Engine Damages Research Articles

Remaining useful life prediction based on a PCA and similarity methods

Aircraft engine failures or damages not only incur substantial financial losses but also present risks of injuries or even fatalities. Hence, it is of utmost importance to devise an effective method to predict potential failures in advance, thereby mitigating accidents and minimizing losses. This paper proposes a novel approach that combines a principal component analysis (PCA) with similarity methods to establish a degradation trajectory database and predict the remaining useful life (RUL) of new engines by identifying similar trajectories. Firstly, the data dimensionality is reduced using a PCA to create a health indicator. The validity of the reduced data is confirmed by calculating the Spearman correlation coefficient between the health indicator and the system RUL. During the similarity comparison process, the Manhattan distance is employed for the similarity calculation, and parameter optimization is performed on the length of selected time segments and the number of chosen similar trajectories to optimize the similarity of RUL prediction model, resulting in the optimal prediction results among all engine test sets. Notably, this paper introduces the feasibility of employing the Manhattan distance in similarity method-based prediction, which is superior to the commonly used Euclidean distance calculation method found in most literature. This finding offers innovative ideas and perspectives for advancing RUL prediction methodologies. By adopting the proposed approach, the occurrence of accidents and losses associated with aircraft engine failures can be substantially reduced, leading to enhanced safety and economic benefits.

Coupling effect of shaft torsional vibration and advanced injection angle on medium-speed diesel engine block vibration

Engine body vibration is an important safety concern for diesel engines as it can lead to severe engine damages and even catastrophic failures. Traditional methods for excitation computation assume that the rotational speed and the cylinder pressure remain stable under each working cycle, which makes it impossible to precisely predict vibration peaks at certain frequencies. But in practice, the existence of shafting torsional vibration will lead to the fluctuation of rotational speed and cylinder pressure. To predict engine block vibration more accurately, this paper proposes a novel method considering the instantaneous variations in rotational speed and cylinder pressure. It is implemented by two steps. Firstly, an innovative model considering the coupling effect between shaft torsional vibration and advanced injection angle is proposed, it particularly explains how the cylinder pressure and instantaneous rotational speed vary due to the coupling effects. Secondly, the excitation forces that cause block vibration are analyzed and their computational formulas are improved. This method also considers the offset of excitation loading position caused by torsional vibration. The coupling model is experimentally verified and the excitations are loaded into a finite element model of the diesel engine for vibration response prediction. The results reveal that the coupled model can predict vibration peaks at sideband frequencies and thus makes the frequency spectrum much richer than that of the traditional method. Furthermore, it shows that the acceleration results obtained by the coupled model have better prediction accuracy than those obtained from traditional methods, with the deviation percentage reducing from 6.31% and 8.41% to 0.64% and 0.32% in the X and Z direction. It indicates that the coupled model is more reliable in predicting the vibration response of the engine block. Finally, the effect of advanced injection angle on engine block vibration is investigated and the optimal value of the advanced injection angle is determined to be 29 CA, which makes the engine block vibration reduced by 3.60%, 2.72%, and 3.16% in the X, Y, and Z direction comparing to the original advanced injection angle. Overall, this study presents an improved approach for predicting engine block vibrations and offers valuable insights for the design of shafting structures and fuel injection parameters in marine diesel engines.

Numerical Steady and Transient Evaluation of a Confined Swirl Stabilized Burner

Lean premixed combustion technology became state of the art in recent heavy-duty gas turbines and aeroengines. In combustion chambers operating under fuel-lean conditions, unsteady heat release can augment pressure amplitudes, resulting in component engine damages. In order to achieve deeper knowledge concerning combustion instabilities, it is necessary to analyze in detail combustion processes. The current study supports this by conducting a numerical investigation of combustion in a premixed swirl-stabilized methane burner with operating conditions taken from experimental data that were recently published. It is a follow-up of a previous paper from Farisco et al., 2019 where a different combustion configuration was studied. The commercial code ANSYS Fluent has been used with the aim to perform steady and transient calculations via Large Eddy Simulation (LES) of the current confined methane combustor. A validation of the numerical data has been performed against the available experiments. In this study, the numerical temperature profiles have been compared with the measurements. The heat release parameter has been experimentally and numerically estimated in order to point out the position of the main reaction zone. Several turbulence and combustion models have been investigated with the aim to come into accord with the experiments. The outcome showed that the combustion model Flamelet Generated Manifold (FGM) with the k-ω turbulence model was able to correctly simulate flame lift-off.

