Type Of Combustion Engine Research Articles

A Review on Flame Stabilization Technologies for UAV Engine Micro-Meso Scale Combustors: Progress and Challenges

Unmanned aerial vehicles (UAV)s have unique requirements that demand engines with high power-to-weight ratios, fuel efficiency, and reliability. As such, combustion engines used in UAVs are specialized to meet these requirements. There are several types of combustion engines used in UAVs, including reciprocating engines, turbine engines, and Wankel engines. Recent advancements in engine design, such as the use of ceramic materials and microscale combustion, have the potential to enhance engine performance and durability. This article explores the potential use of combustion-based engines, particularly microjet engines, as an alternative to electrically powered unmanned aerial vehicle (UAV) systems. It provides a review of recent developments in UAV engines and micro combustors, as well as studies on flame stabilization techniques aimed at enhancing engine performance. Heat recirculation methods have been proposed to minimize heat loss to the combustor walls. It has been demonstrated that employing both bluff-body stabilization and heat recirculation methods in narrow channels can significantly improve combustion efficiency. The combination of flame stabilization and heat recirculation methods has been observed to significantly improve the performance of micro and mesoscale combustors. As a result, these technologies hold great promise for enhancing the performance of UAV engines.

Modeling of pollutant emissions from the turbine engine of the main propulsion of a vessel in operating conditions

The intensification of environmental protection measures is being implemented in all economic and industrial activities. The goal of reducing harmful emissions from various types of combustion engines used in different applications is being pursued dynamically. The introduced changes concern the values of harmful emission limits and the methods of measuring or assessing their emissions. There are solutions for propulsion systems, such as turbine engines used on ships, where there is a need for constant monitoring of operational and environmental parameters during the operation of the vessels. Continuous measurement of harmful emission values contained in exhaust gases during the operation of these systems allows for an assessment of their impact on the environment. However, due to the costs of measuring equipment and limitations associated with its use, alternative methods are being sought to evaluate pollution emissions resulting from the operation of turbine engines. One possibility is to assess the emission characteristics of the propulsion system in emission tests under conditions of its actual operation. Based on this, by introducing basic mathematical tools, it is possible to determine the values of emissions of individual pollutants during the propulsion system operation in actual conditions. These actions are presented in this paper.

Evaluation on 14C emission patterns of various PWR types in South Korea and effectiveness of inventory reduction driving (IRD)

In this research, we investigated to examine the emission characteristics of radioactive carbon emitted from three types of pressurized water reactors. And we examined the possibility of 14C inventory reduction by changing operating conditions of one of the nuclear power plants. Results showed that 14C inventory in the reactor coolant system (RCS) remained constant before the overhaul (O/H) period and more than 90% of the radioactive carbon was found to be organic form. At spent fuel pool, the 14C chemical form of the liquid phase during the O/H period was also dominated by the inorganic (14CO2) form as in the case of the RCS due to the acid oxidized state. We applied gas stripper (G/S) and VCT purge operation to perform the 14C inventory reduction operation for Combustion Engineering type. In the case of gas strippers, approximately 50% of 14C inventory was reduced in the first year and then about 97% in the second year. Unlike our expectations, in case of VCT purge operation, 14C reduction effect was not showed greatly.

A design method of selecting gear ratios in manual transmissions of modern passenger cars

The objective of this paper is to present an algorithm of gear ratio calculation in the manual transmissions of modern passenger cars. The paper presents all the necessary coefficients and formulas and thoroughly explains their influence on particular features of the vehicle, which are closely connected with its expected exploitation. These formulas result both from physical relationships and the performed analysis of vehicle dynamics, fuel economy, ergonomics and road characteristics. Every type of combustion engine, SI naturally aspirated, SI turbocharged or CI turbocharged, can be considered as vehicle propulsion. Particular emphasis is placed on a new method of gear spacing, which enables the simple and precise adjustment of intermediate gears. To quantitatively assess the dynamics and fuel economy of a specific construction, formulas for drawing the full throttle power characteristic and the characteristic of specific fuel consumption are provided. Moreover, a short and effective formula for calculating maximum vehicle speed has been developed. At the end of the work, there is a calculation example, which is an integral part of the article, showing the presented method on a particular vehicle.

