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This research examines the performance variables, combustion, and the amounts of NOx, CO, HC, and K emissions in a diesel engine, using blends of hemp biodiesel and oleic acid biodiesel with conventional diesel. To obtain biodiesel from hemp oil and oleic acid, a heterogeneous sulfonated camphor catalyst (CASU-AL) was used for the transesterification of hemp oil and the esterification of oleic acid respectively. Several characterization tests were performed on the CASU-AL catalyst such as the acid-base titration method for the quantification of acid sites, XRD analysis to determine the areas of the carbonaceous material, images and composition of CASU-AL were obtained with SEM and EDX, the porosity characteristics and surface properties were assessed with BET analysis. Constant operating conditions were used in the autogenous reactor with a temperature of 200 °C, a reaction time of 23 min, and a quantity of sulfonated camphor catalyst of 0.033 % w. Several analyses were applied to the CASU-AL, several mixtures were made with conventional diesel, and different biodiesels were obtained in the laboratory. The mixtures were conventional diesel (DIE-100), hemp oil biodiesel (BAC-100), oleic acid biodiesel (BAO-100), Diesel-BAC mixture with 30 % hemp oil biodiesel (MDBAC-30), and Diesel-BAO mixture with 30 % oleic acid biodiesel (MDBAO-30). For the tests in a diesel engine, three speed zones were selected in the engine to identify the behavior at low speed at 1,200 rpm, medium speed at 1,400 rpm, and high speed at 1800 rpm. Combustion tests reveal that no significant variation is observed in the characteristics and performance of the diesel engine, however, in the gaseous products derived from combustion, significant reductions in carbon monoxide, unburned hydrocarbon, and an increase in nitrogen oxide emissions were achieved when using DIE-100 compared to BAC-100 and BAO-100. The tests showed a reduction in NOx, CO, HC, K, and smoke emissions when testing MDBAC-30 and MDBAO-30 in a laboratory diesel engine. A comparison of the properties of hemp oil-oleic acid biodiesels BAC-100 and BAO-100 with conventional diesel DIE-100 revealed that the different biodiesels used could be used alone or in a blend of 70 % diesel and 30 % biodiesel to fuel diesel engines by decreasing air pollutants and promoting lubricity in the engine. Our findings revealed that MDBAC-30 and MDBAO-30 showed the best engine performance and lowest emissions among all the tested fuels. In other words, MDBAC-30 and MDBAO-30 are the ideal fuel blends for diesel engines and do not require any modification to the engine. [ABSTRACT FROM AUTHOR]

Two engine oil additives with graphene were tested in diesel engines. The first was a graphene oxide (GO)-based, commercially available additive that the supplier recommends using at a 3% v/v concentration in engine oil. The second was a graphene nanoplatelet (GNP)-based additive that is under development, which is more concentrated and allows for the addition of a much smaller amount of additive. Using the GO additive results in a reduction of brake-specific fuel consumption from 0.2% to 0.7%, depending on the engine load, and a 2% reduction in fuel consumption when the engine is run without load. The use of 0.1% wt of GNPs led to 0.4% of fuel savings on an ESC emission cycle. Increasing the GNP concentration to 0.2% did not further reduce fuel consumption. [ABSTRACT FROM AUTHOR]

This paper presents the design and development project of an engine test stand specifically constructed for ground testing of miniature turbine jet engines (MTJEs) along with conclusive results of the conducted investigations. The tested engines serve as the propulsion system for an unmanned aerial vehicle (UAV) platform. The engine test stand was used to determine various operating parameters of the engine, with a particular focus on recording variations and changes in temperature and pressure at the engine control cross-sections: behind the compressor, the combustion chamber, and at the final cross-section of the nozzle. The analysis of the direct test results allowed the evaluation of the engine's behavior under hydration conditions and documents the quantitative and qualitative response of the control system of the engine. Of particular interest are the results showing an increase in exhaust system temperature with a decrease in the temperature in combustion chamber under hydrated conditions. The test program assumed and considered the acting loads and forces in both standard and specific flight conditions, including scenarios for a heavy rain. The preliminary evaluation of the investigation results provided data and insights required for further analysis. Quantitatively, the measured temperature value in the exhaust system does not exceed 700 °C and the temperature increase resulting from the introduction of water and the engine's response to the out-of-operation event is approximately 50 °C for the JetCat 140. Qualitatively different effects were observed in the combustion moment, consisting in a drop in temperature values during the introduction of water into the engine flow channel. The introduction of water into the GTM 140 inlet revealed no significant changes in the variations of pressure and temperature measured in selected engine design sections. Based on the knowledge and experience gained, a fully operational test stand to monitor the parameters and performance of the MTJEs, which are used for aerial target propulsion, was developed. [ABSTRACT FROM AUTHOR]

