Engine Cycle Research Articles

Design and Development of Pneumatic Sheet Metal Cutting Machine

It is important to note that in today's industrial era, sheet metal is cut and bent into a variety of shapes to obtain better surface finish and flexibility in manufacturing processes. The use of modern techniques, such as pneumatic sheet cutting machines, has greatly improved the efficiency of sheet metal cutting and bending processes. This review focuses on the reliability, performance, and design simplification of pneumatic sheet cutting machines. Additionally, it examines the energy lost in the pneumatic cylinder while it imparts force on the cutting blade. The energy efficiency of pneumatic and compressed air systems is a critical aspect in the development of sustainable production. The objective of this cross-discipline review is to provide production and life cycle engineering researchers with an update on the state of the art in energy efficiency for pneumatic production and associated compressed air infrastructure.

Computational analysis of the scramjet mode of the RBCC inlet using micro vortex generators

Abstract A computational study of a three ramped dual duct Rocket Based Combined Cycle (RBCC) engine inlet at scramjet mode using different types of MVG (micro vortex generator) arrays were conducted. The definite geometry of engine inlet was operated at hypersonic speeds of Mach 5 and 7 to study the effect of the arrays of delta ramp (DR), rectangular vane (RRV) and ramp vane (RV) on the pressure recovery, exit Mach number, the mass flow rate and Shock wave Boundary Layer interaction (SWBLI). The study was performed considering same heights for all the configurations of MVG array and were positioned at the point of shock impingement on the ramp which caused the separation bubble. The computational analysis was done using k-omega model in Fluent Workbench of Ansys.

Design and Implementation of an Intelligent Metro Project Investment Decision Support System

The construction of subway projects involves tight engineering cycles, multiple technical challenges, and complex coordination among various stakeholders. Due to the influence of uncertain factors during the construction process, the investment in subway project construction exhibits non-linear changes over time. Investment decision-making is the process through which the investment entity determines its investment activities. For typical investment entities, project investment decision-making primarily entails analyzing and evaluating proposed engineering projects based on investigation, analysis, and argumentation, ultimately deciding whether to invest. With the widespread application of information technology (IT) across various fields, decision support systems (DSS) have emerged to enhance the decision-making capabilities of enterprise management. This article designs an intelligent subway project investment DSS, leveraging data mining (DM) technology to integrate DSS with a data warehouse (DW).

Theoretical thermal efficiencies of ideal, supercharged and gasoline engine cycles

This paper updated the perception of theoretical thermal efficiencies of reciprocating engine cycles by the analysis of six ideal cycles (Diesel, Joule-Brayton, Otto, Atkinson, Sabathe and Song). It was theoretically elucidated that more available energy remains in exhaust gas at higher load than at lower one, testifying that the exhaust waster energy recovery is more important at higher load than at lower one. A supercharged cycle was theoretically demonstrated to have lower thermal efficiency than its counterpart naturally-aspirated one, while supercharged engines had been always considered to have higher thermal efficiency. The thermal efficiencies of gasoline engines were first derived, testifying that a homogeneous spark-ignition gasoline engine at part-load has less thermal efficiency than its corresponding Otto cycle and can achieve a higher thermal efficiency by retarding (or advancing) inlet valve closing than by throttling intake flow.

Investigation into the Methodology and Implementation of Life Cycle Engineering under China's Carbon Reduction Target in the Process Industry

The industrial sector is the primary source of carbon emissions in China. In pursuit of meeting its carbon reduction targets, China aims to promote resource consumption sustainability, reduce energy consumption, and achieve carbon neutrality within its processing industries. An effective strategy to promote energy savings and carbon reduction throughout the life cycle of materials is by applying life cycle engineering technology. This strategy aims to attain an optimal solution for material performance, resource consumption, and environmental impact. In this study, five types of technologies were considered: raw material replacement, process reengineering, fuel replacement, energy recycling and reutilization, and material recycling and reutilization. The meaning, methodology, and development status of life cycle engineering technology abroad and domestically are discussed in detail. A multidimensional analysis of ecological design was conducted from the perspectives of resource and energy consumption, carbon emissions, product performance, and recycling of secondary resources in a manufacturing process. This coupled with an integrated method to analyze carbon emissions in the entire life cycle of a material process industry was applied to the nonferrous industry, as an example. The results provide effective ideas and solutions for achieving low or zero carbon emission production in the Chinese industry as recycled aluminum and primary aluminum based on advanced technologies had reduced resource consumption and emissions as compared to primary aluminum production.

