Complete Engine Research Articles

Modeling of Hydrogen Combustion from a 0D/1D Analysis to Complete 3D-CFD Engine Simulations

Hydrogen and its unique properties pose major challenges to the development of innovative combustion engines, while it represents a viable alternative when it is based on renewable energy sources. The present paper deals with the holistic approach of hydrogen combustion modeling from a 0D/1D reactor evaluation with Cantera up to complete engine simulations in the 3D-CFD tool QuickSim. The obtained results are referenced to the current literature and calibrated with experimental data. In particular, the engine simulations are validated against measurements of a single-cylinder research engine, which was specifically adapted for lean hydrogen operation and equipped with port fuel injection and a passive pre-chamber system. Special attention is hereby given to the influence of different engine loads and varying lambda operation. The focus of this work is the complementary numerical investigation of the hydrogen flame speed and its self-ignition resistance under the consideration of various reaction mechanisms. A detailed transfer from laminar propagation under laboratory conditions to turbulent flame development within the single-cylinder engine is hereby carried out. It is found that the relatively simple reaction kinetics of hydrogen can lead to acceptable results for all mechanisms, but there are particular effects with regard to the engine behavior. The laminar flame speed and induction time vary greatly with the inner cylinder conditions and significantly affect the entire engine’s operation. The 3D-CFD environment offers the opportunity to analyze the interactions between mixture formation and combustion progress, which are indispensable to evaluate advanced operating strategies and optimize the performance and efficiency, as well as the reliability, of the engine.

Lipidation Engineering in Daptomycin Biosynthesis.

Lipopeptides are an important family of natural products, some of which are clinically used as antibiotics to treat multidrug-resistant pathogens. Although the lipid moieties play a crucial role in balancing antibacterial activity and hemolytic toxicity, modifying the lipid moieties has been challenging due to the complexity of the lipidation process in lipopeptide biosynthesis. Here, we show that the lipid profile can be altered by engineering both secondary and primary metabolisms, using daptomycin as an example. First, swapping the fatty acyl AMP ligase (FAAL) gene dptF with foreign FAAL homologs improved the fatty acyl specificity of the lipidation process for decanoic acid. Then, the introduction of Mycobacterium type I fatty acid synthase operon (MvFAS-Ib/MvAcpS) and Cryptosporidium thioesterase (CpTEII) enriched the fatty acid pool with decanoic acid in Streptomyces roseosporus. The engineered fatty acid metabolism eliminates the need for external decanoic acid supplementation by enabling S. roseosporus to biosynthesize decanoic acid. By complete engineering of the lipidation process, we achieved, for the first time, high-purity, natural production of daptomycin. The lipidation engineering approach we demonstrate here lays the foundation for the lipidation control in lipopeptide biosynthesis.

A comprehensive propulsion system analysis: an integrated approach utilising engine simulation and free-running model experiments

Regulations concerning the environmental impact and energy efficiency of ships are becoming increasingly stringent. To meet these demanding criteria, new technologies are actively being developed to achieve emission reductions while maintaining efficient fuel energy conversion into propulsion power. However, the propulsion system behaviour in a dynamic environment of the actual sea is highly nonlinear and complex, and a profound understanding of the mutual interactions is still lacking. This paper proposes an integrated approach for comprehensive propulsion system analysis. The key feature of this technique is the utilisation of an intelligent propeller drive controlled by a marine diesel engine simulator (MDES) to drive the free-running model of a ship, providing real-like behaviour of the engine model in real-time in response to actual measured values. The core of the MDES consists of a continuous cycle-mean value dynamic engine model supplemented with a detailed combustion cycle evaluation. The developed fast calculation algorithm of crank-angle resolved thermodynamic equations of the gas state in the engine cylinder enables the complete engine model to be integrated into the real-time environment of a physical model ship. Thus, the propulsion system's performance can be analysed under conditions that closely mimic those of the actual sea environment.