Characterization of gas turbine ingested sand particles based on electrostatic signal

Particle ingestion into a gas turbine can have serious effects on both performance and engine in-service reliability. Thus there exists a need for in situ monitoring and characterizing particulate matter entering an aircraft engine inlet for the purposes of engine damages estimation and prognosis. This paper presents the initial development of Ingested Debris Monitoring System (IDMS) signal processing method of characterizing the ingested particles. A theoretical analysis and simulation study were carried out to study the relationships between the characteristics of the ingested sand particles and the features of the IDMS signal both in frequency- and time-domain. A Finite-Element Modeling (FEM) for the IDMS Sensor was developed, then the validated FEM modeling was used for simulation experiments of particles ingestion under various conditions of different particle moving speeds, concentrations and charge-to-mass ratios. Results of the theoretical analysis and simulation study demonstrates the feasibility and effectiveness of the proposed method to provide real time information characterizing the size and concentration of ingested sand particles, and will serve as an impetus to carry out further research.

The effectiveness of coconut coir as tar adsorbent in liquid smoke integrated into the pyrolysis reactor

Tar is a toxic polycyclic aromatic hydrocarbon (PAH) compound that can cause pipe clogging problems and engine damages. Thus, the purpose of this study is to assess the effectiveness of coconut coir from coconut shells (Cocos nucifera) as tar adsorbent integrated into the pyrolysis reactor. The pyrolysis process occurred at 400 °C for 4 h in equipment consisted of a combustion reactor, filter reactor as an adsorbent, and condenser. The results of FTIR and SEM analysis have shown that coconut coir could be effectively used as a tar adsorbent. The GCMS test showed no PAH compounds in liquid smoke. Also, the physicochemical properties of liquid smoke from coir adsorbent were better than liquid smoke without adsorbent. The tar trapped in the coir had an increase in calorific value compared with raw coir. Moreover, the presence of tar in coir had significantly improved the thermal degradation properties of coconut coir.

Engine knock detection for a multifuel engine using engine block vibration with statistical approach

Engine knock is an obstacle for maximizing CNG fuel utilization on a Diesel-CNG Dual Fuel engine. Prolong experience of this phenomenon may lead to severe engine damage. The low intensity of this phenomenon is difficult to recognize due to other noises from the engine. Thus, improper engine tuning techniques may make this phenomenon unnoticeable until the engine damages. Knock phenomena on such engines may not be detected in the combustion analysis graph. Its random occurrence in consecutive engine cycles makes it difficult to be seen using visual data. This knowledge gap, if closed, can lead to an opportunity for knock avoidance on the multifuel engine. This work proposed a method to quantify the knock occurrence based on engine block vibration using a single piezoelectric knock sensor. The knock occurrence was detected by comparing the calculated knock index with the knock threshold, determined using a statistical three-sigma rule analysis. This method can index the knock intensity, detect the engine knock occurrence, and visualize the knock phenomenon.•This paper describes an alternative engine knock detection technique based on engine block vibration.•This method proposes the knock threshold determination based on statistical three-sigma rule analysis.•This method is capable of visualizing the knock phenomenon in consecutive and at each engine cycle.

Analysis of in-cylinder pressure oscillation and its effect on wall heat transfer

In-cylinder pressure oscillations in internal combustion engines have been associated with increased heat losses and damages to the engine components. The links between the acoustic waves and the increased heat transfer (and potentially ensuing engine damages) have not yet been well understood. In this study, a high-fidelity large eddy simulation model incorporating an auto-ignition model is used to simulate the combustion process and the associated pressure oscillation at various engine operating conditions. The study serves to develop a better understanding of the acoustic waves in a combustion chamber and their effect on wall heat transfer. First, a simplified model of the pressure oscillations is proposed and shown to accurately characterize the pressure in the combustion chamber. Second, the simplified pressure model and acoustic theory are leveraged to develop a model of the in-cylinder gas velocities. Finally, a heat transfer model is presented that takes into consideration the pressure/velocity oscillations and the inherent acoustic properties of the trapped gas. The increase in heat transfer is shown to primarily stem from an increased heat transfer coefficient due to the velocity oscillations of the trapped gas. The results are consistent with previously observed experimental measurements of the heat flux in the presence of pressure oscillations.

