offer the only detachable connection, they are used in very high quantities. To ensure a material bond between the inserts and the honeycomb structure, the joint is filled with adhesive. Despite the high number of inserts, this process is performed manually. Recent research has shown new approaches for automated gripping and placement of the inserts by an industrial robot that yield high potential for cost savings and increased productivity. Automated adhesive insertion, so-called potting, has not been considered so far but is an essential contribution to the full automation of the entire process chain. The amount of adhesive varies depending on the type of insert and its position on the honeycomb structure.

In this work two concepts of automotive power trains are analyzed and compared using multi-physical simulation. The focus of the presented investigation is the energy consumption improvement due to the electrification of the air conditioning (AC) system in a sport utility vehicle (SUV). A full vehicle model representing a real SUV with conventional power train (internal combustion engine (ICE), clutch, gearbox, multi speed transmission gear, differential and driving axles) is developed. This conventional SUV model gets compared with a mild hybrid concept including a starter-generator, a battery and an inverter fed drive with control unit. Mechanical, electrical and detailed thermal effects are considered in the simulations. By comparing the energy consumptions, the potential of efficiency improvement due to the implementation of an electrified AC system is shown at the example of a state-of-the-art SUV.

Requirements to future internal combustion engines (ICEs) regarding sustainability and efficiency are continuing to rise while on the other hand, pollutant emission regulations are continuously tightened. Dual-fuel combustion (DFC) of diesel and natural gas is an approach to reduce soot emissions while still profiting from the high efficiency of the diesel combustion process. Using natural gas as the main fuel also helps to reduce carbon dioxide (CO2) emissions due to the favorable C/H-ratio of methane (CH4) as its primary constituent. To reduce both pollutant and greenhouse gas emissions further, diesel can be replaced by an e-fuel. The use of C1-oxygenates – such as polyoxymethylene dimethyl ether (POMDME or “OME”) – as pilot fuel promises to reduce both soot and nitrogen oxide (NOx) emissions. For the present investigation, a 4.5l tractor diesel engine has been converted to a biogas-OME dual-fuel engine. A fully variable valve train has been integrated into the cylinder head.

Recent research activities have greatly expanded the understanding of HCCI, its controlling mechanisms, and operation strategies. However, substantially more work is required before HCCI engines will be ready for production. This includes development of a methodology for feedback and closed-loop control of the fuel and air systems to realize HCCI combustion over the speed load range in a production vehicle. In this paper, we use in-cylinder ion sensing to extract the timing of start of combustion and monitor other combustion information such as knocking as feedback signals for closed loop control of HCCI engines. The ion sensor we use is modified from the existing glow plug. This method will minimize the cost relative to an in-cylinder pressure sensor and signal conditioning circuitry while providing equivalent combustion information for the ECU to control the engine.

An inexpensive piezoelectric pressure sensor capable of detecting the internal combustion peak pressure position has been developed by Oceana Sensor Technologies for mass production. This paper describes the principle, structure and the Finite Element model of the designed sensor. A state-space model of the piezoelectric input/output system is extracted based on model reduction method. The performance of this sensor is evaluated using test engine and compared with a commercially available sensor.

Over the past years, the question as to what may be the powertrain of the future has become ever more apparent. Aiming to improve upon a given technology, the internal combustion engine still offers a number of development paths in order to maintain its position in public and private mobility. In this study, an innovative combustion process is investigated with the goal to further approximate the ideal Otto cycle. Thus far, similar approaches such as Homogeneous Charge Compression Ignition (HCCI) shared the same objective yet were unable to be operated under high load conditions. Highly increased control efforts and excessive mechanical stress on the components are but a few examples of the drawbacks associated with HCCI. The approach employed in this work is the so-called Spark Assisted Compression Ignition (SACI) in combination with a pre-chamber spark plug, enabling short combustion durations even at high dilution levels.

The prediction of ignition delay times is very useful during the development phase of internal combustion engines. When it comes to biofuels such as ethanol and its blends with gasoline, its importance is enhanced, especially when it comes to flex-fuel engines and the need to address current and future emissions legislations and efficiency goals. The ignition delay time measured as the angular difference between the spark discharge time, as commanded by the ECU and a relevant fraction of fuel mass burned (usually, 2, 5 or 10%). Experimental tests were performed on a downsized state-of-the-art internal combustion engine. Engine speed of 2500 rpm, with load of 6 and 13 bar IMEP were set for investigation. Stoichiometric operation and MBT or knock-limited spark timings were used, while valve overlap was varied, in order to address the effects of scavenging and residuals on ignition delay times.