Diesel Engine Turbocharger Monitoring by Processing Accelerometric Signals through Empirical Mode Decomposition and Independent Component Analysis

In this study, a method for the monitoring of internal combustion engine operation by vibration signals is proposed. The work falls within the context of the increasingly stringent standards relating to the environmental impact of engines and the development of monitoring and control techniques to ensure increased engine performance as well as fuel saving and reduction of pollutant emissions. Experimentation was performed on a turbocharged light-duty compression ignition direct-injection engine. Two monoaxial accelerometers were installed on the engine compressor case, the speed of which has been demonstrated to be closely related to the engine operation. Vibration measurements of the engine compressor case have been processed by combining the Empirical Mode Decomposition technique with Independent Component Analysis and Short Time Fourier Transform to indirectly estimate the turbocharger speed. The obtained traces have been compared to the direct turbocharger velocity measures during the stationary running of the engine (speed and load conditions varied in the complete engine’s range of operation). The results point out the potentiality of the methodology in algorithms devoted to identifying modifications of the combustion development regarding regular operation via indirect turbocharger speed monitoring.

A cyclical marker system enables indefinite series of oligonucleotide-directed gene editing in Chlamydomonas reinhardtii.

CRISPR/Cas9 gene editing in the model green alga Chlamydomonas reinhardtii relies on the use of selective marker genes to enrich for non-selectable target mutations. This becomes challenging when many sequential modifications are required in a single cell line, as useful markers are limited. Here, we demonstrate a cyclical selection process which only requires a single marker gene to identify an almost infinite sequential series of CRISPR-based target gene modifications. We used the NIA1 (Nit1, NR; nitrate reductase) gene as the selectable marker in this study. In the forward stage of the cycle, a stop codon was engineered into the NIA1 gene at the CRISPR target location. Cells retaining the wild-type NIA1 gene were killed by chlorate, while NIA1 knockout mutants survived. In the reverse phase of the cycle, the stop codon engineered into the NIA1 gene during the forward phase was edited back to the wild-type sequence. Using nitrate as the sole nitrogen source, only the reverted wild-type cells survived. By using CRISPR to specifically deactivate and reactivate the NIA1 gene, a marker system was established that flipped back and forth between chlorate- and auxotrophic (nitrate)-based selection. This provided a scarless cyclical marker system that enabled an indefinite series of CRISPR edits in other, non-selectable genes. We demonstrate that this 'Sequential CRISPR via Recycling Endogenous Auxotrophic Markers (SCREAM)' technology enables an essentially limitless series of genetic modifications to be introduced into a single cell lineage of C. reinhardtii in a fast and efficient manner to complete complex genetic engineering.

Logic-driven, simulation-based risk engineering to ensure the sustainability of productive processes even with data scarcity

Designing and operating production systems and keeping them up to date at the speed of innovation to meet competition, consumer trends and sustainability requirements is a challenging task. The problem becomes even more challenging when the production system is highly uncertain and data-poor. This complexity is increasingly recognised, as is the value that risk engineering can bring to the design, operation, maintenance and upgrading of production systems to avoid compromising their viability and ensure their continued efficiency.The manuscript is guided by this challenge and has a twofold objective. First, it analyses and explains the importance of adopting a logic-driven and simulation-based risk engineering approach to support decision-making. This objective is achieved by going to the root of the methodological constructs that characterise the methodologies available in the literature and by highlighting the main limitations. Second, it applies the HoRAM method to the use case of food banks to verify its suitability. The use case of food banks was chosen because it is characterised by more and unusual uncertainties compared to conventional production systems (such as uneven labour and raw material availability).The main contributions of this research are as follows. First, it provides a critical analysis of currently available risk assessment methodologies. It highlights the weaknesses and explains the implications of these weaknesses for decision support. Second, it concerns the development of a complete risk engineering process, offering an approach that goes beyond conventional risk assessment approaches that stop at the identification of the critical elements associated with the problem at hand. It explains the importance of closing the risk analysis loop by quantitatively verifying the efficiency of the identified mitigation solutions, thus moving from risk assessment to risk engineering.The results suggest that the proposed approach is suitable for supporting complex decision-making processes characterised by high uncertainty and data scarcity. Furthermore, due to the logic-driven nature of the proposed approach, non-experts can be involved and contribute to the analysis and engineering of risks. This allows to increase the situational awareness of decision makers and consequently their efficiency in making complex decisions.