Performance Analysis of Wave Rotor Combustor Integration into Baseline Engines: A Comparative Study of Pressure-Gain and Work Cycles

This study presents two concepts for integrating a wave rotor combustor (WRC) into a baseline engine: the wave rotor pressure-gain cycle (WRPGC) and the wave rotor work cycle (WRWC). Performance parameters were calculated under different thermodynamic cycles, and a comparative analysis of the thermodynamic cycles was conducted, considering both the ideal- and actual-loss conditions. Furthermore, the impact of the WRC precompression ratio, turbine inlet temperature, and fixed peak cycle temperature on the thermodynamic-cycle performance was investigated. The results indicate that embedding a WRC into a baseline engine with a compressor pressure ratio higher than 24.0 does not lead to an improvement in the thermal efficiency. However, under a baseline engine pressure ratio of 3.6, the actual-loss WRC cycle achieves efficiency improvements of 40.5% and 49.5% in the WRPGC and WRWC, respectively, compared to the baseline engine cycle. Increasing the wave rotor precompression ratio or the turbine inlet temperature ratio results in greater performance improvements for the WRWC compared to the WRPGC. When the peak cycle temperature of the wave rotor is fixed, there exists a narrow pressure ratio range wherein the WRPGC outperforms the WRWC. Therefore, the WRPGC is more suitable for embedment in baseline engines with lower pressure ratios.

Research on the Flow Mechanism of a High-Loading Biomimetic Low-Pressure Turbine Cascade

The biomimetic turbine has an excellent flow drag reduction ability and wide incidence adaptability, so it has the potential to achieve high efficiency within a wide working range of high-performance variable cycle engines. A biomimetic cascade that can broaden the effective working incidence angles was designed based on a high-loading low-pressure turbine cascade, and its flow mechanism and aerodynamic performance were studied using experimental and numerical methods under the incidences angle (i) of 0° to 15° and Reynolds number of 1.0 × 105. A series of counter rotating vortex pairs induced by the biomimetic cascade bring additional dissipation losses, but it accelerates the energy exchange between the boundary layer and mainstream, enhancing the dissipation of the pressure side leg of horseshoe vortex, and thus suppressing the flow separation and passage vortices. The undulating surface of biomimetic cascades can suppress the expansion of secondary flow in a spanwise direction in the end region, especially for large-scale separation under high incidence conditions. When i < 5°, the loss of biomimetic cascades is slightly higher than that of the original cascades, but the increase is only 0.5%; when i > 5°, the losses of biomimetic cascades are significantly reduced, with a maximum reduction of 70% at i = 15°.

Comparative analysis of European vertical landing reusable first stage concepts

AbstractReusable launch systems have the potential to significantly impact the space launch service market if both a high reliability and low refurbishment costs can be achieved. This study delves into the Vertical Takeoff and Vertical Landing (VTVL) methodology, as currently employed by SpaceX, and forms a segment of the ENTRAIN study by DLR. This broader study encompasses an examination of both Vertical Takeoff Horizontal Landing (VTHL) and VTVL reusable first stages, exploring their performance across high-level design parameters. This manuscript’s primary objective is to assess the quantitative impact of high-level design factors on launch vehicle performance, particularly in relation to the development of a future European reusable launch system featuring a VTVL first stage. For a two-stage vehicle with a payload performance of 7.5t into GTO, the effect of varying propellant combinations, staging velocities and engine cycles are assessed. The study encompasses an iterative, multidisciplinary analysis and sizing process for ten different configurations. Each design iteration not only entails a structural design analysis but also includes optimization of the ascent and descent trajectories. Finally, the developed vehicle concepts are compared to derive quantitative insights into the trade-offs associated with key design choices.

Practical low-temperature gasoline combustion for very high efficiency off-road, medium- and heavy-duty engines