The challenge to find optimal solutions regarding energy efficiency in vehicle systems such as transmissions, engine and chassis involves the understanding of friction torque, friction losses and loading conditions interactions. Design variables such as internal dimensions, component profile and roughness will lead to a final component from which needs input energy to start and maintain movement. Even a component without load requires a minimal amount of energy and assembled in a vehicle will contribute to fuel consumption and emissions. The same component over loading conditions will turn these values higher due to the energy balance. Using engineering modeling techniques, the loading conditions, such as radial forces and rotation speed were implemented by parametric analysis and a dynamic model was built to obtain the variable contribution in energy-based design.

This paper presents some simulative and experimental results of a low emission small two-stroke cycle engine. A 23.6cc air-head stratified scavenging engine complied with CARB Tire II exhaust emission regulation was used as a base engine. A mechanism of air/fuel mixture short-circuiting cause of THC emission was investigated by numerical simulation by means of Computational Fluid Dynamics (CFD) for the base engine. To reduce the air/fuel mixture short-circuiting, port design was improved and evaluated by means of CFD. New engine performance adopted the CFD results was compared with that of the base engine. As the results of the investigation, the new engine performance at a rated speed was achieved 40% reduction of THC emission having almost same power compared with the base engine. The new 23.6cc air-head stratified scavenging two-stroke cycle engine can meet to EPA Phase2 and CARB Tire III regulations without catalyst.

Emerging technologies are making hybrid vehicles more popular in today’s world, in which sustainability and reduced carbon emissions are primary development requisites. These vehicles satisfy these demands by combining an internal combustion engine with an electric motor, together providing the power needed for movement to happen. Understanding how the power from each source is combined and used is the basis to select the combustion engine and the electric motor. Moreover, its advantages relative to a combustion-only vehicle can be compared. In this paper we investigate the powertrain of different types of hybrid vehicles. They are compared to combustion-only vehicles regarding engine size and transmission systems, as well as fuel consumption. This study provides an understanding of how hybridization affects the design parameters of the powertrain and its impacts on the future of mobility.

Diesel engines produce harmful exhaust emissions and high exhaust noise levels. One way of mitigating both exhaust emissions and noise is via the use of after treatment devices such as Catalytic Converters (CC), Selective Catalytic Reducers (SCR), Diesel Oxidation Catalysts (DOC), and Diesel Particulate Filters (DPF). The objective of this investigation is to characterize and simulate the acoustic performance of different types of filters so that maximum benefit can be achieved. A number of after treatment device configurations for trucks were selected and measured. A measurement campaign was conducted to characterize the two-port transfer matrix of these devices. The simulation was performed using the two-port theory where the two-port models are limited to the plane wave range in the filter cavity.

A cooling fan is an essential device of the engine cooling system which is used to remove the heat generated inside the engine from the system. An essential element for successful fan designs is to evaluate the pressure over the fan blade since it can generate annoying noices, which have a negative impact on the fan’s performance and on the environment. Reducing the acoustic surface power will assist in building improved designs that comply with standards and regulations in achieving a more quiet environment. The usage of computational fluid dynamics (CFD), with support of mesh morphing, can provide simulation study for optimizing the shape of a fan blade to reduce the aeroacoustic effects. The investigation process will assist in examining and analyzing the acoustic performance of the prototype, impact of different parameters, and make a solid judgement about the model performance for improvement and optimization.

The combustion efficiencies of diesel oxidation catalysts (DOC) targeted for use in the heat-up role of active diesel particulate filter (DPF) systems are investigated. Light-off tests using synthetic gases and fuel injection studies on light and heavy duty engines, both before and after thermal aging, are carried out. These evaluations are used to demonstrate differences in activity between closely related Pt-only and Pt/Pd formulations. Post-mortem analyses are conducted to determine the basis for the performance differences observed during the fuel injection studies. These analyses include measurement of the accumulation of carbonaceous compounds on catalyst surfaces which are associated with incomplete combustion of the injected fuel. Aging cycles developed for DOC+DPF systems incorporating heat-up by in-exhaust fuel injection on heavy-duty diesel engines are presented. The impact of these aging cycles on the performance of a Pt/Pd catalyst are summarized.