Unique Operating Conditions Analysis of Turboshaft Engines Based on Nonlinear Integrated Model

The unique mission of the helicopter compared to the fixed-wing aircraft introduces challenges to the aerodynamic stability of the turboshaft engine. Thus, the assessment of the availability of stability margin for special operating conditions in the envelope of this equipment is required to guarantee flight safety. In this paper, a rapid nonlinear complete engine method is developed to investigate the effect of helicopter ground-effect operation and high-altitude hovering on aerodynamic stability by considering factors including inlet distortion and component matching. Research indicated that the most dangerous point of stability margin in a unique section of the flight envelope is high altitude hovering, with about a 16.7% reduction in available stability margin compared to standard ground test conditions. This paper also investigates the effects of typical helicopter ground effects on a turboshaft engine and shows that the stability margin will be reduced by a maximum of 1.43% in hovering if the influence of ground effects in the flight envelope is not considered in the design.

Optimizing cluster spacing in multistage hydraulically fractured shale gas wells: balancing fracture interference and stress shadow impact

Horizontal drilling and multistage hydraulic fracturing have seen widespread application in shale formations during the past decade, leading to significant economic productivity gains through the creation of extensive fracture surfaces. The determination of the ideal cluster spacing in shale gas wells is contingent upon the unique geological and formation characteristics. Generally, reducing the spacing between clusters has the potential to augment gas recovery, albeit at the expense of higher drilling and completion costs, as well as the influence of stress shadows on fracture propagation. This study introduces an integrated methodology designed to explore the impact of cluster interference on well performance. Commencing with a fracture propagation model accommodating stress shadow effects for an equivalent slurry volume injection, analytical rate transient analysis (RTA) was amalgamated with reservoir numerical simulation to compute the effective fracture surface area (Aca.) for hydrocarbon production. The correlation between the effective fracture surface area determined by RTA and the actual stimulated fracture area (Aca.) derived from numerical simulations was established in relation to cluster spacing. The findings of this research reveal that wells featuring a greater number of stages and tighter cluster spacing tend to exhibit elevated cluster interference, resulting in a lower effective-to-actual fracture surface area ratio and heightened stress shadow effects impeding fracture propagation. A cluster spacing of 33 feet with six clusters per stage emerges as the optimal choice at formation permeability of 0.00005 md that decreased to 18 ft at formation permeability of 0.00001 md. ACe either stabilizes or decreases above the optimal value, suggesting that more clusters would not have a major impact on increasing the effective stimulated area. Allowing 20% interference, regardless of the permeability of the formation, maximized cumulative production while preventing thief zones and excessive cluster interference. The insights gained from this study will serve as a valuable resource for completion and reservoir engineers, enabling them to fine-tune cluster spacing to maximize well revenue in the dynamic landscape of shale gas extraction.

New methodology for the characterization of 3D model reconstructions to meet conditions of input data and requirements of downstream application

AbstractIn the field of 3D model reconstruction, manifold methods have been developed that derive CAD models from 3D scan data. Opposed to classical CAD modelling, where surface and solid modelling exist, a further diversification of modelling techniques is observed, caused by different methods to build up the geometry. This research introduces a new classification, the so-called Level of Complexities. It can be applied to the complete Reverse Engineering process chain and lays the foundation for further research on how to match requirements arising from all process steps and downstream applications.

A Comprehensive Review of Screen Plugging during Openhole Sand Control Completions Installation: Causes, Consequences, and Best Practices

Summary In openhole completions, screens are one of the very common equipment used to control production of solids. Screens could get plugged during installation in case of improper wellbore fluid conditioning and displacement. Awareness of screen plugging is not widely spread, and many practicing engineers do not pay enough attention to its implications. In this paper, we discuss the causes, consequences, and ways of determining plugging and recommend best practices to reduce the risk of screen plugging. First, we review the various reasons for screens to get plugged during openhole completion installations and explain in detail undesirable events caused by screen plugging such as: Inability to properly displace wellbore fluids Inability to fully pack the screen annulus Damage to screens during displacement and gravel packing We also review downhole gauge data of several jobs to identify and discuss screen plugging signatures and their outcomes. Additionally, we discuss potential preventive measures. In openhole completions, it is very common to run screens in wellbores containing solids-laden fluids intentionally or unintentionally. Poor wellbore displacement or improper fluid conditioning can result in leaving some bigger size solids in the screen-running fluid (SRF), which could plug the screens. Also, the exposure of reactive shales to water-based fluids can destabilize the shales and lead to plugging. In some cases, the SRF quality control is not properly accounting for the actual flow inside the screen while running in hole, resulting in a false pass. We present several case histories of downhole gauge data analysis, showing evidence of screen plugging leading to excessive treating pressure, incomplete gravel pack, and, in a few cases, screen erosion during gravel pack operations. To prevent screen plugging, it is necessary to properly model all the displacement stages, pay attention to proper conditioning and quality control of the fluid, and ensure compatibility of the fluids with shales. A comprehensive review of screen plugging during sand control installation phase and its potential consequences supported with extensive downhole gauge data has not been published previously. This paper will be a valuable source of knowledge for completion engineers and help them better design and execute future operations.

