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Technical Paper

Zero Gravity and Life Support Systems — Friends or Foes?

Manned spacecraft life suport systems must operate in a zero gravity environment. Lack of the “pull” of gravity affects heat and mass transfer, fluid transport, phase change, and chemical and electrochemical processes. This paper covers new concepts necessary for humidity control, evaporative coolers, distillation units, and similar equipment required for spacecraft life support. Specific applications used on the Space Shuttle and in development for advanced regenerative systems are discussed, including how they work, how they are tested on earth, and how much, if at all, the weightless environment penalizes the designs.
Technical Paper

Zero Hand Coding Approach for Controller Development

As the demand for more complex system development and the ever-increasing requirement for improvement in software productivity, the need for graphical programming or Zero-Hand Coding for automatic generation of controller software becomes highly desirable. The graphical programming must not be limited to the algorithm development which consists of the application modules but must be extended to the microcontroller platform, which include the middleware (i.e. operating system, I/O device drivers) and hardware. Automatic code generation is very important for programming the complex microcontroller internal parameters and registers. The combined software tool chain is to generate the final target specific executable code. This approach is very beneficial for system development, reduction of the development cycle and bridges the gap between control and software engineers reducing time, effort and cost of the production software.
Technical Paper

Zero Prototype Approach in the Development of a Plastic Automotive Component

In the developement process, the engineer is required to design, validate and deliver the components for manufacturing, in an as short as possible lead time. For that, the engineer may use some available tools to save not only time, but also cost. This work presents a zero prototype approach applyied to a plastic component, whose main accomplishment was the decreasing of lead time development due to the intensive use of virtual tools (CAD/CAE). As a result, the product was delivered in a short time, with no need of building physical prototypes, thus reducing development cost.
Technical Paper

Zero Resistance Technology (ZRT)

Delphi's Zero Resistance Technology (ZRT) is a revolutionary new product/process that enables the reduction of mass and volume from a traditional wiring assembly. ZRT is defined as a minimal (zero) resistance change over time. The ZRT product is an electrical/electronic connection system which provides a viable solution for high density and limited space wiring applications. The ZRT process is a semi-automated wiring harness manufacturing system with flexibility to produce harnesses to the customer demand.
Technical Paper

Zero Wear Analysis of an Injector Coupling

The coupling is an integral part of the Cummins CELECT electronically controlled injector. Excessive wear was observed on early designs of the coupling and coupling bore. The coupling wear was caused by a high stress concentration and excessive side loading of the coupling as it slid against the coupling bore. The zero wear theory was used to develop a coupling design where the maximum wear depth does not exceed half the peak to peak surface finish (zero wear) over the life of the engine. The side load exerted on the coupling was compared with the calculated contact pressure for zero wear. The undesirable effects of a square edge stress concentration are discussed in the zero wear model. The physical effects of the sharp edge and chamfered coupling edge are reported, but not analyzed in this paper. Three different coupling designs were investigated by applying the zero wear concept.
Technical Paper

Zero-Delay Light-Off - A New Cold-Start Concept with a Latent Heat Storage Integrated into a Catalyst Substrate

This study aims at a new concept for a fast catalyst light-off in combining a latent heat storage with a catalyst. The arrangement of a latent heat storage device into the exhaust system offers significant benefits for the catalyst light-off. Different arrangements have been examined. The first arrangement, called the sequential arrangement, comprises a latent heat storage device and a subsequent catalyst. This offers a significantly faster heat up of the catalyst compared to the standard arrangement. By that emissions during the cold start phase can be significantly reduced. The setup of the latent heat storage device is designed for a high heat transfer between storage material and the exhaust gas. A second integrated arrangement of a latent heat storage and a catalyst into one common substrate has also been set up and investigated. The main advantage of this arrangement is that the catalyst itself is kept on its operation temperature during the engine off time.
Journal Article

Zero-Dimensional Modeling of Combustion and Heat Release Rate in DI Diesel Engines

Zero-dimensional heat release rate models have the advantage of being both easy to handle and computationally efficient. In addition, they are capable of predicting the effects of important engine parameters on the combustion process. In this study, a zero-dimensional combustion model based on physical and chemical sub-models for local processes like injection, spray formation, ignition and combustion is presented. In terms of injection simulation, the presented model accounts for a phenomenological nozzle flow model considering the nozzle passage inlet configuration and an approach for modeling the characteristics of the Diesel spray and consequently the mixing process. A formulation for modeling the effects of intake swirl flow pattern, squish flow and injection characteristics on the in-cylinder turbulent kinetic energy is presented and compared with the CFD simulation results.
Journal Article

