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A new latent heat storage technique for space applications developed by the DLR-ITT uses LiF as the storage medium in graphite capsules with internal capillary notches to accomodate the volume change upon melting. The receivers of solar dynamic power systems (SDPS) may contain a large number of heat pipes carrying annular such storage capsules for very effective heat transfer and thermal storage. The thermal behavior of one of these heat-pipe/latent-heat-storage elements was investigated theoretically and shall be verified experimentally, both in a geometrically and energetically 1:1 scale with respect to a 25 kWe SDPS. This paper summarizes the most important theoretical predictions and describes the planned experiment. The theoretical results show that the required heat flows are essentially achievable but subject to variation with the state of charge of the heat storage units. The relevant temperatures vary in a similar manner.

An important source for soot formation during the combustion of diesel engines with direct injection is the interaction of liquid fuel or a very rich air/fuel-mixture with the flame. This effect appears especially in modern direct injection engines where the injection is often split in a pre- and a main injection due to noise reasons. After the ignition of the pre-injected fuel a part of the main injection can interact with the flame still in liquid phase as the fuel is injected straight towards the already burning cylinder areas. This leads to high amounts of soot. The injection strategy for this experimental study overcomes this problem by separating the injections spatially and therefore on the one hand reduces the soot formation during the early stages of the combustion and on the other hand increases the soot oxidation later during the combustion. In particular an injection configuration is used which gives the degree of freedom to modify the injection in the described manner.

A new steering method to improve control during cornering is examined using a driving simulator, and the following findings were obtained. During cornering, there is a danger that it is not possible to finish curving is course out by the only differentiation steering. However, the driver can easily maintain a drift in the drift area when assisted by differentiation steering, and the behavior of the return to a straight course becomes stable. Therefore, since a remarkable effect was expected by controlling the steering method corresponding to the running condition, an examination experiment was performed. The shapes of the waves of initial steering at start up differ according to the running condition, and as a result, initial steering of the steering wheel is a two-step motion in J-turn running. In contrast, smooth steering proceeds without steps in the lane change running.

An experimental investigation of the use of an engine coolant exchange system for prewarming diesel engines before cold starting is discussed. This coolant exchange system involves connecting the coolant system of a fully warmed-up and running engine (e.g., a spark ignition engine) to that of the cold diesel to be started using hydraulic hoses with quick connect fittings and an auxiliary pump. The investigation was performed using a 4,3 liter V6 indirect injection diesel engine since this represents a difficult case for cold starting. The starting characteristics using the coolant exchange technique are compared to those using the production glow plug system, which includes a fuel heater and afterglow. It is shown that the coolant exchange system allows this engine to be started down to −26 °C, much colder than the −13°C limit for the production glow plug system.

This work investigates a combined internal combustion engine and solid oxide fuel cell (SOFC) hybrid powertrain for unmanned aerial vehicles (UAV). UAVs are increasingly used in large agriculture for crop management and water resource visual inspection, and in militarized applications, as they allow for safer, unmanned reconnaissance missions. The limited flight time of UAVs, as a result of the traditional lithium polymer batteries used for power, has restricted the widespread implementation of the UAV technology. A hybrid power train, utilizing energy dense liquid fuel, provides the capability of powering a UAV for longer duration missions. The hybrid power train consists of a small internal combustion engine that acts as a partial oxidation fuel reformer, simultaneously producing mechanical shaft power. The 0.3 in3 piston engine is a typical air cooled, glow engine utilizing a 60/40 percent (by volume) mixture of methanol and nitromethane, respectively.

Plastic underhood components often crack when fastened to mating components. The goal of this study is to determine what variables are most important with relation to this problem. To maximize the efficiency of testing, an L18 orthogonal array was used to structure the experiment. Experiments were conducted using a computer-controlled electric driven screwdriver and a manual torque wrench. Control factors were adjusted by using hardware as specified for each trial. The torque value at failure was recorded for all samples. The “larger the better” S/N equation was utilized for data analysis in this study. Optimizing the design and process was found to increase the S/N by 6.9dB when verified experimentally. Fastener washer thickness, joint fit-up, and screw setting speed contribute to the gain by 46%, 28%, and 27%, respectfully.

This paper outlines the development process of a radio frequency (RF) plasma ignitor and its application to internal combustion engines. The system features a high Q quarter-wave coaxial cavity resonator that serves as an electric field magnifier and as a discharge device. The preliminary characteristics of the cavity have been studied by the construction and operation of larger scaled devices. Testing has been performed using these devices in a testing apparatus operating under ambient conditions. Once an analysis of the large-scale device is complete, a smaller device, more inclined to interfacing with a standard engine, will be constructed and tested on a full scale engine. The final device is intended to operate in the 800-1500 MHz range.

