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Cavitation plays a significant role in high pressure diesel injectors. However, cavitation is difficult to measure under realistic conditions. X-ray phase contrast imaging has been used in the past to study the internal geometry of fuel injectors and the structure of diesel sprays. In this paper we extend the technique to make in-situ measurements of cavitation inside unmodified diesel injectors at pressures of up to 1200 bar through the steel nozzle wall. A cerium contrast agent was added to a diesel surrogate, and the changes in x-ray intensity caused by changes in the fluid density due to cavitation were measured. Without the need to modify the injector for optical access, realistic injection and ambient pressures can be obtained and the effects of realistic nozzle geometries can be investigated. A range of single and multi-hole injectors were studied, both sharp-edged and hydro-ground. Cavitation was observed to increase with higher rail pressures.

The study of spray-wall interaction is of great importance to understand the dynamics that occur during fuel impingement onto the chamber wall or piston surfaces in internal combustion engines. It is found that the maximum spreading length of an impinged droplet can provide a quantitative estimation of heat transfer and energy transformation for spray-wall interaction. Furthermore, it influences the air-fuel mixing and hydrocarbon and particle emissions at combusting conditions. In this paper, an analytical model of a single diesel droplet impinging on the wall with different inclined angles (α) is developed in terms of βm (dimensionless maximum spreading length, the ratio of maximum spreading length to initial droplet diameter) to understand the detailed impinging dynamic process.

This paper presents a method for reliability assessment of the electric grid with distributed generation providing support to the system. Evaluation of customer controlled distributed generation contribution is done for two cases; the first case analyses distributed generation wherein generation units export power to the grid. The second case analyses onsite generation wherein units handle loads at individual customer sites, thus relieving grid congestion. Reliability parameters for the distributed generation systems were obtained from data collected from existing systems that have been in operation for an extended period of time. Calculations are performed on the IEEE-Reliability Test System. The state duration sampling approach using Monte Carlo simulations is employed to evaluate the ability of the system to meet demand requirements. The impact of distributed generation on the utility controlled grid as well as on individual customer reliability is evaluated.

Given the importance of the fuel-injection process on the combustion and emissions performance of gasoline direct injected engines, there has been significant recent interest in understanding the fluid dynamics within the injector, particularly around the needle and through the nozzles. The pressure losses and transients that occur in the flow passages above the needle are also of interest. Simulations of these injectors typically use the nominal design geometry, which does not always match the production geometry. Computed tomography (CT) using x-ray and neutron sources can be used to obtain the real geometry from production injectors, but there are trade-offs in using these techniques. X-ray CT provides high resolution, but cannot penetrate through the thicker parts of the injector. Neutron CT has excellent penetrating power but lower resolution.

The dense spray region in the near-field of diesel fuel injection remains an enigma. This region is difficult to interrogate with light in the visible range and difficult to model due to the rapid interaction between liquid and gas. In particular, modeling strategies that rely on Lagrangian particle tracking of droplets have struggled in this area. To better represent the strong interaction between phases, Eulerian modeling has proven particularly useful. Models built on the concept of surface area density are advantageous where primary and secondary atomization have not yet produced droplets, but rather form more complicated liquid structures. Surface area density, a more general concept than Lagrangian droplets, naturally represents liquid structures, no matter how complex. These surface area density models, however, have not been directly experimentally validated in the past due to the inability of optical methods to elucidate such a quantity.

The atmospheres of US Navy Submarines are unique closed environments in which sailors both live and work for extended periods. Although this atmosphere is continuously monitored with a real-time, mass spectrometer-based Central Atmosphere Monitoring System (CAMS), the ability to measure trace constituents is limited. The identity, concentrations and distributions of trace constituents have been studied more exhaustively, in some cases for as long as the duration of a patrol, using conventional active air sampling methods such as passivated stainless steel canisters and solid sorbent tubes. The results from these studies indicate that trace constituents are generally present at concentrations well below levels that would present health concerns. However, these studies also show that there is a fairly wide variation in such levels over time, operational conditions, submarine and class of submarine.