Coupling analysis of cylinder block for two-stroke aviation piston engine

The aluminum alloy block is a component of aircraft piston engine, and it is prone to fatigue cracks when working in a thermal mechanical coupling state for a long time. Establish a GT-POWER simulation model for a certain type of engine, verify the accuracy of the model, obtain boundary parameters such as temperature and pressure of the engine block under harsh operating conditions through the model, and divide the cylinder wall into gradients based on the engine operating conditions to obtain the surface heat transfer coefficient of the block, and then obtain the temperature field distribution of the engine body. The coupling analysis of the cylinder burst pressure and temperature field of the engine block under harsh working conditions showed that the maximum stress of the engine block was 292.55 MPa and the maximum deformation was 0.39 mm, with thermal load being the main factor causing deformation. Conduct a complete engine bench test, and under the 1000 h bench durability test, there are no cracks on the engine block, indicating that the design and analysis meet the requirements.

Analisa Kualitas Pelayanan dengan Pendekatan Service Quality dan Quality Function Deployment (Studi Kasus: Bagian PSA (Pelayanan Satu Atap di ITATS)

Higher education becomes not only the center of knowledge but also a place to explore and improve all aspects of excellent service that can improve its image. Therefore, every university will be increasingly required to always provide good service because students are always looking for the one that provides the best service for them. Institut Teknologi Adhi Tama Surabaya, or ITATS, is the most complete and qualified engineering college in East Java. However, there are still deficiencies in service quality that need to be improved, such as the quality of service for new student registration. The registration service at ITATS is still quite complicated, inefficient, and ineffective. This study aimed to determine the attributes of service quality and improve service performance in the future. It employed the service quality (servqual) and quality function deployment (QFD) methods. The results of the ITATS service quality research indicated that the biggest gap was in the assurance dimension, with a value of -0.39. Meanwhile, theemployee was the attribute with the highest level of importance that could provideservices effectively and efficiently

Insights into thermodynamic performance of a hypersonic precooled air-breathing engine with a complicated multi-branch closed cycle

An advanced precooled airbreathing engine with a closed Brayton cycle is a promising solution for high-speed propulsion, of which the Synergetic Air Breathing Rocket Engine (SABRE) is a representative configuration. The performance of the latest SABRE-4 cycle was analyzed in this paper. Firstly, a relatively complete engine performance model that considers the characteristics of turbomachinery and heat exchangers was developed. Then, Sobol’ global sensitivity analysis of key performance parameters was carried out to identify the most influential design variables. Optimal specific impulses under different target specific thrusts were obtained by particle swarm optimization, of which the thermodynamic parameters corresponding to a specific thrust of 1.12 kN·s·kg−1 and a specific impulse of 3163 s were chosen as the design values. Four different control laws were analyzed in contrast, and the charge control method had the strongest ability of thrust regulation as well as maintaining a favorable specific impulse performance. Finally, working characteristics under the charge control and over a typical flight envelope were calculated, in which the average value of the maximum specific impulse was as high as 5315 s. This study would help to deepen the understanding of SABRE-4 thermodynamic characteristics and other precooled airbreathing engine cycles with similar layouts.