Low-temperature gasoline combustion (LTGC) with additive-mixing fuel injection (AMFI) is a new combustion strategy that has been demonstrated to deliver 9%–25% better brake thermal efficiency than similar-sized market-leading diesel engines over the operating map. Moreover, the LTGC-AMFI engine shows near-zero smoke, and NOx emissions are 4–100 times lower than those of a diesel, sufficiently low that no aftertreatment, or only passive NOx aftertreatment, would be sufficient (diesel exhaust fluid is not required). LTGC-AMFI combustion is based on kinetically controlled compression ignition of a dilute charge with a variable amount of low-to-moderate fuel stratification. Fast combustion control is provided by adding minute amounts of an ignition-enhancing additive into the fuel each engine cycle to control its reactivity. This strategy was used to operate a medium-duty (MD) LTGC-AMFI engine at loads from idle to 16.3 bar BMEP and speeds from 600 to 2400 rpm with regular E10 gasoline, which covers nearly the entire operating map of a typical MD engine. Turbine-out temperatures were sufficient for an oxidation catalyst to control hydrocarbon and CO emissions. Autonomie simulations over the GEM ARB Transient and the GEM 55 mph Cruise driving cycles for class-6 trucks using this technology showed fuel economies of 8.1 and 11.4 mpg-gasoline-equivalent, respectively, corresponding to 18.6% and 13.4% improvements over a similar-size diesel engine. Engine-out NOx emissions were 0.024 and 0.01 g/bhp-h, respectively, well below current U.S. emission standards. These results show that switching from diesel to LTGC-AMFI engines would greatly reduce greenhouse gas (GHG) emissions for off-road, MD and HD applications, which will continue to rely on combustion engines because electrification is not practical in the foreseeable future. With their reduced fuel consumption, the lower cost of gasoline compared to diesel fuel, and much lower aftertreatment costs, LTGC-AMFI engines also offer a significantly lower total cost of ownership.

Variations on the models of Carnot irreversible thermomechanical engine

Abstract The JETC Conference held in Salerno (June 12–17, 2023) was the opportunity to honor the two centuries anniversary of the booklet publication of Sadi Carnot. The paper reports on a selective review summarizing the evolution of the ideas and concepts proposed by Carnot. We consider mainly: a. The Carnot cycle relative to thermomechanical engine, b. The concept of efficiency (Carnot efficiency), c. The forms of energy (thermal energy or heat, Q, and mechanical energy or work, W), d. The concept of entropy, rediscovered and completed by Clausius. We show the importance of the energy conversion irreversibilities that started to be considered more recently by two methods, namely, the ratio method and the entropy production method. The second approach provides more significant results from a global point of view, also with more local modeling (cycle process modeling). Some examples are given that illustrate the proposal: Carnot cycle in endo-irreversible or exo-reversible configuration, Chambadal modeling, Curzon–Ahlborn modeling. More generally, the modeling is done in the frame of FTT (Finite Time Thermodynamics), FST (Finite Speed Thermodynamics), or FDOT (Finite physical Dimensions Optimal Thermodynamics). Preliminary conclusions and perspectives are proposed.

Embedded but overlooked values: Ethical aspects of absolute environmental sustainability assessments

AbstractCurrently used sharing principles (grandfathering and final consumption expenditure) do not align with the purpose of Absolute Environmental Sustainability Assessments (AESAs)—enabling all to meet basic needs within the planetary limits. This discrepancy, though niche within life cycle engineering, demands attention due to the integration of the sharing principles in the widely adopted Science Based Targets initiative, embraced by 4000+ companies, representing over a third of the global economy. This paper suggests operationalizing sufficientarianism as a fair sharing principle for AESAs guaranteeing a minimum threshold of well‐being for all. The theory of human needs is highlighted to distinguish luxuries from necessities. This is vital when assigning shares to products/companies, as there's no room for luxuries (products for someone which cause others to fall short), given the extremely limited individual safe operating space, regardless of the sharing approach. This paper argues that sufficientarian‐based sharing principles must overlook historically skewed material welfare distributions to ensure no one falls below the minimum threshold. It underscores the need for an interdisciplinary approach to sharing principles, acknowledging and discussing diverse value perspectives on equal grounds. The focus is to inform and discuss the development of new sharing principles, which introduces initial steps toward a sufficientarian‐based approach. The paper concludes that recognizing embedded values is paramount in sharing principle development. Failing to do so risks letting quantifiable metrics dictate the values integrated into AESAs without open discourse.

Simulation-Based Thermal Fatigue Validation Test Development for Exhaust Manifold

Abstract Exhaust manifolds in diesel engines undergo continuous thermal cycle loading of varying thermal cycles with different mean, amplitude, and rate of temperature change created by application duty cycles. This makes analysis and testing of the exhaust manifold to meet the thermal mechanical fatigue life expectation of different applications challenging. In this paper, a simulation-based product development approach, which uses application duty cycles, simulation models of different capabilities, including three-dimensional Finite element simulation model, one-dimensional (1D) physis-based damage model to develop an abusive thermal cycle engine test for validating exhaust manifold, is presented.

