Engine Start-up Research Articles

Non-repeatability of the WLTP vehicle test results

The paper presents results of considerations on the repeatability of the passenger car test results obtained in the WLTP procedure on a chassis dynamometer. The research concerned the aspects of exhaust emissions and fuel consumption. Measurements were carried out in the WLTC test with a cold engine start and then in four WLTC (Worldwide harmonized Light vehicles Test Cycle) tests with a hot engine start. The following values were measured: average specific distance emissions of hydrocarbons, non-methane hydrocarbons, carbon monoxide, nitrogen oxides, particulate matter and carbon dioxide, specific distance particulate number, and operational fuel consumption. Thus, it was possible to assess the impact of the engine's thermal state at start-up on the test results and the nature of test results repeatability with the start-up of a hot engine. The repeatability of the test results was assessed based on the coefficient of variation obtained in the individual tests and the relationship of the maximum difference between measurement results values in the individual tests for a hot engine start. The obtained test results turned out to be very diverse for the considered parameters and indicated low repeatability. Values of carbon dioxide emissions and operational fuel consumption were definitely the least varied in individual hot engine start tests. The exhaust emission of particulate matter varied the most in individual test iterations. However, the specific distance particulate number was relatively similar between individual tests, less so than the exhaust emission of other pollutants. In the case of different engine thermal state at start-up, the emitted particulate number varied the most in the test results, while the emission of carbon dioxide and operational fuel consumption varied the least. The repeatability of executing the velocity process in WLTC tests at hot engine and cold engine start-up was also examined as processes determining exhaust emissions and fuel consumption. These tests were much more repeatable than the exhaust emission and fuel consumption.

Analysis of unstable combustion caused by the Gas–Liquid two-phase flow in small hypergolic propellant engines

Hypergolic bipropellant engines are extensively used in spacecraft operations. In these engines, the combustion reaction is initiated by the impinging jets of the oxidizer and fuel in the liquid phase. The most commonly used hypergolic fuels, hydrazine and monomethylhydrazine, as well as the oxidizer, nitrogen tetroxide, are all in liquid state under room temperature and atmospheric pressure conditions. However, as these engines are operated in a space vacuum, a portion of the propellant inevitably evaporates because of low-pressure boiling immediately after engine start-up. The mixing of gas with liquid propellant results in unstable combustion, and minimizing this effect is critical for the engine design. Particularly, preventing high-frequency combustion instability is essential as it can be detrimental to the engine. This paper presents a mechanism that activates high-frequency combustion instability, realized by analyzing the pressure within the combustion chamber during artificially induced unstable combustion. Furthermore, the methodology for establishing operational constraints based on the proposed mechanism is clarified, along with the method for collecting test data. The study findings provide important indicators for the design criteria of bipropellant engines, contributing to the diversification and complexity of space development programs.

A new real-time optimal energy management strategy for range extended electric vehicles considering battery degradation and engine start-up

A new real-time optimal energy management strategy for range extended electric vehicles considering battery degradation and engine start-up

Design and Research of a Certain Type of Automatic Alarm Equipment

Rapid detection of oxygen leaks in pipelines is crucial to prevent catastrophic accidents. This paper presents the design of an oxygen leakage detection and alarm instrument that converts ultrasonic signals, generated by gas escaping through small holes, into audible frequencies for headset use. This instrument is particularly suitable for ensuring the airtightness of oxygen supply systems for flight crews, engine startup supplemental oxygen systems, and four-station oxygen supply equipment. The design integrates ultrasonic principles, signal processing, computer control, and anti-jamming technologies to detect even minor leaks from a distance. The modular design includes components such as ultrasonic sensors, preamplifiers, filtering circuits, and microcontrollers, ensuring high detection sensitivity and reliability. The alarm system features light and sound alerts, enhancing maintenance efficiency and safety. This modern precision testing instrument significantly improves upon traditional leak detection methods like soapy water tests.