Copyright of MTZ: Motortechnische Zeitschrift is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Automobile Technology & Material is the property of Automobile Technology & Material Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Generative AI has recently gained the ability to generate computer code. This development is bound to affect how computer programming is taught in higher education. We used past programming assignments and solutions for textbook exercises in our introductory programming class to analyze how accurately one of the leading models, ChatGPT, generates solutions. We selected the ChatGPT-4 available through the Bing search engine for our testing. We used a one-tailed test to calculate success percentage of the textbook versus ChatGPT solutions to determine if there was a statistically significant difference. Neither the book nor ChatGPT provided perfect solutions. Analysis of the results showed that the generated code does not always meet the programming requirements, but also that instructions for generative AI coding and for traditional programming can be improved. We conclude with recommendations for incorporating generative AI in programming classes. [ABSTRACT FROM AUTHOR]

The problem of studying the operating cycle of a pulsating air-breathing engine is important in the context of the occurrence of vibration combustion, as well as the transition of combustion to detonation. The characteristics of a detonation-combustion propjet engine should be significantly higher than the characteristics of air-breathing engines. The article presents the results of a search for ways to increase the specific performance of a valveless ejector pulsating air-breathing engine. The results of fire tests of engines with partial conversion of the original fuel and generation during the operating cycle of peroxides and active centers obtained during cold-flame reactions are presented. As a result of the experiments, a displacement of the combustion zones in the engine downstream into the region of the recirculation zone was obtained. The numerical modeling performed showed an agreement with experiment acceptable for engineering calculations. An increase in engine jet thrust was obtained due to partial fuel conversion and a shift in the ignition zone. The transition of combustion to deformation leads to a significant reduction in engine life. The results obtained and a new method of influencing the work process based on a shift in the combustion zone are discussed. It is shown that an increase in the combustion rate of the air-fuel mixture leads to a change in the acoustic feedback mechanism. During the work, research was carried out to find a reactor design combined with a combustion chamber to produce a small proportion of C 2 H 2 and H 2. To obtain these products, a production method based on the oxidative pyrolysis of methane was chosen. A technical solution was found; it consisted of installing a finned channel cooled by air on the rear wall of the combustion chamber of the reactor. Cooled plates were placed in the front of the combustion chamber and in the second mixer. In these devices, partial cooling of the emitted products of incomplete combustion occurred and the process of methane decomposition was stopped, which made it possible to increase the concentration of C 2 H 2 and H 2 during the combustion chamber purge stroke and thereby increase jet thrust by 25–30%. [ABSTRACT FROM AUTHOR]

The influences of carbon quantum dot nanoparticles in diesel-biodiesel mixture (D80MCB20) were researched on performance, combustion and exhaust emissions. Test engine was run at 2200 rpm including 4.12, 9.61, 15.10 and 20.60 Nm engine loads. ID period was shortened using nanoparticle apart from D80MCB20 CQD 180 ppm. Nanoparticle caused to decrease SFC. CO and HC declined by about 0.76%, 18.02%, 20.30% and 19.48%, 28.57% and 31.16% in case of D80MCB20 CQD 60 ppm, D80MCB20 CQD 120 ppm and D80MCB20 CQD 180 ppm usage according to D80MCB20 at 20.60 Nm respectively. Nonetheless, 48.29%, 55.44% and 56.26% increases were specified on NO x using D80MCB20 CQD 60 ppm, D80MCB20 CQD 120 ppm and D80MCB20 CQD 180 ppm compared to D80MCB20 at 20.60 Nm. It was seen that the carbon quantum dot nanoparticle additive into the diesel-microwave corn biodiesel mixture was a potential candidate to boost performance and reduce CO, HC and soot emissions. • Nanoparticle caused to decrease SFC. • ID period was shortened using nanoparticle apart from D80MCB20 CQD 180 ppm. • NOx increased using nanoparticle addition. [ABSTRACT FROM AUTHOR]

The choice of parameters for the life tests of gas turbine engines is a complex multi-criteria task. In this article, as a tool for solving this task, it is proposed to use simulation modeling of the engine life cycle to select gas turbine engine life test parameters. A three-level system for collecting and processing operational data is considered. It is suggested to combine big data and simulation technologies for engine diagnostics, forecasting, and refining the operation model based on aggregated data on aircraft schedules, flight geography, and weather conditions. Special attention is paid to the choice of a method for modeling the operation of aircraft engines. The authors have developed a number of possible methods for a modeling operation within the framework of the engine life cycle model. The results of a comparative assessment of the proposed methods are presented using the example of choosing the parameters of resource tests of an auxiliary power plant. The analysis of the operation is carried out. [ABSTRACT FROM AUTHOR]