Comprehensive Flow Path Design Method for the Adaptive Cycle Engine Considering the Coupling Relation of Multiple Components

Abstract The adaptive cycle engine (ACE) has multiple coupled components on the same spool and complex bypass system, which makes it have more complex intercomponent coupling relation and hard to coordinate in the flow path design. In this study, the coupling relation of the ACE components and the component reference conditions are analyzed and determined, a multicomponent collaborative optimization design method is proposed to enable the quantitative evaluation of flow path design solutions. In this method, two optimization strategies are presented based on the different priorities of the intercomponent size coupling parameters, the intercomponent aerodynamic coupling parameter and the component performance in the optimization problem. ACE flow path solutions for various feasible design speed combinations are generated automatically considering the component performance and intercomponent coupling relation. According to an ACE flow path design case study, the design physical rotational speeds of low-pressure spool (NL,d) and high-pressure spool (NH,d) should be 7000 to 7600 r/min and 10,000 to 15,000 r/min, respectively. At NH,d = 12,000 r/min and NL,d = 7200 r/min, the high-pressure compression components and the fan components could be designed with the lowest aerodynamic load, respectively. NH,d is the key factor affecting the axial length of ACE. This method can be applied to other gas power plant designs.

Experimental and numerical study on flow mixing and combustion characteristics of a novel multibypass integrated combustor

The integrated design of multibypass augmented/ramjet combustors can reduce the weight of turbine-based combined cycle (TBCC) engines and improve the thrust-to-weight ratio, but low-resistance mixing and efficient stable combustion of multiple airflows over short distances are necessary prerequisites. In this study, a novel structure for a TBCC multibypass integrated augmented/ramjet combustor is proposed. The influence of the inlet aerodynamic parameters on the flow field, mixing efficiency, flow loss, and combustion performance of the combustor under different working modes was obtained via experimental and numerical methods. The experimental results show that the outlet mixing efficiency is greater than 86% in the double-bypass mode (DB-mode). While the triple-bypass mode (TB-mode) has a larger decrease, the total pressure loss is slightly reduced (by approximately 0.5%). The opening of the ram duct has a significant impact on the flow field, resulting in different rules for the influence of the inlet temperature on the outlet mixing efficiency: in the DB-mode, the mixing efficiency decreases with increasing inlet temperature, while the rule is completely opposite after entering the TB-mode. Because the dominant role of the two mixing zones in the flow field changes with the velocity, the inlet velocity has a significant impact on the mixing efficiency in the flow direction. The combustion simulation results show that the combustion efficiency in the DB-mode is almost always above 90% and the high-temperature zone is mainly concentrated downstream of the integrated strut. The radial temperature gradient increases and the combustion efficiency decreases in the TB-mode.

The influence of residual gas on ozone-assisted combustion in an HCCI reciprocating engine

This work is an investigation on the influence of both residual gas and ozone on the combustion process in an HCCI engine fuelled with iso-octane/air/ozone mixtures and on how ozone reacts with residual gases. It is well known that ozone releases oxygen atoms mainly through the O3+M⇄O2+O+M reaction and this may lead to an improvement of the engine combustion. Nevertheless, the chemical interaction between ozone and the species in the residual gas has not yet been investigated in the literature. CFD simulations of a closed-valve engine cycle have been carried out by using an axisymmetric domain. The model has been validated against experimental data and a parametric analysis has been carried out to assess different compositions and amounts of residual gases on the engine performance. The results show that ozone during compression enables Low-Temperature Combustion, with a small amount of heat released before the occurrence of auto-ignition. The combustion is faster and advanced with a reduction of UHCs and an increase of NOx. The results show that the influence of ozone is more effective as the mass of residual gases increases. With an ozone concentration of 35 ppm at IVC, the gross work per cycle increases by 2.52%, 3.58% and 5.7%, compared to the case without ozone, with 0%, 5% and 10% by mass of residual gases, respectively. It can be concluded that ozone is more beneficial for cases where combustion is slower due to the higher amount of residual gases.

Combustion characteristics optimization and thermal efficiency enhancement by stratified charge of hydrogen direct injection for argon power cycle hydrogen engine

Argon power cycle hydrogen engine is a novel approach to increasing the thermal efficiency of hydrogen engines while achieving zero CO2 emissions. This paper presents a combination of experiments and simulations used to examine the effects of hydrogen direct injection on the combustion characteristics and thermal efficiency of argon power cycle engines. The results of the study indicate that, in comparison to port hydrogen injection, hydrogen direct injection produces a delay of CA50 exceeding 12.36°CA at an engine speed of 1000 r/min. This delay optimizes combustion and diminishes knock intensity to below 0.1 MPa by creating a stratified mixture, which in turn decelerates the combustion rate. Through adjusting hydrogen direct injection timing and incorporating super lean combustion, a maximum gross indicated thermal efficiency of 53.72% is achieved. By optimizing the first injection timing, the second injection timing, and the second injection ratio, dual hydrogen direct injection can significantly suppress knock and increase thermal efficiency compared with original single hydrogen injection conditions.