The current popularity of the Sport Utility Vehicle (SUV) market has led to new developments aiming to increase product performance. Such vehicles pose a significant challenge as they must perform to a high standard over a large variety of road conditions. Previously, emphasis has been placed on off-road ability. However, SUVs are now seen as an alternative to conventional luxury cars, and hence are expected to perform similarly, but without significantly degrading off-road performance. The introduction of a roll control system can achieve body roll levels lower than a conventional sports saloon, whilst improving off-road ability by removing the compromises associated with conventional anti-roll bars. This paper investigates the characteristics of such a system by developing a computer simulation of the vehicle and the associated roll control scheme.

In this paper, a SI-HCCI combustion mode switch is investigated. The main challenge in switching is how to change the in-cylinder conditions (for example, A/F ratio, and internal EGR), which are different in SI and HCCI combustion. For mode switching without variations of BMEP and engine speed, we propose a new switching method. The concept of the proposed method is as follows: During switching between SI and HCCI, the A/F ratio and the internal EGR rate of each cylinder are controlled strictly by coordinating the variable valve systems and the throttle valve angle. In addition, the proposed method uses both an advance in spark timing and double fuel injection in order to stabilize combustion. From the experimental results, using a multi-cylinder test engine with variable valve systems and a direct fuel injection system, the variations of BMEP in switching were suppressed to 0.4 bar or less. Finally, the transitions of in-cylinder conditions during switching are examined.

In recent years, the utilization of dual-fuel combustion has gained popularity in order to improve engine efficiency and emissions. With its high knock resistance, methane allows operation in high compression diesel engines with lower risk of knocking. With the use of diesel fuel as an ignition source, it is possible to exploit the advantages of lean combustion without facing problems to provide the high amount of ignition energy necessary to burn methane under such operating conditions. Another advantage is the variety of sources from which the primary fuel can be obtained. In addition to fossil sources, methane can also be produced from biomass or electrical energy. As the rate of substitution of diesel by methane increases, the trade-off between nitrogen oxide and soot is mitigated. However, emissions of carbon monoxide and unburned methane increase.

Japanese accident statistics show that despite the decreasing trend of the overall traffic fatalities, more than 1,000 pedestrians are still killed annually in Japan. One way to develop further understanding of real-world pedestrian accidents is to reconstruct a variety of accident scenarios dynamically using computational models. Some of the past studies done by the authors' group have used a simplified vehicle model to investigate pedestrian lower limb injuries. However, loadings to the upper body also need to be reproduced to predict damage to the full body of a pedestrian. As a step toward this goal, this study aimed to develop a simplified vehicle model capable of reproducing pedestrian full-body kinematics and pelvis and lower limb injury measures. The simplified vehicle model was comprised of four parts: windshield, hood, bumper and lower part of the bumper. Several different models were developed using different combinations of geometric and stiffness representation.

A single-cylinder, open-chamber direct-injection (OCDI) diesel engine was converted to low compression ratio, spark-assisted operation. A modular construction cylinder head was built for the test work. The research work indicated that on a typical OCDI diesel engine, several spark plug locations are possible to produce successful ignition of a wide range of fuels. Performance tests were run with different compression and swirl ratio combinations. The best combination was found to be 12.2 compression ratio and 10 swirl ratio. The spark-assisted engine (CR 16:1) was performance tested with methanol and DF-2 plus 20% methanol emulsified fuel. The spark was always required with methanol, however, with emulsified fuel spark was desirable for starting and warming up periods. The investigation suggested the feasibility of economically developing multi-fuel spark-assisted diesel engines.

A simple rugged acoustic stall sensor which has an output proportional to angle of attack near wing stall has been evaluated on a Cessna 319 aircraft. A sensor position has been found on the wing where the sensor output is only slightly affected by engine power level, yaw angle, flap position and wing roughness. The NASA LRC General Aviation Simulator has been used to evaluate the acoustic sensor output as a control signal for active stall deterrent systems. It has been found that a simple control algorithm is sufficient for stall deterrence.