Kerosene/hydrogen-peroxide (H2O2) green propellant system has relatively high operational ratio of oxidizer (O) to fuel (F) that complicates the injector design and its layout. In this research, a procedure of two-stage, like-doublet (O-F-F-O) impinging-jet injector design is presented, where mixing of H2O2 and kerosene occurs between O-O and F-F sprays. Investigations at O/F ratios between 3.75 and 6.25 are performed. The impinging distance, angle, and jet velocity of the two-stage impinging-jet module are the design parameters examined. The PLIF technique is used to observe the spatial droplet distribution of the individual spray. The predicted mixing behavior by overlapping the individual fuel and oxidizer sprays is compared to the actual mixing of the O-F-F-O spray to justify the spray/spray interactions. Detailed behaviors of the fuel and oxidizer sprays are revealed. The effects of O/F ratio and other design parameters on the injector flow dynamics and propellant mixing are examined systematically. With experimentally defined shape factors, an optimum design of the injector element can be determined for a given injector plate. The design of the injector plate for a 450 N thrust engine is demonstrated, and the design is justified by the hot-fire test of the engine. [ABSTRACT FROM AUTHOR]

This study explores the thermal performance of engine fins with different geometries through both experimental investigation and computational fluid dynamics (CFD) analysis. Engine fins are essential for managing thermal stresses and temperature variations in automobile engines. By modifying the shapes of these fins, their heat dissipation efficiency can be improved. The experimental research involves testing engine fins made from various materials, including Aluminum Alloy, Grey Cast Iron, and Magnesium Alloy. For instance, Aluminum Alloy fins demonstrated a temperature range of 1436.2℃ to 1500℃ and a total heat flux range of 509.23 W/m² to 7.0404e5 W/m², depending on the fin geometry. Simultaneously, CFD simulations were performed to thoroughly analyze the fluid dynamics and heat transfer characteristics of different fin geometries. The integration of experimental results and CFD simulations provides valuable insights into the thermal efficiency of engine fins, contributing to the expansion of more effective cooling systems for automotive applications. [ABSTRACT FROM AUTHOR]

The current study is to test and analyze the performance of a compression ignition engine powered by a blend of hemp biodiesel and multi-walled carbon nanotube (MWCNT) nano additive, with a special emphasis on engine parameters. By incorporating the MWCNT nano additive into the hemp biodiesel blends, prospective improvements in engine efficiency, emission reduction, and overall engine performance is noted. The study of these engine characteristics provides vital information into the viability and application of using hemp biodiesel blends in diesel engines but also sheds light on the effectiveness and influence of the MWCNT nano additive on the engine's performance. Through a comprehensive experimental approach, including engine testing and data analysis, the effects of the hemp biodiesel-MWCNT nano additive blends on the engine's operation and functionality are studied. The findings from this study show that the incorporation of MWCNT in hemp biodiesel gives a significant enhancement in brake thermal efficiency and hydrocarbon, carbon monoxide, and smoke emission reduction but a marginal increase in nitrogen oxide emission is observed compared to neat diesel. The results showed that the MWCNT additives improved combustion efficiency and reduced emissions. This research contributes to the present understanding of nano-enhanced biodiesel fuels; this paper offers a paradigm shift in improving renewable energy sources for IC engines. Novelty is in the application of MWCNTs to enhance performance and stability of hemp biodiesel as a potential route toward cleaner and efficient formulations of biodiesel. [ABSTRACT FROM AUTHOR]

The shipping sector has been incorporated into the European Union Emissions Trading System (EU-ETS). Undoubtedly, the carbon emission factor is a critical consideration when determining carbon allowances in the EU-ETS, known as EU Allowances (EUAs). In this study, an all-performance carbon emission test was conducted on a marine LNG engine to investigate the differences between the actual carbon emission factor and the reference value. It was observed that the actual carbon emission factor is smaller than the reference value. The test results indicate a discrepancy of approximately 3%, resulting in potential savings of 10,000 to 20,000 dollars in EUAs for a ship consuming 2000 tonnes of LNG fuel annually. Furthermore, variations in the carbon emission factor were observed under different engine operational conditions, fluctuating by around 2% at constant revolutions per minute (RPM). This suggests the need for more suitable emission testing methods to accurately reflect actual emissions and better achieve emission control goals. • Differences of carbon emission factor between bench test and the reference value was analysed. • Cost reduction of EUAs based on the differences was analysed. • Carbon emission characteristics under all performance conditions were explored. • Carbon emission factor varies with operational conditions of the engines. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Explosives & Propellants is the property of Chinese Journal of Explosives & Propellants Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Precious Metals / Guijinshu is the property of Precious Metals Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Biofuel is an alternative fuel for diesel engines which is necessary to reduce exhaust emissions and helps to balance the depletion of fossil fuels. This study details the synthesis of bio-diesel and bio-oil from stone apple seeds (Aegle marmelos) through transesterification, direct oxygenate additive, and pyrolysis processes. The diesel engine is powered by the resulting stone apple methyl ester bio-diesel/diesel and bio-oil/diesel mixtures. In a test engine rig, the effectiveness and emission uniqueness of test fuel mixes were examined at various engine loads (EL = 3 kg–12 kg) and compression ratios (CR = 16–17.5) while maintaining a steady speed of 1500 r/min. Furthermore, engine performance and emissions for bio-diesel and bio-oil are measured and compared. The oxides of nitrogen (NOx) emission by bio-diesel and bio-oil opus were higher than neat diesel (FD). Also, carbon monoxide (CO) and hydrocarbon (HC) emissions were measured to be lower. The improvements of BTE by 4.87% and decrement of CO by 18.8%, HC by 13.26% were observed with the trans-esterified bio-diesel/diesel opus compared to diesel at a higher CR and rated load conditions. The engine analysis responses revealed that the FBD blend showed enhanced performance and lower emissions except NOx compared to diesel fuel. Hence, trans-esterified bio-diesel is a greater diesel alternative than FBDE and FBO. [ABSTRACT FROM AUTHOR]