Jerusalem Artichoke as a Raw Material for Manufacturing Alternative Fuels for Gasoline Internal Combustion Engines

The Jerusalem artichoke (Helianthus tuberosus) is a high-yield crop, and a great source of fermentable sugars, which gives the plant the potential to be used as raw material for economical fuel alcohol production. In this article, the authors focus on the technological aspect of the biofuel manufacturing process and its properties. First, the fuel alcohol manufacturing process is described, afterwards assessing its characteristics such as kinematic viscosity, density and octane number. The amount of fuel alcohol obtained from 10 kg of biomass equals to 0.85 L. Afterwards, the mixtures of gasoline and obtained fuel alcohol are prepared and studied. Optimal alcohol and gasoline mixtures are determined to obtain biofuels with octane ratings of 92, 95 and 98. The kinematic viscosity of obtained mixtures does not differ significantly from its values for pure gasoline. The obtained biofuel mixture with 25% alcohol content yielded a decrease of sulfur content by 38%, an increase of vaporized fuel amount by 17.5% at 70 °C and by 10.5% at a temperature of 100 °C, which improves engine startup time and ensures its stable operation in comparison to pure gasoline. The alcohol obtained can be successfully used as a high-octane additive for gasolines.

Experimental study on the coupled flow field and thrust characteristics of tail cavity and jet

During the launch process of underwater vehicles, a tail cavity is formed at the bottom, which plays a crucial role in the engine ignition stage. The flow state within this tail cavity significantly impacts the engine's operational efficiency. Moreover, the evolution of the tail cavity and jet coupling, along with hydrodynamic characteristics, influences the motion attitude of the vehicle. This article delves into the effects of initial tail cavity length, Froude number, and pressure ratio on cavity morphology and hydrodynamic characteristics, utilizing water tunnel experiments to explore these dynamics at the vehicle's bottom. The experimental findings suggest that while the length of the initial tail cavity influences the jet's coupling mode, it does not significantly affect the cavity's ultimate morphological evolution. A larger initial cavity scale correlates with a lower initial pressure peak following nozzle activation; similarly, an increase in the Froude number leads to a decrease in the initial pressure peak. When the cavity morphology remains intact, the pressure pulsation amplitude and frequency are relatively low. In contrast, partially broken cavities and pulsating foam cavities differ in morphological structure and peak internal pressure oscillations, though their pressure pulsation frequencies are similar. During the initial phase of nozzle activation, the thrust produced by the nozzle plays a more significant role than the bottom thrust. Notably, in the initial phase of nozzle activation, the nozzle-generated thrust is more influential than the bottom thrust. The thrust pulsations from pulsating foam cavities are especially strong, with peak values surpassing the initial peak thrust. These insights offer a new insight on the dynamic behavior of underwater vehicles, crucial for refining engine startup strategies.

The Effect of Ethanol Fuel-Diluted Lubricants on the Friction of Oil Control Ring Conjunction: A Combined Analytical and Experimental Investigation

This paper presents an investigation of the frictional behaviour of three-piece piston oil control rings. A bespoke tribometer replicates the kinematics of the contact between a full oil control ring and the cylinder liner. The three-piece oil control ring is composed of two segments, separated by a waveform-type expander. The experimental results indicate the dominance of a mixed regime of lubrication throughout the stroke. This is particularly the case when the experiments are conducted at 80 °C, a typical engine sump temperature, when compared with those at 20 °C (a typical engine start-up temperature in the UK in the summer). A mixed hydrodynamic analytical model of the oil control ring–cylinder liner tribological interface is employed to apportion frictional contributions with their physical underlying mechanisms. Therefore, combined numerical and experimental investigations are extended to lubricant contamination/dilution by ethanol-based fuels. This study shows that the transition from E10 to E85 would have an insignificant effect on the friction generated in the oil control ring conjunction. This holistic approach, using a detailed predictive l mixed regime of lubrication model and a representative bespoke tribometry, has not hitherto been reported in the open literature.

КОМП'ЮТЕРНЕ МОДЕЛЮВАННЯ НЕСТАЦІОНАРНОГО ПРОЦЕСУ РОЗВИТКУ НАДЗВУКОВОГО ПЕРЕРОЗШИРЕНОГО СТРУМЕНЮ

Questions of numerical simulation of non-stationary process of the development of a supersonic overexpanded jet are considered. Unsteady Reynolds-averaged Navier-Stokes equations (URANS) of compressible flows, written in an arbitrary coordinate system, along with the Spalart-Allmaras one-equation differential turbulence model are applied. The calculations of non-stationary formation of an air cold supersonic jet during the blowing through a conical Laval nozzle (simulation of engine start-up) were made. The physical features of the shock and acoustic waves generation and propagation are discussed. In the stationary phase an overexpanded free supersonic turbulent jet is formed, which includes a Mach disc in its structure. The obtained results were compared with experimental data and calculations by other authors based on the ANSYS Fluent and FloEFD CFD tools.