Experiment designing in operating investigations of subassembly of the marine energy systems

To choose the receive locations of diagnostic signals, reliability and preliminary investigations were applied. The functional systems and the most unreliable subassemblies were determined. The studies were conducted for the auxiliary marine engines with the same rated speed and fueled with same distillation and residual fuels. In the article a choice of the ship's object, which has a significant impact on reliability, operating costs and the functions performed, is presented. Reliability, economic and risk of exploitation investigations were carried out, which allowed selecting the facility with the highest failure, costs of adverse events and threat to the natural environment. The research covered the objects of a ship owner operating mainly bulk cargo vessels for mass transport and their essential assemblies - combustion engines.In order to obtain a reasonable amount of information on the state of the examined combustion engine, the following experimental planning methods were used: experiment type, essential elements, location of measurement sensors, measured quantities, test conditions, measurement frequencies, measurement data analysis and inference methods, etc.The reliability indicators and preliminary diagnostic tests were used to select the diagnostic signal reception points. Functional systems and the most unreliable subassemblies were defined in this way. The tests were carried out for auxiliary marine engines with the same rotational speed and fueled by distillation and residual fuels. The tests were conducted for several types of combustion engines.

Analysis of errors of commission for a CE type plant with the advanced control room in the full power condition

This study analyzes errors of commission (EOCs) committed by operators of an Combustion Engineering (CE) type plant with the advanced control room during full power operation, by using the Commission Errors Search and Assessment (CESA) and Misdiagnosis Tree Analysis (MDTA) methods. The contribution of EOCs to plant safety is significant in the digital control room of the reference plant, where the cognitive behavior of an operator plays more important role in the control than in the analog control room. In this study, the CESA and MDTA methods are applied to the identification and quantification of EOCs, respectively. This study chooses eight initiating events that account for approximately 90% of the total core damage frequency (CDF) in the full power condition of the reference plant. As a result of applying the CESA method, twelve EOCs are identified along with the accident sequence groups. Then, the probabilities of those EOCs are quantified through the MDTA method. Finally, this study discusses the effect of EOCs on system failure probability, as well as the necessity of considering EOCs in the probabilistic safety assessment (PSA) of the reference plant.

Pressure drop-flow rate curves for single-phase steam in Combustion Engineering type steam generator U-tubes during severe accidents

Characteristic pressure drop-flow rate curves are generated for all row numbers of the OPR1000 steam generators (SGs), representative of Combustion Engineering (CE) type SGs featuring square bend U-tubes. The pressure drop-flow rate curves are applicable to severe accident natural circulations of single-phase superheated steam during high pressure station blackout sequences with failed auxiliary feedwater and dry secondary side which are closely related to the thermally induced steam generator tube rupture event. The pressure drop-flow rate curves which determine the recirculation rate through the SG tubes are dependent on the tube bundle geometry and hydraulic diameter of the tubes. The larger CE type SGs have greater variation of tube length and height as a function of row number with forward flow of steam favored in the longer and taller high row number tubes and reverse flow favored in the short low row number tubes. Friction loss, natural convection heat transfer coefficients, and temperature differentials from the primary to secondary side are dominant parameters affecting the recirculation rate. The need for correlation development for natural convection heat transfer coefficients for external flow over tube bundles currently not modeled in system codes is discussed.

Performance evaluation of Zircaloy reflector for pressurized water reactors

This paper presents detailed analyses of a pressurized water reactor with a new reflector design using zirconium metal. The optimization of the reflector design has been performed using a two-dimensional fuel assembly reflector model. The three-dimensional core calculation results with the optimized reflector were compared against those with the existing water reflector and iron reflector. The high scattering cross section of zirconium enhances neutron reflections from the reflector to the core, increasing the peripheral assembly powers. From the analysis based on the equilibrium core, it was noted that the cycle length can be extended, and the pin peaks can be decreased when using zirconium reflector. The analysis has been performed for the optimized power reactor 1000 core with combustion engineering type fuel assemblies using the CASMO-4E/SIMULATE-3 (Studsvik Scandpower, Inc., Waltham, MA, USA) code system and SERPENT (VTT Technical Research Centre of Finland, Vuorimiehentie 3, 02150 Espoo, Finland) code, with ENDF/B-VI data. Copyright © 2015 John Wiley & Sons, Ltd.

Performance optimization of Stirling engines

The search for an engine cycle with high efficiency, multi-sources of energy and less pollution has led to reconsideration of the Stirling cycle. Several engine prototypes were designed but their performances remain relatively weak when compared with other types of combustion engines. In order to increase their performances and analyze their operations, a numerical simulation model taking into account thermal losses has been developed and used, in this paper, to optimize the engine performance. This model has been tested using the experimental data obtained from the General Motor GPU-3 Stirling engine prototype. A good correlation between experimental data and model prediction has been found. The model has also been used to investigate the influence of geometrical and physical parameters on the Stirling engine performance and to determine the optimal parameters for an acceptable operational gas pressure.