Predicting Onset of Sand Production in Oil Wells using Machine Learning

Sand production in oil wells is a significant challenge that negatively impacts productivity and compromise equipment integrity. This study explores the application of Optimized Support Vector Machine (SVM) binary classification algorithm to predict the onset of sand production in oil wells. A dataset from 63 oil wells was utilized, and class labels were determined based on the bulk and shear modulus product. The model development incorporated geological and mechanical parameters that could influence sand detachment such as: Young’s modulus, Poisson’s ratio, minimum and maximum horizontal stresses, overburden pressure, pore pressure, depth, fracture gradient, and formation strength. Instances above the threshold of 8E+11 were classified as indicative of no sand production, while those below were considered potential sand production scenarios. The SVM model demonstrated remarkable accuracy in predicting sand production onset, trained and tested rigorously with field data. The model's accuracy was evaluated using statistical parameters, such as: accuracy (ACC), sensitivity (SE), specificity (SP), and Matthew's Correlation Coefficient (MCC). From the results, the model achieved a score of 1 across all parameters, indicating high reliability and accuracy in sand production prediction. The practical implications of this model are significant, offering assistance to completion engineers in making proactive decisions regarding sand control strategies. Furthermore, the integration of this model into oil and gas industry processes can optimize operational efficiency by foreseeing potential sand production events, hence, preventing production impairment and ensuring loss prevention.

An Integrated Monitoring, Diagnostics, and Prognostics System for Aero-Engines under Long-Term Performance Deterioration

In the field of aircraft engine diagnostics, many advanced algorithms have been proposed over the last few years. However, there is still wide room for improvement, especially in the development of more integrated and complete engine health management systems to detect, identify, and forecast complex faults in a short time. Furthermore, it is necessary to ensure that these systems preserve their capabilities over time despite engine deterioration. This paper addresses these necessities by proposing an integrated system that considers the joint operation of feature extraction, anomaly detection, fault identification, and prognostic algorithms for engines with long operation times. To effectively reveal the actual engine condition, light adaptive degraded engine models are computed along with different health indicators that are used as inputs to train and test recognition and prediction models. The system is developed and evaluated using a specialized NASA platform which provides data from a turbofan engine fleet simultaneously experiencing long-term performance deterioration and faults. Contrary to other compared solutions, our results show that the proposed system is robust against the effects of engine deterioration, maintaining its level of detection, recognition, and prediction accuracy over a total engine service life. The low computational cost algorithms has generally fast performance in all stages, making the system suitable for online applications.

Application and Progress of Artificial Intelligence in Oilfield Drilling

Intelligent drilling and completion technology was an organic integration of drilling and completion engineering with advanced technologies such as artificial intelligence, big data, and cloud computing. It could achieve precise characterization, optimized decision-making, and closed-loop control of the oil and gas drilling and completion process. It was expected to significantly improve drilling and completion efficiency, reservoir drilling rate, and oil and gas recovery rate. It was a research frontier and hotspot in the field of oil and gas. This article constructed an artificial intelligence application scenario system for oil and gas drilling and completion based on engineering practice. It also elaborated on the current research status of intelligent drilling and completion theory and technology at home and abroad. Apart from that, the article summarized the challenges and key research directions faced by intelligent drilling and completion technology research. The aim was to provide a reference for accelerating basic theoretical research, technology promotion, and application of intelligent drilling and completion technology in China.

Upgradation of aircrew with minor musculoskeletal injuries in the operational bases: Need for a relook

Objectives: Musculoskeletal injuries (MSKI) have been one of the most common contributors to disabilities among aircrew. The existing policy mandates all cases of MSKI in aircrew of the Indian Air Force, including minor injuries such as a sprain of small joints and phalangeal fractures to be evaluated at the Institute of Aerospace Medicine (IAM), majority of which do not warrant a complete Human Engineering (HE) assessment. Hence, a need was felt to decentralize evaluation and empower other boarding centers/operational bases with local aerospace medicine specialists to carry out the evaluation. Material and Method: A retrospective analysis was carried out of a total of 930 cases of MSKI among serving aircrew who reported to IAM between Jan 2016 and Oct 2020. Results: About 27.68% of cases were of lower limb injuries and 16.52% of cases were of upper limb injuries. About 36.77% of cases of upper limb and 52.71% of cases of lower limb injuries were treated surgically while 63.23% upper limb and 47.29% lower limb injuries were managed conservatively. Full functional recovery within 12 weeks was seen in a significant number of conservatively treated distal upper and lower limb injuries not involving joints. Conclusion: HE assessment of MSKI at IAM is comprehensive including exposure to simulated aeromedical stressors. However, certain minor musculoskeletal disabilities did not require full HE evaluation and simulator facilities of IAM. Sending aircrew with such minor disabilities from field units to IAM amounts to an administrative obligation that can be avoided by empowering other medical boarding centers and local operational bases which have aerospace medicine specialists. This paper discusses the procedure of conduct and facilitation of aeromedical evaluation of aircrew in the non-flying medical category with certain minor MSKI in the field.