Electromechanical and mechanical starter characteristics in the car engine start mode

When designing electric starter start systems for new automotive engines, it is necessary to coordinate the characteristics of the battery, starter and starting engine in order to determine the point of their joint operation under specified conditions. The starter is a converter of electrical energy into mechanical energy, that is, a matching link between the battery and the engine with its characteristic electromechanical and mechanical characteristics. This article discusses the issues of obtaining these characteristics for the conditions of low-temperature start-up of automobile engines. Keywords discharge current, voltage, resistance and volt-ampere characteristic of the battery, torque and frequency of rotation of the anchor, power and efficiency of the starter, electromechanical and mechanical characteristics of the starter

IM-TD3: A Reinforcement Learning Approach for Liquid Rocket Engine Start-Up Optimization

IM-TD3: A Reinforcement Learning Approach for Liquid Rocket Engine Start-Up Optimization

An assessment of the application of catalyst preheating prior to engine cold start to improve the filtration performance of CDPF on particulate emissions

The catalytic diesel particulate filter (CDPF) is an effective technology for reducing particle emissions. However, during engine startup, especially in cold start conditions, notable particle emissions are observed at the CDPF outlet. These emissions are attributed to combustion deterioration during startup and the low temperature of the aftertreatment catalyst. Addressing this challenge, this study investigated the effectiveness of rapidly preheating the diesel oxidation catalyst (DOC) and CDPF substrate temperatures before engine start to enhance particle removal during cold starts. Experimental results indicated that CDPF filtration efficiency during cold start was lower compared to hot start conditions, with a clean CDPF exhibiting very low efficiency due to minimal particle deposition. Substrate temperature preheating of either the DOC or CDPF was found to improve CDPF filtration efficiency for particles during cold start, albeit with a concurrent increase in emissions of particles smaller than 50 nm. Notably, a combination of a 250 °C DOC with a 22 °C CDPF yielded the most significant reduction in particle emissions, particularly for particles under 50 nm. Given that the DOC shares the same material composition as the CDPF but has a smaller volume that requires less energy for heating, preheating the DOC emerges as a more energy-efficient strategy. These findings underscore the need for more comprehensive studies on catalyst preheating to further the commercialization of technologies that effectively reduce cold start particle emissions, aligning with increasingly stringent future emission regulations.

Experimental study on flow control system of an electric pump-fed cycle for thrust control

An electric pump-fed cycle can enable the electrical control of pump revolutions and rapidly vary the propellant flow rate. This paper proposes the pump control method as a flow control system of an electric pump-fed cycle. In order to evaluate the applicability of the designed flow control system, the test equipment that simulates an electric pump-fed cycle was constructed, including the Li-ion battery power system and communication instruments. The designed PID controller demonstrated rapid flow stabilization and robustness compared to the system without a controller. Meanwhile, under the initial pressurized condition in the run tank that simulated an engine start-up sequence, the controller response delay occurred was more than 500 ms. In addition, the dynamic loads, such as the water hammer effects and overshoot, were identified. The start-up sequence of an EP cycle was adjusted to alleviate those issues. Consequently, the supply stabilizing time and overshoot were adjusted to 400 ms and 1.7 %, respectively. This study can be the first step in utilizing an electric pump-fed cycle for the thrust control technology in the upper stage of a mission.

Explore Electrical Insights: Evaluation of the Tektronix THS3024 Handheld Oscilloscope for Engine Analysis

The Tektronix THS3024 handheld oscilloscope is explored in this study by examining its efficiency in electrical measurements.In this study, the potential of the instrument is used to evaluate its performance in both unloaded and loaded engines. The THS3024 isequipped with 8 channels and allows the measurement of current and voltage. For this work, 6 channels were enabled due to the deltaconfiguration of the engine, providing 3 voltage channels and 3 current channels. Using a 60 volt supply, the channels were configuredto measure voltage and current parameters with appropriate attenuations. Through rigorous analysis, this study examines the behavior ofthe engine at startup and steady state, both with and without load. The plots showing the current waveforms during startup and steadystate with and without load highlight the ability of the device to automatically adjust its scale to capture even subtle variations. Thestudy acknowledges that while intrinsic factors have hindered the analysis of harmonics, the THS3024 still provides the ability to displayharmonic spectra. By examining the voltage and current response during engine startup, this study demonstrates the value of the THS3024in capturing essential transient characteristics and precise parameter changes. The negligible differences between loaded and unloadedengines underscore the reliability of the instrument in evaluating electrical behavior. This study thus demonstrates the potential of theTHS3024 for precise electrical measurements and promotes its applicability in electrical engineering research.