Fault detection in marine diesel engine lubrication systems is crucial for ensuring the long-term stable operation of diesel engines and the safety of maritime navigation. Traditional fixed-parameter alarm threshold methods lack flexibility and are prone to missing faults. Data-driven approaches like machine learning require high-quality data for fault samples. This study leverages the relative advantages of data mining methods and threshold techniques, proposing an adaptive threshold construction method based on dynamic parameter relationship inference. Employing an algorithm for inferring dynamic relationships among multiple parameters of the lubrication system builds an adaptive threshold detection model. Extensive diesel engine tests and actual fault data demonstrate that the proposed method can address the issues of missed faults encountered by static threshold methods and the low detection accuracy of machine learning approaches without the need for fault samples. This significantly enhances fault detection accuracy in marine diesel engine lubrication systems, offering considerable industrial practical value. [ABSTRACT FROM AUTHOR]

This study explored the recovery of oil from lemon peel biomass and then tested it in a spark ignition as a substitute for gasoline. The study adopted the micro-arc oxidation coating technique, intending to improve the engine performance of the lemon peel oil-gasoline blends. The oil was recovered from discarded lemon peel biomass using steam distillation and then tested in the engine as a fuel by blending it with gasoline at volume ratios of 10, 20, and 30%. An endoscopic visualization approach was employed in this research work to assess the combustion initiation and flame characteristics of gasoline and lemon peel oil blends under different test conditions. Compared to gasoline and blends comprising 20 and 30% lemon peel oil, the 10% lemon peel oil mix produced higher thermal efficiency and lower emissions. The optical analysis demonstrated that premixed combustion with the 10% blend was found to be the highest, resulting in improved combustion and subsequently increased cylinder pressure. To improve the engine performance of the lemon peel oil blends with higher substitution (20 and 30%), the piston was coated with a ceramic coating. A novel technique, namely the micro-arc oxidation technique, was utilized for the coating. The coated piston engine fueled with a 20% lemon peel oil blend showed a 3% and 4.69% increase in thermal efficiency compared to the uncoated piston fueled with a 20% blend and sole gasoline, respectively. The hydrocarbon and carbon monoxide emissions of the engine with a coated piston fueled by the 20% lemon peel oil blend were reduced by 12.7% and 12%, respectively, as compared to gasoline operation in the engine with an uncoated piston. [ABSTRACT FROM AUTHOR]

This research is devoted to the development of a method for helicopter turboshaft engine energy characteristics control by regulating the free turbine rotor speed and fuel consumption using neural network technologies. A mathematical model was created that links the main rotor and free turbine rotor speed parameters, based on which a relation with the engine output power was established. In this research, a differential equation was obtained that links fuel consumption, output power, and rotor speed, which makes it possible to monitor engine dynamics in various operating modes. A fuel consumption controller was developed based on a neuro-fuzzy network that processes input data, including the desired and current rotor speed, which allows real-time adjustments to improve the operational efficiency. In the research, based on the flight data analysis obtained during the Mi-8MTV helicopter with a TV3-117 turboshaft engine flight test, improved signal processing quality was obtained due to time sampling and adaptive quantisation methods (this is confirmed by assessing the homogeneity and representativeness of the training and test datasets). A comparative analysis of the developed and traditional controllers showed that the neuro-fuzzy network use reduces the transient fuel consumption process time by 8.92% while increasing the accuracy and F1 score by 18.28% and 21.32%, respectively. [ABSTRACT FROM AUTHOR]

Combustion and emission characteristics of a heavy-duty single-cylinder ammonia engine with a hydrogen-fueled active pre-chamber ignition system are investigated experimentally at the condition of IMEP 10 bar, 1000 rpm, where effects of spark timing, excess air ratio (λ), and hydrogen energy ratio are tested. Three distinguishable combustion phases are observed, including pre-chamber combustion, turbulent-jet-controlled combustion, and ammonia-chemical-kinetics-controlled combustion. Advancing spark timing makes combustion phases earlier, increasing pressure rise rate, combustion pressure, and NOx emissions. The optimal spark timing for the highest indicated thermal efficiency (ITE) is −12°CA ATDC in the experiment. λ range for stable combustion is 1.1–1.5 and ITE peaks at λ = 1.3. The hydrogen energy ratio, 7.9%∼10.5%, has little influence on the engine performance. However, a low hydrogen energy ratio could increase the risk of misfire. The optimal hydrogen energy ratio is about 9∼10%. • The performance of a hydrogen-jet-ignited heavy-duty ammonia engine is tested. • Three-stage heat release of the hydrogen-jet-ignited ammonia engine is revealed. • Effects of spark timing, λ, and hydrogen energy ratio are uncovered. • λ range for stable combustion is 1.1–1.5 and ITE peaks at λ = 1.3. • The optimal hydrogen energy ratio is about 9–10%. [ABSTRACT FROM AUTHOR]