Proposing new hybrid nano-engine oil for lubrication of internal combustion engines: Preventing cold start engine damages and saving energy

In this paper, viscosity of SAE 5W50 oil enriched by MWCNT and ZnO nanoparticles with combination ratio of 1:4 is experimentally investigated in solid volume fractions of 0.05, 0.1, 0.25, 0.5, 0.75, and 1% and temperature range of 5 to 55 ˚C. It is done with the aim of feasibility study on achieving a modified nano-engine oil that can minimize cold start engine damages using nanoparticles. According to results, produced nano oil with concentrations less than 0.25% selected as modified engine oil. Almost 9% reduction in viscosity of nano-oil with solid volume fraction of 0.05% compared to ordinary engine oil in 5 °C and shear rate of 666.5 (1/sec) was one of the very interesting results of this investigation which makes pumping easier and oil will enter the lubrication cycle faster and this minimizes cold start damages. Moreover, Presence of nanoparticles improves heat transfer from engine parts. The result showed that in temperature range of 35–55 °C, and solid volume fractions less than 0.25%, our proposed nano-oil is more appropriate for high temperature usage too, because of lower dependency of its viscosity to temperature in comparison to pure 5W50 engine oil. A mathematical correlation was proposed to predict viscosity of nano-engine oils used in this research. R-Squared = 0.9685 of this correlation shows its high accuracy.

Sound Reconstruction of an Overdetermined Mixture in a Mini Plant: An Experimental Study

In this study, we propose a sound-based signal analysis technique emitted by rotating machines. Three water pump machines are set in a row to reflect a mini plant. We raise an overdetermined case with four sensors that are used to record three machines’ signal sounds with unbalanced, normal and bearing fault conditions. We use non-negative matrix factorization (NMF) approach to reconstruct the signal sounds of each machine which had previously been mixed. Based on the results, the type of engine damages can be determined based on the fundamental frequency of each machine. The first reconstructed signal Ŝ1 is similar to the baseline signal of normal machine with LSD of 1 and MSE of 5.84 × 10−9 The second reconstructed signal Ŝ2 has a similarity to the baseline signal of the machine with bearing fault with LSD of 1 and MSE of 1.10 × 10−7, while the third reconstruction signal Ŝ3 is similar to the machine’s baseline signal with unbalanced condition,that is, LSD of 1.02 and MSE of 1.38 × 10−8.

Improving engine oil lubrication in light-duty vehicles by using of dispersing MWCNT and ZnO nanoparticles in 5W50 as viscosity index improvers (VII)

The objective of this study is to offer a suitable nano-lubricant (engine oils containing nanoparticles) to use in light-duty automotive industries in order to reach a higher ability and efficient oil in comparison to ordinary engine oils, in order to reduce cold start engine damages. Therefore, in present study a feasibility study of using a new nano-engine oil containing a combination of MWCNT (multi wall carbon nanotubes)-ZnO nanoparticles with the ratio of 30–70% has been arranged. Results of experimental study show a considerable decrease in viscosity of nano-engine oil (in comparison to viscosity of pure 5W50 oil) after adding 0.05% and 0.1% nanoparticles to 5W50. This viscosity reduction, reduces the damage caused by starting up the engine in cold start condition. In order to predict the viscosity of this applied nano-engine oil (obtained from experimental studies), the efficiency of using a mathematical correlation using response surface methods (RSM) was investigated for viscosity prediction. For the proposed correlation, R2 is equal to 0.9715 that shows its acceptable accuracy. An artificial neural network has also been used as the second method to predict viscosity in the range of 5 °C–55 °C and in solid volume fractions of 0.05%–1%. Selected structure of Artificial Neural Network with R = 9.999e−01 is the most optimal and precise structure among 100 studied structures.