Quantum software engineering and quantum software development lifecycle: a survey

AbstractQuantum software engineering is advancing in the domain of quantum computing research and application, yet the documentation is scattered. The slow transition from Von-Neumann based computation systems to quantum systems, and conserving the fundamental computing principles in software development and software engineering helps in enrichment of quantum software development. The evolution of quantum computing over the past years shows a shift in the domain of classical computation to quantum computation in the years to come. Future applications such as, quantum AI and quantum machine learning will benefit from quantum software engineering. This survey collects and explores the various documentations in the domain of quantum systems and quantum software engineering. The survey provides an in-depth exploration of quantum programming languages, which is combined with explanations of quantum computing’s fundamentals. The review also goes in-depth about quantum software engineering and quantum software life cycle development, outlining the quantum software reuse methodology that is introduced in the quantum software lifecycle development domain.

A Comprehensive Analysis of Hydrogen–Gasoline Blends in SI Engine Performance and Emissions

This study investigates the influence of adding hydrogen as an additive to gasoline in a four-stroke engine, utilizing comprehensive thermodynamic comparative analysis conducted with self-developed engine model. This research aims to assess the performance, emissions, and efficiency of the engine when using gasoline–hydrogen blends, and to provide insights into the potential benefits of this approach. First, the engine performance and emissions under different hydrogen blending levels were examined. A range of different air/fuel ratios (rich to lean) and varying percentages of hydrogen were considered. This systematic variation allowed for a detailed evaluation of the influence of hydrogen content on combustion efficiency, power output, and emissions characteristics. The analysis results included key parameters such as indicated specific fuel consumption and mean effective pressure. Additionally, the study focused on the range prediction of nitrogen oxide (NOx) emissions, which are a critical environmental concern associated with internal combustion engines. The analysis of pressure and temperature profiles throughout the engine cycle shed light on the combustion characteristics and efficiency improvements associated with hydrogen addition. In terms of emissions, the study projected that all emissions were reduced except NOx, which is highly dependent on hydrogen percentage, and might be reduced in some cases, but with the higher temperatures and pressures associated with hydrogen addition, in most cases, there is actually a NOx increase, especially at higher engine loads.

Efficiency Evaluation of Using Water-Fuel Emulsion as Fuel for Automobiles

Road transport is the main consumer of petroleum fuel as well as a source of toxic substances. Therefore, reducing fuel consumption and emissions of harmful substances in road transport is one of the most important problems facing modern engine construction. One of the ways to solve this problem is through the use of mixed fuels, including water-fuel emulsions. Water-fuel emulsion is a promising alternative fuel that could fulfill such requests in that it can improve the combustion efficiency of internal combustion engines and reduce harmful exhaust emissions, especially nitrogen oxide (NOx) and particulate matter (PM). Up to now, there have been many studies on water-fuel emulsions, especially on performance, emissions and micro-explosion phenomena. Using water-fuel emulsion as fuel for ships worldwide was studied and applied to the 80-ies of the last century, but using it for automobiles is still limited by the emulsion stability and economic difficulties to calibrate engine parameters for a new fuel. This article provides an overview of the mechanism and performance operating cycle of internal combustion engines using water-fuel emulsions and the efficiency, economy, and environmental friendliness of this fuel type for automobiles. Hence, conclusions are drawn about the possibility and effectiveness of using emulsions as fuel for automobiles, especially under conditions in Vietnam.

Deterministic engines extending Helmholtz thermodynamics

Helmholtz formalism provides a tantalizing interpretation of classical thermodynamics, based on time integrals of purely mechanical quantities and without need of statistical description. Here we extend this approach to include heat flux and pressure at the walls to enable it to describe actual thermodynamic transformations, such as isothermal compressions and expansions. The presence of hard walls, which gives rise to non zero pressure, is justified by means of the virial theorem, while the heat fluxes are introduced as quasi-static limits of suitably thermostatted Hamiltonians. Particular attention is paid to generalizing the minimalist cases of the harmonic oscillator and elastic bouncer, which afford clear physical interpretations. With such extensions, a complete picture of thermodynamics emerges, amenable to phase transitions and cyclic deterministic transformations, which produce mechanical work from heat, like the Carnot cycle.