Design and research of a heavy load fatigue test system based on hydraulic control for full-size marine low-speed diesel engine bearings

As the power density design indicators of marine low-speed diesel engines gradually increased, resulting the loads of marine low-speed diesel engine bearings become increasingly complex. It's easy to cause crankshaft fatigue damage, leading to a very significant economic loss. Due to the maximum thrust loads of full-size-bearing is larger than 2000kN, the bearings performance tests are very expensive on a complete diesel engine. So, newly developed bearings must be verified on a specialized test rig. The research goal is to design a novel fatigue life test system (Bearing diameter: 300mm–520mm, Speed: 5r/min-200r/min, Thrust: 0kN–2800kN) that can simulate the working conditions of full-size low-speed marine diesel engine bearings. Adopting the advanced hydraulic-based control passive pressurization technology. Multi-platform joint simulation technology is used to make sure that the maximum thrust of the test rig is proportional to the eccentricity of the eccentric shaft. The final eccentricity of the shaft is determined by 3mm for test rig. The results based on 475mm×150mm bearing is published for the first time. The test load can be well enveloped in the load of the target diesel engine, with maximum load fluctuation less than 0.2%. The test rig can meet the performance testing requirements of full-size bearings.

A method to quantify the advantages of a variable valve train for CI engines

Today’s CI engines are subject to strict regulations of pollutant emissions and ambitious fuel consumption targets. Therefore, the interaction between the engine and the exhaust aftertreatment system (ATS) has become increasingly important. Numerous studies have shown that a variable valve train (VVT) improves the interaction between engine and ATS. However, most of these studies either quantify the advantage on a specific engine or only present complex CFD models, such that the results are not easily transferable to different engines. Thus, engine manufacturers cannot directly use these results to assess the advantage of various VVT strategies for their engines. In this paper, we propose a cycle-discrete cylinder model based on first principles which allows to simulate various VVT strategies. In contrast to present methods based on CFD, the proposed cylinder model can be realized with the equations presented. Furthermore, the model is identified with measurement data of an engine without a VVT. A separate engine, which is retrofitted with a fully VVT, is used to validate the proposed modeling approach. Using the identified model in combination with a mean-value model of the air path, we are able to simulate the effects of early intake valve closing, early exhaust valve opening, and cylinder deactivation for a complete CI engine that has no VVT installed. The model is then used to highlight the advantage of a VVT for two scenarios at part-load operation. At cold start, where the temperature of the ATS must be increased quickly, variable valve timing achieves higher enthalpy flows to the ATS while also lowering engine-out NOx emissions when compared to a standard engine strategy. If the ATS is at the operating temperature, cylinder deactivation achieves significantly higher enthalpy flows which prevents the ATS from cooling down. In addition, cylinder deactivation also lowers fuel consumption and engine-out NOx emissions.

Investigation of consolidation/thermal insulation property and mechanism of casing cement in the heat-insulating section of geothermal production well

ABSTRACT In the process of geothermal exploitation, heat loss often occurs in the heat-insulating section of the production well, resulting in a decrease in heat extraction efficiency. However, there have been few studies on thermal insulation cement for geothermal well, lacking complete engineering application properties evaluation. In view of this, a new type of thermal insulation composite cement was successfully developed by incorporating thermal insulation filler (Hollow glass beads, HGB), heat stabilizing material (SiO2) and additives. The engineering application properties were evaluated using standardized methods, and the results demonstrated excellent rheology and stability of the cement slurry. The 14d compressive strength of the cement stone reached 21.24 MPa, and the thermal conductivity remained stable at 0.1535 W/(m·K). Finally, the consolidation/thermal insulation mechanism of the material was investigated. Analysis showed that the secondary hydration of SiO2 could generate more C-S-H, and additives could regulate the hydration reaction of slurry. The excellent thermal insulation property of material was derived from interface lattice scattering, the low thermal conductivity of HGB, and the gas heat-conduction recession within HGB. The study results provide a new idea to solve the problem of heat loss of geothermal production well from the perspective of material development.