Effect of Operating Parameters on the Real-Time Torque Distribution of a Plug-In Electric Hybrid Vehicle

<div>This article presented a real-time torque distribution strategy for a single-shaft, plug-in hybrid electric vehicle (PHEV) and investigated the effect of multiple operating parameters by using three working conditions, namely, steady operating conditions, acceleration operating conditions, and brake operating conditions. The corresponding experiments were performed according to the earlier discussed three working conditions. The main conclusions of this study are given as follows: (1) Under steady operating conditions, the engine no longer offers torque to the motor for charging when the pedal degree is higher than 60%. (2) Under acceleration conditions, the engine startup is sensitive to the state of charge (SOC) decrement, maximum of 1%, and this decrement increases with an increase in the initial SOC. (3) Under brake operating conditions, the initial SOC may have a significant influence on the variation stability of motor torque, especially when the braking intensity is less than 0.1.</div>

Utilization of Non-verbal Communication in the Engine Room Training – Basic Research on Hand Signals among Monocultural Crew on Board

Accidents are likely to occur in an environment where work is done with teamwork by multiple crew members due to lack of communication, especially in a multicultural environment. Therefore, if there are internationally common maritime hand signals, it would contribute to reduction of human error among multicultural crews on board. As basic research on utilization of hand signals among multicultural crew on board, we invented several common hand signals. Furthermore, as a first step in an experiment to verify the effectiveness of hand signals during teamwork operation in engine room, we conducted the experiment in a mono-cultural environment through onboard training on a training ship. Our target task was practical onboard training for main engine start-up procedure in engine room because it required a lot of multitasking and teamwork. We studied the effectiveness and improvement of use of hand signals through questionnaires and interviews conducted with cadets and onboard instructors.

3D-printed zeolite 13X-Strontium chloride units as ammonia carriers

The selective catalytic reduction (SCR) system in automobiles using urea solution as a source of NH3 suffers from solid deposit problems in pipelines and poor efficiency during engine startup. Although direct use of high pressure NH3 is restricted due to safety concerns, which can be overcome by using solid sorbents as NH3 carrier. Strontium chloride (SrCl2) is considered the best sorbent due to its high sorption capacity; however, challenges are associated with the processing of stable engineering structures due to extraordinary volume expansion during the NH3 sorption. This study reports the fabrication of a novel structure consisting of a zeolite cage enclosing the SrCl2 pellet (SPZC) through extrusion-based 3D printing (Direct Ink Writing). The printed SPZC structure demonstrated steady sorption of NH3 for 10 consecutive cycles without significant uptake capacity and structural integrity loss. Furthermore, the structure exhibited improved sorption and desorption kinetics than pure SrCl2. The synergistic effect of zeolite as physisorbent and SrCl2 as chemisorbent in the novel composite structure enabled the low-pressure (<0.4 bar) and high-pressure (>0.4 bar) NH3 sorption, compared to pure SrCl2, which absorbed NH3 at pressures above 0.4 bar. Regeneration of SPZC composite sorbent under evacuation showed that 87.5% percent of NH3 was desorbed at 20 °C. Thus, the results demonstrate that the rationally designed novel SPZC structure offers safe and efficient storage of NH3 in the SCR system and other applications.

Data-driven predictive energy consumption minimization strategy for connected plug-in hybrid electric vehicles

Powertrain electrification incorporating advanced combustion-based dedicated hybrid engines (DHEs) is an effective and affordable approach to automotive energy saving. To explore the concealed fuel-saving potential of connected plug-in hybrid electric vehicles (CPHEVs) and manage engine dynamics, a data-driven predictive energy consumption minimization strategy (D-PECMS) is proposed in a hierarchical framework. The strategy relies on multi-source trip information provided by advanced driving assistance systems (ADAS) combined with maps and realizes power demand prediction by designing a multivariable long-term and short-term memory (M-LSTM) network. The upper level adopts dynamic programming (DP) to realize SOC planning, while the bottom layer utilizes D-PECMS to achieve computationally-efficient energy management with the engine combustion process being regulated in transient. This strategy is featured with predictive SOC tracking ability with less computational burden and look-ahead engine start-stop control. To ensure the credibility of validation, bench test data are used from a high-efficiency spark-induced compression ignition (SICI) engine to model the CPHEV, and the real-world driving scenarios are reconstructed based on real-time traffic data collected in China. The proposed D-PECMS strategy is tested through comprehensive experiments and compared against both the adaptive ECMS and offline DP. The results demonstrate that the proposed strategy effectively reduces fuel consumption by 3.1% and 13.2% in contrast to the adaptive ECMS and rule-based control respectively. Moreover, the D-PECMS strategy successfully avoids frequent engine operation mode switching as well as engine startup and shutdown.