Modeling and Control of Free-Piston Generator

This paper describes modeling and control of a Free-Piston Generator (FPG). A FPG is a special type of combustion engine representing a new approach concerning the conversion of the chemical energy of hydrocarbon fuel into electrical energy. Unlike conventional engines, this type of engine does not use a crankshaft, and generates electric energy directly by a linear movement of pistons.

Modeling and Control of Linear Combustion Engine

This paper describes modeling and control of a Linear Combustion Engine (LCE). A LCE is a special type of combustion engine representing a new approach concerning the conversion of the chemical energy of hydrocarbon fuel into electrical energy. Unlike conventional engines, this type of engine does not use a crankshaft, and generates electric energy directly by a linear movement of pistons.

A quantitative approach to modeling the information flow of diagnosis tasks in nuclear power plants

This paper proposes an approach to quantify the information flow of diagnosis tasks in nuclear power plants . This paper presents a method to quantify cognitive information flows in diagnosis tasks, integrating a stage model (a qualitative approach) with information theory (a quantitative approach). The focus of the method is on (i) developing a stage model to describe information flow for diagnosis tasks, and (ii) quantifying the information flow. We develop an information flow model which consists of four stages: perception, identification, diagnosis, and planning. According to the knowledge it contains, five categories of the state of information are defined. Then, the information flow of the model is quantified using Conant's model. Finally, we apply this method to seven diagnosis tasks described in diagnosis procedure of the emergency operating procedure for reference plant A (combustion engineering type) and investigate the applicability of this approach.

A robust flow sensor for high pressure automotive applications

Abstract In this paper, a micromachined mass flow sensor mounted on a high pressure stable substrate is presented to measure on board the different injection quantities needed in modern direct injection (DI) systems for optimum performance of the engine. To detect the injection end/begin as well as the injection rate as precisely and fast as possible, the sensor is completely integrated into the nozzle body close to the injection holes for the first time. The thermal measurement principle is chosen, as gasoline and diesel fuel quantities can be detected and therefore, the use of this present flow sensor is not restricted to one of these different types of combustion engines. The fabrication process of the molybdenum (Mo) thin film sensors on an LTC (low temperature co-fired) ceramic chip is described. Additionally, FEM simulations concerning the velocity profile in the injection nozzle are performed and the electrical heating power of the hot film anemometer at different overheat ratios is analytically calculated. Finally, the injection rate measurements up to 60 MPa (600 bar) with the nozzle-integrated thin film sensor are presented and their additional information compared to signals gained from an injection amount indicator (EMI), which is part of the high-pressure hydraulic test bench, are discussed.

Determination of the minimal number and optimal sensor location in a nuclear system with fixed incore detectors

The determination of the minimal number of sensors and the optimal sensor location in a nuclear system with fixed incore detectors, which is represented by a linear stochastic distributed parameter system, was studied in this work. The partial differential equation representing nuclear reactor dynamics was approximated to the finite dimensional ordinary differential equation by the modal expansion. A scalar measure of the covariance matrix error in the optimal filter was minimized with respect to the sensor locations. The necessary conditions for optimal sensor location were derived using the matrix minimum principle, thus making the calculations computationally more attractive. The locations of sensors were guessed initially through sensitivity analysis to reach solutions of the optimal location quickly. A method to determine the minimum number of sensors is suggested based on the observability and admissible error bound. Several numerical simulations are performed to determine the minimal number and optimal sensor location for a one-dimensional slab reactor and a two-dimensional ABB Combustion Engineering type reactor with fixed incore detectors. Through the simulations the possibility of practical implementation and the rapid convergence of the algorithm are verified.

Fuel control systems for hydrogen-fueled automotive combustion engines—a prognosis

The state of the art in the field of hydrogen-fueled combustion engines was investigated and conclusions were drawn concerning the future development of fuel control systems for automotive engines using hydrogen as fuel. Assuming the use of modern microprocessor technology together with recently developed linear digital actuators and solenoid operated injectors, basic concepts for fuel control systems were proposed for three mainly used types of combustion engines: gas turbine engine for aircraft propulsion, spark ignition engine for cars and compression ignition engine for vehicles and off-highway equipment. These concepts are based on a liquid hydrogen on-board storage system which seems to be the most feasible for use in the near future.