Towards a green bulk-scale biobutanol from bioethanol upgrading

Biobutanol is attracting increasingly interest as a source of renewable energy and biofuels because of its many advantages over bioethanol that include higher energy density, fuel efficiency, and reduced engine damages. Currently, there is a growing interest in producing biobutanol from bioethanol, in view of the tremendous potential benefits of this transformation for the bulk production of biobutanol in a target specific manner. This perspective paper describes recent progress for the ethanol to butanol process. The different catalysts, including homogeneous and heterogeneous catalytic systems, for ethanol to butanol are outlined and compared, and the key issues and requirements for future developments are highlighted. A major challenge for further development and application of ethanol to butanol process is to find an optimal balance between different catalytic functions and to suppress the formation of side products that has plagued most catalytic bioethanol upgrading systems.

Analysis of a Railcar Engine Damages Using Forensic Investigation

This paper describes the researches made by the authors in order to find the causes were a railcar engine damages. Investigations were made in Brasov and also in Czech Republic, onto engine manufacturer. Important conclusions and results were uses for establish what actions are necessary for such a failure will not reoccur in the future.

The Choice of Vibroacoustic Signal Measures in Mechanical Fault Diagnosis of Diesel Engines

The use of diesel engines as a basic power unit of electric generators in big ship crafts and as a power unit in smaller ship crafts is very common. Low fuel consumption, high resistance to overload and long life span are the basic features which made these engines so commonly used. The development of electronic control of high pressure injection systems of the engine made the service of such an engine not so simple any more. What is more, control systems are directed at reducing fumes toxicity, which does not have to go hand in hand with early detection of engine damages. It happens in the case of a particular group of mechanical damages of the engine, which are undetectable by an onboard diagnostic system in the early stage of the development. The injection system is able to choose regulation parameters in such a way so that the composition of the air fuel mixture is in optimal range, and as a result it hides the information about the damage.This paper presents the results of analysis of the usefulness of the chosen vibroacoustic signal measures in the process of detecting damages of this type.

실시간 가스터빈 엔진 시뮬레이터를 적용한 소형 제트엔진 성능시험장치 개발

가상엔진 시뮬레이터를 이용한 시험장치는 실제 엔진을 이용한 시험과 유사한 시험 수행을 통하여 엔진 시험 횟수를 줄이고 동일한 조건에서 반복 시험이 가능하므로 엔진 정비 및 운용비용을 감소시켜 준다. 그리고 실제 시험에서 수행하기 어려운 극한 상황을 쉽게 구현할 수 있기 때문에 실제 엔진 시험 시 발생할 수 있는 엔진 손상 및 위험한 시험을 대체해 준다. 본 연구에서는 사전 연구를 통해 개발하였던 소형제트엔진 성능시험장치에 실시간 엔진 모델을 적용하여 실제 엔진 시험과 가상 엔진 시험을 다목적으로 수행할 수 있는 업그레이드 된 소형제트엔진 성능시험장치를 개발하였다. 새로 개발된 다목적 소형 제트엔진 성능시험장치는 교육용 및 연구용으로 더욱 다양하게 활용될 수 있을 것으로 기대된다. Test device using virtual engine simulator can help reduce the number of engine tests through tests similar to the actual engine tests and repeat the test under the same condition, and thus reduce the engine maintenance and operating costs. Also, as it is possible to easily implement extreme conditions in which it is hard to conduct actual tests, it can prevent engine damages that may happen during the actual engine test under such conditions. In this study, an upgraded small jet engine performance test device was developed that can conduct both real and virtual engine test by applying real-time engine model to the existing micro jet engine performance test device that was previously developed by authors. This newly developed multi-purpose small jet engine performance test device is expected to be used for various educational and research purposes.