Prediction of Burning Characteristics of Dihydroxyglyoxime Composite Propellant

An optimized engine start procedure is critical to the successful operation of a liquid rocket engine in launch vehicles. A solid propellant gas generator is widely adopted for the turbine starter during engine startup, and ammonium nitrate and ammonium perchlorate propellants are conventionally used for this purpose. However, these propellants have shortcomings such as high flame temperature, corrosive combustion residues, and low ignitability. In this study, a dihydroxyglyoxime (DHG)-based propellant was applied to turbine starters. The burning rate, characteristic velocity, and combustion temperature of the DHG propellant were evaluated using motor tests. The DHG-based propellant burned 3–11% slower in motor firing tests than that in strand burner tests, and an inversely proportional relationship was observed between the strand burn rate and the burning rate factor (ratio between motor burning rate measurement and strand burner prediction). The temperature sensitivity of the burning rate factor was found to be 0.23–0.24%/°C, and the pressure sensitivity of the characteristic velocity was 0.48–0.50%/MPa. These burning characteristics of the DHG-based propellant from static evaluations provide the evolution of the chamber pressure and the mass flow rate versus the time of the motor using internal ballistic analysis.

Non‐Planar Multiprocess Additive Manufacturing of Multifunctional Composites

AbstractMultiprocess additive manufacturing (AM) consists of integrating different 3D printing techniques to enable the fabrication of multifunctional parts, based on their geometry and material properties. The combination of fused filament fabrication (FFF) and direct ink writing (DIW) techniques, respectively involving thermoplastics and thermosetting polymers (or composites), often focuses on planar and small‐scale applications (i.e., few cm), with limited nozzle orientation freedom for the fabrication of complex parts. Many industries, such as the aerospace sector, could benefit from the AM of lightweight multifunctional parts. For instance, one of the key aircraft components, the abradable seal coating, is applied on gas turbine engines casing to increase engine efficiency and is mechanically abraded by the rotor blades during engine startup. Abradable coatings made of thermosetting polymer could be 3D‐printed using a multiprocess to obtain more functionalities. In this work, a non‐planar multiprocess AM approach involving FFF of a complex large sandwich panel structure with low material density and large‐scale DIW of an abradable thermosetting coating with controlled porosity for sound absorption potential, and better mechanical abradability than a commercial product, is presented. This multiprocess AM approach can be used to manufacture lightweight multifunctional structural parts for the automotive or aerospace industries.

Parametric evaluation of neat methanol combustion in a light-duty compression ignition engine

Methanol is currently considered a promising alternative fuel for energy de-fossilization due to its simplicity and adequacy for renewable production. This study investigates the feasibility of using neat methanol in high-efficiency compression ignition engines, with a focus on its potential to reduce CO2 emissions compared to conventional diesel. However, achieving efficient combustion of neat methanol in compression ignition engines presents challenges due to its low ignition capability, requiring higher compression ratios, intake temperatures, and pressures than diesel for autoignition. Furthermore, the high latent heat of vaporization contributes to significant cycle-to-cycle combustion variability. This work evaluates the combustion characteristics of neat methanol in a light-duty multi-cylinder compression ignition engine with a 19:1 compression ratio, examining its suitability for commercial applications. Performance indicators such as engine efficiency, fuel consumption, and engine-out pollutant emissions are assessed. The findings contribute to advancing research and implementation of methanol fuel as an energy source for internal combustion engine vehicles, addressing both the advantages of the fuel and the challenges that need to be overcome, particularly with respect to its low auto-ignition characteristics. Notably, despite methanol's lower energy density compared to diesel, the achieved combustion efficiency is comparable, with remarkable improvements in NOx and soot emissions trade-off.The study reveals that neat methanol combustion poses difficulties, especially at low loads, speeds, and during engine startup, due to its high ignition energy requirement and long ignition delay. Even with modifications such as increased compression ratio, and the addition of intake heaters and glow plugs, sustaining combustion at low load conditions remains a challenge. However, once the engine is warmed up, methanol combustion can be sustained at medium to high loads without additional heating accessories, although the use of such accessories improves combustion stability.