To determine the appropriateness of specifying the allowable amount of hydrogen leakage upon collision based on the amount of leakage with generated heat equivalent to that of gasoline vehicles and CNG vehicles, we investigated the safety of each type of fuel when flame ignites. Our results confirm that the flame lengths for hydrogen and methane are almost equal, and there is no remarkable difference between them in terms of the distance for assuring safety. Furthermore, we confirmed that the irradiant heat flux from the mixed burning of hydrogen flame with liquid flammable materials is almost equal to that of the spray flame of gasoline. Thus, no clear difference was found between various types of fuel. Therefore, it is appropriate to specify the allowable amount of hydrogen leakage based on the amount of leakage with generated heat equivalent to that of other types of fuel.

In this study, hydrogen was leaked using a nozzle that simulated an actual leak port (with varied materials and diameters), and the possibility of ignition was verified to collect data useful for establishing standards for the allowable flow rate of hydrogen leakage on receptacle. With the flow rate of a hydrogen leak set at 250 mL/h(NTP) (hereinafter mL/h is NTP condition) or less, ignition of leaked hydrogen with an electric spark and a small methane-fueled flame was attempted. The results confirmed that ignition of 200 mL/h of hydrogen was not achieved under tested conditions. In some cases, hydrogen at a flow rate of 250 mL/h was ignited. Tissue paper placed in contact with the flame at a flow rate of 250 mL/h combusted, resulting the flame went out almost immediately. Therefore, it was determined that a hydrogen leak at approximately 200 mL/h that occurred in this test is a very low possibility of ignition or spreading.

This paper focuses on the applicability of numerical prediction of sound radiation caused by an axial vehicle cooling fan. To investigate the applicability of numerical methods, a hybrid approach is chosen where first a CFD simulation is performed and the sound radiation is calculated in a second step. For the acoustic simulation an integral method described by Ffowcs-Williams-Hawkings is used to predict the sound propagation in the far-field. The simulation results are validated with experiments. The corresponding setup in experiments and simulation represents an overall system which includes the cooler, the cooling fan and a combustion engine dummy. To optimize the economical applicability in terms of simulation setup and run time, different approaches are investigated. This includes the simulation of only one blade using a periodic boundary condition as compared to the whole fan geometry. In the CFD simulation an SAS-turbulence-model is applied.

The optimization of mixture formation in diesel engines requires precise knowledge of the mechanisms of spray atomization and the correlation between injection and engine operating conditions and the parameters of the injection spray. The influence of the fuel properties will be shown considering both the temperature in the high-pressure chamber and the injection pressure as important variation parameters. A global temporally resolved visualization of the injection sprays is realized and information about the droplet size distributions in the spray are obtained by means of locally highly resolved laser-based measurement techniques. The low proportion of low-boiling components in heavy fuels is a significant cause for a deteriorated mixture formation. Higher temperature in the combustion chamber and higher injection pressure have a positive influence on the spray development as well as fuel evaporation.

The drag reduction effect was investigated with regard to the bed and rear flap variation for a pickup truck through design of experiments process. The design factors were the bed length, bed height, rear flap length, and flap inset with three levels, and the noise factor was the yaw angle. The signal-to-noise ratio calculation was introduced to evaluate the low-drag performance under a crosswind. Analysis of variance indicated the significant interaction effect between the bed length and bed height. Since the bed flow of the short with low bed was attached to the tailgate, which increased the drag coefficient and lowered the S/N ratio. The rear flap add-on at the rear edge of a roof was effective to reduce the drag coefficient. However, the sensitivity of the flap length variation on the drag reduction was not significant. The flap inset had a negative effect on the drag reduction as it lowered the inset area pressure of the cabin back surface.

In recent years three-wheel camber vehicles, with two wheels in the front and a single rear wheel, have been growing in popularity. We call this kind of vehicle A “Leaning Multi Wheel category Vehicle” (hereinafter referred to as a “LMWV”). A LMWV has various characteristics, but one of them stands out in particular. When a LMWV is cornering, if one of the front wheels passes over a section of road surface with a low friction coefficient, there is very little disturbance to the vehicle’s behavior and can continue to be driven as normal. However, there has been no investigation into why these vehicles have this particular characteristic. Consequently, in this paper an investigation was carried out in order to determine the behavior of a LMWV in this situation. First, measurements were taken using an actual vehicle to confirm the situation described above.