LES prediction and analysis of knocking combustion in a spark ignition engine

Highly boosted spark ignition (SI) engines are more and more attractive for car manufacturers in terms of efficiency and CO2 emissions. However, thermodynamic conditions encountered in these engines promote the occurrence of abnormal combustions like knock or super-knock, which are experimentally difficult to analyse due to the risks of engine damages. The Reynolds averaged Navier–Stokes (RANS) method mainly used in industry for piston engines is not the most appropriate as knock does not always affect the mean cycle captured by RANS. Using an accurate LES compressible code and improved versions of ECFM-LES (Extended Coherent Flame Model) and TKI (Tabulated Kinetics of Ignition) models allowing a full uncoupling of flame propagation and auto-ignition reaction rates, this work demonstrates for the first time that LES is able to describe quantitatively knocking combustion in a realistic SI engine configuration. Contrary to previous studies (Fontanesi et al., 2013 [5]) (Lecocq et al., 2011 [4]), a quantified knock analysis is conducted based on a specific post-processing of both numerical and experimental data. LES is able to predict the in-cylinder pressure variability, the knock occurrence frequency and the mean knock onset crank angle for several spark timings. A 3D analysis also demonstrates that knock occurs at random locations, mainly at the exhaust valves side. Knock intensity is found proportional to the fresh gases mass burned by auto-ignition at low knock intensities, while an exponential increase at the highest intensities suggests the influence of additional factors like the knock location in the cylinder or complex behaviour of knocking combustion.

Overview of the main mechanisms triggering low-speed pre-ignition in spark-ignition engines

Low-speed pre-ignition has become of great concern since it represents a strong limit to any further downsizing of gasoline engines. The increase of pressure and temperature inside the combustion chamber at high loads can indeed lead to a premature auto-ignition of the mixture and to severe engine damages. Several hypotheses have been formulated but there is no consensus to explain and demonstrate the cause of low-speed pre-ignition. This article provides an overview of the mechanisms that might lead to low-speed pre-ignition. A general discussion and a synthesis of the favourable conditions for auto-ignition are first introduced. Fundamentals of auto-ignition in homogeneous gaseous phase are discussed and confronted to concrete experimental observations of low-speed pre-ignition. The real operating conditions of modern gasoline engines complicate the analysis of auto-ignition because spatial and cycle-to-cycle fluctuations are linked to various physicochemical phenomena involved in the mixture preparation process. At the same time, the increase in temperature and pressure with load enhances the mixture reactivity and any perturbation at the end of the compression can unbalance the mixture and lead to uncontrolled low-speed pre-ignition. A classification of these mechanisms into three groups is proposed to categorize pre-ignitions resulting from auto-ignitions in the gaseous phase, or from auto-ignitions resulting from interactions between either a liquid or a solid phase and the gaseous mixture. Finally, the impact of mixture dilution with burned gases, mixture temperature, liquid films and deposits is examined for different engine settings, fuels and charge motions to illustrate each of these three groups.

Analysis of pre-ignition in highly charged SI engines: Emphasis on the auto-ignition mode

Downsized spark ignition engines are characterized by high efficiencies but favor abnormal combustions like pre-ignition and knocking. The first appears under the form of a local ignition prior to spark ignition, leading to an early flame propagation. That may be followed by a violent auto-ignition causing drastic engine damages. Such heavy knocking limits the maximum load of SI engines and thus the scale of downsizing. Pre-ignition appears randomly during engine operation. Its origins are still not fully understood, but it is observed that once pre-ignition is triggered it may lead under very similar conditions either to soft engine knock or to destructive pressure oscillations. Thus, there is a strong interest in the comprehension of the impact of pre-ignition on the pressure evolution during an engine cycle. Literature shows that the flame propagation mode determines knock severity. The propagation mode depends on the coupling between the pressure wave and the reactive front. This interaction is determined by the thermodynamic conditions in the chamber and may be predicted numerically by computations of chemical kinetics and acoustics.In this work, a specific methodology was defined combining detailed chemical kinetic computations with a two-zone combustion analysis in order to determine the flame propagation mode for a wide range of operating conditions. Experimental data recorded on different engines were analyzed and showed that pre-ignition does not stringently trigger violent auto-ignition. These results demonstrate also that one pre-ignition may induce several auto-ignitions, leading either to deflagration or to a transition into detonation. This transition depends not only on the quantity of end-gas reacting, but mainly on the thermodynamic conditions, favorable or not, for coupling the acoustic pressure wave with the reactive front. The proposed methodology may help to identify fuel characteristics and operating conditions lowering the probability of engine damage caused by such phenomena.