This paper proposes a new design procedure and energy absorption models that improve material and absorber geometry selection for given service conditions. Design diagrams are constructed that show the energy absorption of uniaxial and trapezoidal absorber geometries as a function of foam density and strain rate for closed cell polyethylene packaging foam. Design constraints including load spreading, buckling, creep, and material costs are addressed. Energy absorption models are developed that generate design data incorporating load spreading, impacting object geometry, polymer deformation and gas compression that agrees within ten percent of measured values.

The salient features of modern gasoline direct injection include cavitation, flash boiling, and plume/plume interaction, depending on the operating conditions. These complex phenomena make the prediction of the spray behavior particularly difficult. The present investigation combines mass-based experimental diagnostics with an advanced, in-house modeling capability in order to provide a multi-faceted study of the Engine Combustion Network’s Spray G injector. First, x-ray tomography is used to distinguish the actual injector geometry from the nominal geometry used in past works. The actual geometry is used as the basis of multidimensional CFD simulations which are compared to x-ray radiography measurements for validation under cold conditions. The influence of nozzle diameter and corner radius are of particular interest. Next, the model is used to simulate flash-boiling conditions, in order to understand how the cold flow behavior corresponds to flashing performance.

The objectives of this paper are to describe an undergraduate project recently carried out at the University of Massachusetts on a vapor cycle automotive power system, to discuss some of the educational aspects of the project, and to briefly describe some of the results obtained. The problem posed to the seven undergraduate students involved in the project concerned certain aspects of the preliminary design and development of a small vapor powered powerplant for an automotive application. The technical design criteria given at the initial stages of the project was quite general: be competitive in size, weight, and power with conventional automotive IC engines. A socially significant constraint was also given: the powerplant should have low pollutant emission characteristics. The student's interpretation and application of this constraint to the engineering design studies clearly influenced the technical decisions they made.

The various methods available for proximity measuring are described and evaluated, resulting in the choice of radar as the best method available. Radar does have its drawbacks, however, and its major liability is the production of a possible health hazard in the form of microwave radiation. Limits imposed by the U.S. government are presented and compared to values obtained from a proposed system.

Mesh generation is frequently one of the most labor-intensive aspects of in-cylinder engine simulation with computational fluid dynamics (CFD). This expense makes parameter studies, such like engine geometry, valve timing or injection timing, a particularly challenging endeavor. The present paper introduces a CFD approach for the simulation of the in-cylinder processes of an internal combustion engine that minimizes user-required meshing effort and can handle almost unlimited boundary motion. The adaptation is fully automated and avoids the use of target meshes and global solution remapping. The intention of the approach is to use CFD for numerous parameter variations involving combustion system variabilities. Therefore, an open source base is chosen to avoid limitations of individual simulations due to a finite number of commercial licenses. The approach is used here for the simulation of a modern direct injection spark igniton (DISI) engine.

A method for evaluating a driver's response in a nighttime crash scenario is offered. A pedestrian can be said to be within the headlight beam when the line representing the shape of a headlight beam equals the pedestrian approach vector. This method is based upon headlight beam mapping and the illumination necessary for drivers to recognize non-illuminated objects on an unlit road at night. The most notable information gained through this research is to be able to correlate headlight illumination with driver response distances. From 25 nighttime driver response distance experiments, information was gathered from many of the original authors. This information includes position left or right, headlight type, lighting, movement of the object or pedestrian, and the position (standing, slumped or laying).

Outdoor objective evaluations form an important part of both tire and vehicle design process since they validate the design parameters through actual tests and can provide insight into the functional performances associated with the vehicle. Even with the industry focused towards developing simulation models, their need cannot be completely eliminated as they form the basis for approving the performance predictions of any newly developed model. An objective test was conducted to measure the ABS performance as part of validation of a tire simulation design tool. A sample vehicle and a set of tires were used to perform the tests- on a road with known profile. These specific vehicle and tire sets were selected due to the availability of the vehicle parameters, tire parameters and the ABS control logic. A test matrix was generated based on the validation requirements.