Zero-Dimensional Simulation of Diesel Engine Combustion and Emissions Based on CMC Model and Skeletal Reaction Mechanism

A zero-dimensional code is developed to simulate turbulent spray combustion and NOx and soot emission in direct injection diesel engines. The code consists of two major parts; mixing calculation for the probability density function (PDF) based on the multi-zone model by Hiroyasu et al., (1983) and the flame structure by the conditional moment closure (CMC) model (Klimenko & Bilger, 1999). The skeletal mechanism of n-heptane is employed with the elementary reaction steps for heat release and the NOx chemistry in GRI 3.0. The spray model accounts for evaporation and mixing based on momentum balance of the spray zones, while the CMC model incorporates the conditional flame structures with one fuel group or flame structure for each injection. The spatially integrated density-weighted PDF, F(η), is defined to represent inhomogeneous mixture distribution in the cylinder. The one-equation soot model is employed for prediction of the soot emission.
Technical Paper

Zero-Dimensional Soot Modeling

A zero-dimension model of spray development and particulate emissions for direct-injection combustion was developed. The model describes the major characteristics of the injection plume including: spray angle, liquid penetration, lift-off length, and temperatures of regions within the spray. The model also predicts particulate mass output over a span of combustion cycles, as well as a particulate mass-history over a single combustion event. The model was developed by applying established conceptual models for direct injection combustion to numerical relations, to develop a mathematical description of events. The model was developed in a Matlab Simulink environment to promote modularity and ease of use.
Technical Paper

Zero-Dimensional Spark Ignition Combustion Modeling - A Comparison of Different Approaches

Internal combustion engines development with increased complexity due to CO2 reduction and emissions regulation, while reducing costs and duration of development projects, makes numerical simulation essential. 1D engine simulation software response for the gas exchange process is sufficiently accurate and quick. However, combustion simulation by Wiebe function is poorly predictive. The objective of this paper is to compare different approaches for 0D Spark Ignition (SI) modeling. Versions of Eddy Burn Up, Fractal and Flame Surface Density (FSD) models have been coded into GT-POWER platform, which connects thermodynamics, gas exchange and combustion sub-models. An initial flame kernel is imposed and then, the flame front propagates spherically in the combustion chamber. Flame surface is tabulated as a function of piston position and flame radius. The modeling of key features of SI combustion such as laminar flame speed and thickness and turbulence was common.
Technical Paper

Zero-G Simulation using Neutral Buoyancy

For human beings who have been reared on the earth with its 1 G gravitational field, the condition of weightlessness is a world with which we are unfamiliar. Even if the layout and equipment configuration of a spacecraft designed to compensate for operation under Zero-G conditions, there are some things which are not effective under actual weightless conditions. In the design of a manned spacecraft, it is necessary to accumulate design data on human performance in a weightless condition, then to undertake design evaluations and verification under weightless conditions. In this paper, testing for the purpose of evaluating the effectiveness of Zero-G simulation using neutral buoyancy, conducted first of all in Japan, and recommendations on the equipment and Facilities required to conduct such simulations, are described.
Technical Paper

Zero-G Water Selection Separator: A Performance Tradeoff

This paper presents a trade-off study to select a water separator system for a 3-man, 140-day, zero-g mission. Included is a summary of feasible concepts, a compilation of data on existing hardware, and a comparison of the performance characteristics of each with respect to the overall system. Six approaches to zero-g water separation were considered and are discussed: hydrophobic/hydrophilic screens; integrated condenser-water separators; centrifugal separators; cellular sponges; vortex separators; and elbow separators. Some of these techniques have high-performance characteristics with regard to water removal efficiency. However, when reduced to hardware, these same techniques may not integrate well with the overall system. The system selected was the integrated condenser-water-separator. This system requires no power, has no moving parts, and has a very small envelope.
Technical Paper

Zero-Gravity Testing of a Waste Management System

This paper describes the testing of a waste management system designed and fabricated for use in a space vehicle. The system provides for the collection and inactivation of urine, feces, emergency diarrheal disorders, vomitus, and debris; the volumetric determination of each micturition; and onboard storage of the inactivated wastes within the waste management system compartment. The zero-gravity test program conducted in a KC-135 aircraft provided the primary verification of the performance of the waste collection and urine volume determination functions prior to actual space flight. The test hardware simulated the actual system to a high degree of fidelity with respect to operational characteristics of the airflow required in collection, mechanical functions and system pressure differentials, in order to minimize simulation errors.
Technical Paper