In this study, the characteristics of diesel engines were tested with in-house produced mahua biodiesel blended with diesel and copper oxide nanoparticles (CuO NP) catalyst. The preliminary investigation used mahua biodiesel-diesel blends (M10, M20, and M30) among them M20 outperformed. Further M20 and CuO NP with concentrations of 25, 50, and 75 ppm are studied. Finally, the response surface methodology (RSM) was used to determine the appropriate NP concentration for M20. The findings showed that the blend of M20 with 60 ppm NP at 80% load had the highest desirability (0.9740), and the developed RSM model predicted engine responses with a mean absolute percentage error (MAPE) of 3.0962% to the confirmation test confirming the model's accuracy. The optimized M20NP60 blend demonstrated superior combustion, performance and emission characteristics. [ABSTRACT FROM AUTHOR]

The widespread adoption of new technologies in aircraft engine testing has accelerated the development of free jet altitude test facilities, necessitating the study of simulations of aerodynamic characteristics. This study utilizes similarity dimensional analysis to construct a scaled model of a free jet altitude test facility. Computational fluid dynamics (CFD) methods are applied to examine the effects of nozzle deflection angle, flow rate, and exhaust diffuser diameter on aerodynamic parameters, such as intake effects, exhaust diffuser performance, and flow field characteristics. The findings reveal a negligible difference (less than 0.9%) in the characteristic parameters between actual atmospheric conditions and the scaled model when the nozzle deflection angle is set to 0° and −10° , enabling accurate atmospheric simulations. Additionally, the total pressure recovery coefficient at the engine inlet and the exhaust diffuser's efficiency exhibits opposing trends with varying exhaust diffuser diameters, suggesting that a balanced aerodynamic design of the inlet and exhaust systems is crucial for optimal performance. The exhaust diffuser's ejection coefficient increases with the nozzle's flow rate, indicating that optimizing the nozzle's flow rate within a specified range can significantly improve the exhaust diffuser's performance. [ABSTRACT FROM AUTHOR]

In the study at hand, a systemic investigation regarding the tribochemical effects of crankcase soot is presented. Sooted oils were generated via an engine dynamometer test. Both conventional as well as advanced oil condition monitoring methods indicated a mild degradation of additives. The wear volume was greatly increased with the sooted oils in model tribometer tests, despite the high residual zinc dialkyl dithiophosphate (ZDDP) antiwear (AW) levels. Once the soot was removed via ultracentrifugation, the wear volume returned to levels comparable to the fresh oil. Surface investigations revealed that ZDDP tribofilms could not form in the sooted oils, as only a thin sulfide layer was present on the metal surfaces. Meanwhile, typical tribofilms were observable with centrifuged oils. The results indicated that a tribocorrosive mechanism is most likely responsible for the elevated wear in the sooted oils, where only the iron sulfide base layer of ZDDP films is formed, which is then rapidly removed by the soot particles in an abrasive manner. [ABSTRACT FROM AUTHOR]

Bismuth (Bi) can be considered for use as a green substitute for lead in bearing applications. However, accelerated Bi oxidation can occur during operation, creating a brittle surface and resulting in premature seizure failure. Thus, the aim of this study was to evaluate the influence of engine oil degradation, especially nitration processes, on the oxidation of Bi. Tailor-made artificially aged oils with different degrees of nitration were produced and utilized in static bearing oxidation tests. By means of X-ray photoelectron spectroscopy (XPS), the Bi surfaces were analyzed regarding their chemical compositions after the tests. The results were correlated with the respective oil conditions determined via conventional parameters as well as high-resolution mass spectrometry. The findings obtained revealed a direct correlation between the amount of Bi-oxide and the nitration values of the oil, proving there was a positive impact of nitration products on the oxidation of the Bi surfaces. A comparison with the Bi content in the oils demonstrated a protective effect of the oxide layer as the Bi content declined with an increase in nitration. Overall, valuable insight into understanding the impact of oil condition on engine parts is given, and the importance of testing engine parts with aged lubricants is emphasized. [ABSTRACT FROM AUTHOR]

Gasoline combustion engine is generally the most important part of a car. With this driving unit the car achieves the best ratio between its fuel utilization and weight. In order to comply with required parameters, such as performance, ecology and economy of combustion engines, their regular service inspections and associated maintenance operations must be followed. For testing the operability of these engines, especially for testing the wear of functional pairs of the combustion chamber, we use various methods. The paper deals with detection of wear of combustion engine functional pairs and with subsequent comparison of obtained values with the values declared by the manufacturer. The measurements were carried out on a Suzuki gasoline engine G13BA with a cubature of 1298 cm3 and a total mileage of 160,000 km. [ABSTRACT FROM AUTHOR]