A side impact is one of the severest crash configurations among real-world accidents. In the US market, even though most vehicles have achieved top ratings in crash performance assessment programs in recent years, there has hardly been any sign of a decline in side-impact fatalities for the last few years, according to statistics retrieved from the National Highway Traffic Safety Administration’s Fatality Analysis Reporting System. In response to this trend, the Insurance Institute for Highway Safety (IIHS) is planning to introduce a new test protocol for side impact assessment. One of the points to be clarified in current side impact tests is whether the present side moving deformable barrier (MDB), which includes the barrier face and cart, faithfully reproduces a real-world car-to-car crash.

There are not only large amounts of energy, but also many different kinds of energy in manned spacecraft, which provide chance to optimize a thermal management system in the spacecraft. When water in atmosphere in pressured cabins was removed, waste heat in atmosphere was removed synchronously. Due to this phenomenon, a thermal management system, in which heat transfer in human zone and electrical equipment zone was considered together, was presented here. In the thermal management system, air loops in human zone and electrical equipments zone was reconstructed to decouple the waste heat and water removing processes, improve the heat exchange efficiency and make it possible to use waste heat produced by electrical equipments in other cabin with insufficient energy.

The drag reduction capability of a trailer underbody fairing is investigated using steady Reynolds-averaged Navier-Stokes simulations of a full-scale heavy vehicle traveling at highway speed within a crosswind. The flow field about the vehicle is modeled for two different fairing designs of varying length that yield reductions in the drag coefficient ranging from 0.013 to 0.042. Analysis of the trailer underbody flow field indicates that the fairings decrease the size of a recirculation zone that exists immediately downstream of the tractor drive wheels by providing a surface to which the separated underbody flow can reattach. A comparison of the pressure coefficients across the surface of the fairings demonstrates that the longer fairings produce greater pressure coefficients, hence resulting in a larger reduction in drag than the shorter fairings. One of the fairings is shown to outperform traditional trailer side skirts, which yield a reduction in the drag coefficient of 0.035.

This paper is a follow-up of the authors' earlier paper(1)* in which the development and evaluation of a mathematical model for turbulent flame propagation in the S.I. Engine had been described. The present paper gives a report of further studies regarding the general applicability of this model for S.I. engine combustion prediction. A simplified scheme has also been suggested to predict the pollutant emission by a correlation of the computed equilibrium mole fractions to the measured emission levels of ‘CO’ and ‘NOx’ in the exhaust. A wide variety of operating conditions has been considered and the model is applied in a simulation program to compute the combustion and exhaust emission characteristics for each operating condition. The predicted results, in general, are in conformity with the experimentally measured results reported in literature.

Automotive powertrain is diversifying. It is needed to adopt optimal powertrain considering CO2 reduction and convenience for the users. Diesel engines are beneficial from the points of view of thermal efficiency and reliability, but further emission reduction is needed. To reduce soot formation and late combustion, lowering equivalence ratio at the lift-off position, or fuel-rich spray core is thought to be effective. One approach to realize this is by enhancing air introduction from entrainment section (“(1)Increasing entrainment amount”), diluting the entire spray core. In addition to the conventional approach, this study discusses an alternative approach in which entrained air is selectively supplied to over-rich region to homogenize equivalence ratio at lift-off point, (“(2)Homogenization”). The investigations were performed by varying not only injection method like injection pressure or nozzle hole specification, but also fuel properties.

Biofuels for internal combustion engines have been explored worldwide to reduce fossil fuel usage and mitigate greenhouse gas emissions. Additionally, increased spark ignition (SI) engine part load efficiency has been demanded by recent emission legislation for the same purposes. Considering theses aspects, this study investigates the use of non-conventional valve timing strategies in a 0.35 L four valve single cylinder test engine operating with anhydrous ethanol. The engine was equipped with a fully variable valve train system enabling independent valve timing and lift control. Conventional spark ignition operation with throttle load control (tSI) was tested as baseline. A second valve strategy using dethrottling via early intake valve closure (EIVC) was tested to access the possible pumping loss reduction. Two other strategies, negative valve overlap (NVO) and exhaust rebreathing (ER), were investigated as hot residual gas trapping strategies using EIVC as dethrottling technique.

Diesel engines are facing increased competition from gasoline engines in the light-duty and small non-road segments, primarily due to the high relative cost of emissions control systems for lean-burn diesel engines. Advancements in gasoline engine technology have decreased the operating cost advantage of diesels and the relatively high initial-cost disadvantage is now too large to sustain a strong business position. SwRI has focused several years of research efforts toward enabling diesel engine combustion systems to operate at stoichiometric conditions, which allows the application of a low-cost three-way catalyst emission control system which has been well developed for gasoline spark-ignited engines. One of the main barriers of this combustion concept is the result of high smoke emissions from poor fuel/air mixing.