Zero-Offset in Transducer Output

Zero-offset in transducer output during airbag noise testing is often observed, but mostly ignored due to the lack of understanding of its causes and implications. In the field of high-g acceleration measurement, this phenomenon is well documented, and is referred to as zeroshift. Zero-offset occurs when a component in the measurement chain is exposed to some unexpected inputs which the component has not been designed to handle. These unexpected inputs can be mechanical, electrical, or optical. How the transducer reacts to such inputs and the amount of zero-offset produced depends on the sensing mechanism, material used, and the design of the component itself. This paper explores the causes of zero-offset from a general perspective, covering the entire measurement chain. Although much of the information and discussions are based on data obtained from acceleration measurement systems, the findings are applicable to other transducer types, such as pressure and acoustic measurements.
Technical Paper

Zero-Venting, Regenerable, Lightweight Heat Rejection for EVA Suits

Future space exploration missions will require a lightweight spacesuit that expends no consumables. This paper describes the design and performance of a prototype heat rejection system that weighs less than current systems and vents zero water. The system uses regenerable LiCl/water absorption cooling. Absorption cooling boosts the heat absorbed from the crew member to a high temperature for rejection to space from a compact, non-venting radiator. The system is regenerated by heating to 100°C for two hours. The system provides refrigeration at 17°C and rejects heat at temperatures greater than 50°C. The overall cooling capacity is over 100 W-hr/kg.
Technical Paper

Zero-Waste PVD Cadmium for High Strength Steels

In spite of environmental issues related to cadmium and its electroplating process, electroplated cadmium is still extensively used in the aerospace and defense sectors. This trend is likely to continue especially for high strength steels because cadmium provides the best known corrosion and embrittlement protection for this application. Consequently, the environmental concerns related to the cadmium electroplating have been addressed using an alternative Zero-waste Physical Vapor Deposition (Z-PVD). This method does not use liquids, it recycles cadmium in situ, and is free of hydrogen embrittlement. The Z-PVD process is now in commercial production for the aerospace fasteners. The quality of the coatings has been at least equal to that of the electroplated cadmium.
Technical Paper

Zero-dimensional Model and Pressure Data Analysis of a Variable-Displacement Lubricating Vane Pump

A zero-dimensional dynamic model was developed in the Matlab/Simulink® environment to predict the behaviour of a variable-displacement lubricating vane pump for internal combustion engine applications. Based on the geometric and kinematic characteristics of the pump, the model allows predictions of the pressure evolution in each chamber of the pump and in the delivery piping, by employing an integrative-derivative approach. Simulation results were compared with experimental data of pressure transducers, which were fitted along the periphery of the pump case and in the delivery channel. The analysis of the experimental data shows that the pressure dynamics, which is experienced by the transducers, is in some cases quite different from the pressure dynamics in the pump chambers and produces pressure peaks which are not actually present in the original signal. The pressure transducers output was then also modelled in order to properly compare simulation results and experimental data.
Technical Paper

Zeroshift Automated Manual Transmission (AMT)

Zeroshift technology allows a manual transmission to change gear in zero seconds. The Zeroshift Automated Manual Transmission (AMT) is easy to manufacture and allows a cost effective alternative to the traditional torque converter based automatic transmission. Zeroshift offers potential fuel economy improvements from driveline efficiency and the best possible vehicle acceleration. Compared to an existing AMT, Zeroshift offers an uninterrupted torque path from the engine to vehicle which allows for a seamless gearshift. This seminal paper provides an introduction to the technology together with test data from a demonstrator vehicle.
Technical Paper

Zeroshift. A Seamless Automated Manual Transmission (AMT)With No Torque Interrupt

Zeroshift technology allows a manual transmission to change gear in zero time. The Zeroshift automated manual transmission (AMT) is easy to manufacture and allows a cost effective alternative to the traditional torque converter based automatic transmission. Zeroshift offers potential fuel economy improvements from driveline efficiency and the best possible vehicle acceleration. Compared to an existing AMT, Zeroshift offers an uninterrupted torque path from the engine to vehicle which allows for a seamless gearshift. This paper provides an introduction to the technology together with test data from a demonstrator vehicle.