Aviation in Europe is required to use fuels containing up to 2 wt. % of sustainable aviation fuels (SAFs). A better understanding of the impact of SAFs on the combustion process will be helpful in solving problems that may arise from the widespread use of these kinds of fuels. It was assumed that the reactivity coefficient α i and the activation energy could be a criteria for assessing the impact of SAFs on the combustion process. Based on DGEN engine tests, the following activation energy values of C O 2 and C O formation reactions were obtained—Jet A-1: E a C O 2 / R = 3480 and E a C O / R = 982 ; A30: E a C O 2 / R = 3705 and E a C O / R = 2903 ; and H30: E a C O 2 / R = 3637 and E a C O / R = 2843 . These results indicate differences in the structure of combustion reaction chains involved by the SAF addition to Jet A-1 fuel. The same conclusion has been formulated on the basis of the reactivity coefficient αi. The values of maximum cylinder pressure (Pmax) obtained during indicator RCCM (rapid compression combustion machine) tests correlated with both the activation energy and coefficients of reactivity. This suggests that the influence of SAF addition to Jet A-1 fuel on the structure of chemical reactions chain during RCCM tests is similar to the influence during DGEN 380 tests. The assumption stated above was confirmed. This indicates the possibility of the preliminary forecasting of C O 2 and C O emissions from the DGEN 380 engine based on the test at the RCCM stand. [ABSTRACT FROM AUTHOR]

AbstractThe significant dynamic responses of helical springs are widely reported as the main reason causing pre-failure in various high-speed conditions. Though the concept of nonlinear springs is proposed to reduce their own dynamic responses, they are found to induce unexpected spike forces during operations. This study presents a dual springs system used within high-speed sports car engines, which aims to mitigate the dynamic responses and spike forces. Analytical models are first developed to calculate the fundamental frequencies of the outer and the inner springs of the system. Then, a transient finite element (FE) model is developed to accurately simulate the dual springs system working at various high engine speeds and validated experimentally by the results of the engine head tests. The simulations reveal that the use of dual springs with different natural frequencies can mitigate the dynamic responses of the whole system to a certain extent. Nevertheless, it is still a compromise as coil clash occurs on each isolated spring though the effects are reduced. The findings of this study indicate that the establishment of direct connections between every component spring would be a promising way to better mitigate the dynamic responses including the effects of coil clash. [ABSTRACT FROM AUTHOR]

Buses are crucial for urban public transportation systems as they help reduce traffic congestion and promote environmental sustainability. The noise inside buses significantly affects the comfort and physical health of both drivers and passengers. Although numerous studies have focused on the interior noise of buses, few have explicitly addressed the methods of reducing bus noise through comprehensive bus simulation and testing. Challenges of the full bus simulation include obtaining accurate engine vibration loads and building the finite element model of the full bus. This study presents a comprehensive approach for analyzing and optimization bus interior noise caused by engine vibration excitation. A novel hybrid method is proposed to identify bus engine vibration load, combining experimental testing of engine cylinder pressure with multibody dynamics simulation. Structure–acoustic coupled simulations were conducted to predict bus interior noise based on a detailed finite element model of the full bus. The study demonstrates a strong correlation between simulation and experimental results, validating the accuracy and effectiveness of the proposed method. The primary causes of the interior booming noise were identified by simulation analysis and experimental diagnosis. Optimization analysis led to a notable noise reduction by adjusting the support stiffness of the drive shaft, body structure, and integrating rear leaf spring dampers. These processes contribute to the analysis and improvement of bus interior noise, ultimately enhancing bus ride comfort and promoting sustainable urban public transportation. [ABSTRACT FROM AUTHOR]

The item under test was the engine without its standard facility-based cooling systems, the lack of which makes it impossible to operate as a power unit of a vehicle in a great majority of experimental research of internal combustion engines at high altitudes. The findings may create a wrong impression of the range of power ratings and economic parameters of the engine when operating at high altitudes because changes in atmospheric conditions exert an effect on the running efficiency of its standard systems as well. It is established that the efficiency loss of the cooling system may cause a forced power limitation of the engine as a result of the experimental research of the diesel engine equipped with all standard facility-based systems at very high altitudes. Thus, the shortage of power may significantly exceed the power loss of the engine due to air density reduction at high altitudes. [ABSTRACT FROM AUTHOR]

Solid ammonia dosing technology has been extensively researched in the last decade as an effective solution to address issues such as urea crystallization and carrier blockage in traditional selective catalyst reduction (SCR) systems. In this study, a comparison of nitrogen oxide (NOx) conversion efficiency between solid ammonia dosing (SAD) and Adblue dosing on a heavy-duty diesel engine SCR system was conducted. First, an engine emission test bench with SAD SCR and Adblue SCR systems was established. Subsequently, both dosing systems were tested and studied on the engine emission test rig. The results showed that the NOx conversion efficiency of SAD was slightly improved by approximately 2%–5% when the catalyst upstream temperature exceeded 250°C, compared with the Adblue system. This improvement can be attributed to the better mixing ability of SAD. Additionally, SAD demonstrated significant advantages in avoiding issues related to urea decomposition at low exhaust temperatures. Furthermore, similar results were observed in the emission cycle test results of the engine. Under the European steady-state cycle (ESC) and European transient cycle (ETC) conditions, the NOx conversion efficiency of SAD was only slightly higher than that of the Adblue system by about 2%. However, under the world harmonized transient cycle (WHTC) condition, where more low-temperature operating conditions are included, the beneficial weighted NOx conversion efficiency of SAD increased to approximately 7.4% at a release condition of 190°C. [ABSTRACT FROM AUTHOR]

Enhancing tribological performance through nanostructure control is crucial for saving energy and improving wear resistance for diverse applications. We introduce a new electrochemical approach that integrates aluminum (Al) anodization, tin alternating current (AC) electrodeposition, and anodic MoS2 electrosynthesis for fabricating nanostructured Al2O3/Sn(S)MoS2 composite films on AlSiCu casting alloys. Our unique process uses Sn‐modified MoS2 deposition to form robust solid lubricant MoS2–SnS electrodeposits within the nanochannels and microsized voids/defects of anodic alumina matrix films on the base materials, resulting in a bilayered Al2O3/SnSMoS2 and MoS2–SnS–Sn composite film. The AC‐deposited Sn enhances conductivity in the anodic alumina matrix film, acts as catalytic nuclei for Sn@SnS@MoS2 core‐shell nanoparticles and a dense top layer, and serves as a reductant for the direct synthesis of hybrid solid lubricant MoS2–SnS from MoS3 by anodic electrolysis of MoS42− ions. The resulting nanocomposite film provides a two‐fold increase in lubricity (friction coefficient (COF) μ = 0.14 ⇒ 0.07) and a ten‐fold improvement in wear resistance (COF μ < 0.2) compared to conventional Al2O3/MoS2 film formed by anodizing and reanodizing. The effectiveness of the Al2O3/Sn(S)MoS2 composite is further validated through real automotive engine piston tests. [ABSTRACT FROM AUTHOR]

The current study pertains performance optimization of multiple responses of a variable compression ratio diesel engine in regard to variation in load, compression ratio, and fuel type. A total of 9 number of experimental runs are performed as per the design of experiment suggested by Taguchi technique for three different load of 4 kg, 8 kg, and 12 kg, compression ratio of 14, 16, and 18, and fuel type of diesel, e-diesel (85% diesel and 15% bioethanol blend), and nano-fuel (85% diesel and 15% bioethanol blend with 25 ppm alumina nanoparticles). The bioethanol used in this study prepared from waste rice straw. The energy efficiency (η), exergy efficiency (ɛE), nitrogen oxide emission, and % relative cost variation are measured as output performances of this study. Fuel type has been identified as the most promising factor to energy efficiency, and exergy efficiency with a contribution of 41.1% and 64.53%, respectively. Load has been identified as the most promising factor to NOx emission, and % relative cost variation with a contribution of 71.69% and 34.92%, respectively. The compression ratio has been identified as the least contributing factor for all output performances. Nano-fuel attains higher sustainability index of 1.923 compared to other fuel due to lower depletion rate. Multiple output performance optimization has been carried out for maximum η, and ɛE, as well as minimum nitrogen oxide emission, and % relative cost using Taguchi–Grey technique. 19.37% enhancement in overall performance of the test engine is observed for determined optimal input parameters of 4 kg load, 18 compression ratio and nano-fuel. [ABSTRACT FROM AUTHOR]

Background: The aim of this research is to investigate the thermal behavior of a composite fuel prepared by mixing diesel fuel with citrus peel powder in the presence of activators and combustion accelerators. The study focused on utilizing abundant citrus waste, such as lemon and orange peels, as sustainable bioresources to reduce environmental pollution and optimize fuel efficiency. The research explored the thermal properties of the composite fuel and compared it with pure diesel through combustion experiments conducted at atmospheric pressure and combustion pressure in the engine. Methods: The study set the limits of the investigation to various proportions of lemon and orange peel powder mixed with diesel, ranging from 5% to 15% by mass of the total fuel composite. Two catalysts, sodium hydroxide (NaOH) and sulfuric acid (H2SO4), along with calcium oxide (CaO) powder were incorporated into the mixtures as activators to enhance combustion efficiency. The composite fuel characterization included thermogravimetric analysis (TGA) and thermographmetric station experiments to observe the combustion processes and assess the thermal behavior of the composite fuel. Results: The results revealed four distinct phases of combustion during the burning time of 60 seconds: volatile combustion, liquid combustion, combustion of solid materials, and the interaction of active substances with combustion residues. Using activators and catalysts significantly enhanced combustion efficiency and minimized the amount of residue produced during the process, resulting in thermal behavior that is more similar to that of pure diesel. Lemon peel powder with activators demonstrates better thermal behavior compared to orange peel powder. Conclusions: Based on the findings, some recommendations are proposed for further development such as the optimization of activator ratios, exploration of different proportions of lemon and orange peel powder, and investigation of other catalysts. Real-world engine performance tests and emission profile analysis can validate the thermal behavior results obtained from combustion experiments. [ABSTRACT FROM AUTHOR]

Fan blade icing can affect efficiency and aerodynamic stability, and the shed ice may be sucked into the core of the engine, causing adverse effects or even damage to the compressor components. Ice accretion and shedding are among the key issues in engine design and tests. But they have not been clearly understood. In this work, ice shedding from rotating aero-engine fan blades during continuous icing is experimentally investigated under the relevant airworthiness requirements. The phenomena of icing and ice shedding under different ambient temperatures and engine speeds are recorded to obtain the ice-shedding time and the characteristic length of the residual ice. Force analysis is used to understand the corresponding behavior. The degree of ice-shedding balance D b is defined to explore the symmetry of ice shedding. The results show that the shedding time is significantly affected by the rotational speed, and the characteristic length will first shorten and then grow as the ambient temperature decreases. When the ice shedding is completed instantaneously, D b will show a violent shock. There is a critical ambient temperature, below which the ice accretion will worsen significantly as temperature decreases. For aero-engine fan blade icing tests during ground idle, the critical ambient temperature ranges from − 5   ∘ C to − 9   ∘ C. In order for the ice to shed faster, the engine speed has to reach a threshold. This study can shed light on the preliminary characteristics of ice shedding from rotating components and provide guidance and a data basis for the numerical simulation of fan blade icing and the design of an aero-engine. [ABSTRACT FROM AUTHOR]

Most of the vehicles used by Malaysians have engines that only require petrol RON 95 to power the engine. However, many people claimed that utilising RON 100 instead of RON 95 for their vehicles will improve engine performance. Furthermore, many people speculate that using oil with a low octane level in an engine with low performance will affect the engine's performance. The goal of this research is to analyse and compare the engine performance and emissions on a spark ignition engine using gasoline RON 95 and RON 100. In this study, a single-cylinder four-stroke engine running with RON 95 and RON 100 has been tested on an engine dynamometer to evaluate the brake power, torque, specific fuel consumption, and exhaust emissions. The emissions from the engines have been determined using a gas emissions analyser. The outcomes of the experiment have been analysed based on engine torque, braking power, and exhaust emissions. Based on the analysis, torque, brake power, and emissions data obtained from the dynamometer engine, RON 100 has a higher and smoother performance than RON 95. [ABSTRACT FROM AUTHOR]

Safe shutdown of a liquid rocket engine in ground testing prior to the onset of damaging combustion instabilities through reliable detection of instability precursors would translate to time and cost savings in engine development programmes. Methods derived from statistical, recurrence, and fractal analysis have been successfully applied in the literature to detect precursors in unsteady pressure signals from canonical combustion experiments, gas-turbine combustion experiments, and sub-scale rocket combustion experiments operated at low pressures. In the present work, several such methods were applied to data from two cryogenic oxygen-natural gas rocket experiments operated at higher pressures than previously reported; both sub- and supercritical with respect to oxygen. The goal was to identify methods that can discern limit-cycle instabilities from intermittently unstable operation and are sufficiently responsive to be applied as emergency shut-down criteria in engine tests. Among the methods applied were the standard deviation, variance of the auto-correlation, the second spectral moment, the ratio between determinism and recurrence rate, the Hurst-exponent, and the multifractal range. The second spectral moment, the Hurst-exponent, and a measure derived from the multifractal spectrum all have short detection delays for instability onset and short-lived could be discerned from self-sustaining instabilities with an appropriate choice of threshold value. They also have moderate computation cost which makes them of interest for potential real-time implementation. The Hurst-exponent has the additional advantage of a common threshold value for all test cases addressed, demonstrating its potential for broader application independent of combustion device or operating conditions. [ABSTRACT FROM AUTHOR]

This study aims to investigate the engine performance of spark-ignition engines with port fuel injection using E50 fuel, which contains 50% gasoline or pertalite (in Indonesia) and 50% hydrate bioethanol, at airfuel ratio variations of 10:1, 12:1, and 14:1. The experiments were conducted using a 1-cylinder, 662 cc engine research test with a constant load of 3 kg and engine speed variations of 1500 and 1800 RPM, as well as a compression ratio of 10:1 and standard ignition timing. The engine ran with E50 fuel, and the experimental results were compared with those of E0 for an air-fuel ratio of 14:1. According to the data, the fuel energy of E50 in an AFR of 14:1 is 0.11 kW higher than that of E0, and it increases by 21.6% when the engine speed increases from 1500 to 1800 RPM. The results also indicate that the efficiency of all performance indicators, such as indicative thermal efficiency, brake thermal efficiency, and mechanical efficiency, is maximized when the engine is operated at an AFR of 10:1 for E50 fuel. Additionally, the volumetric efficiency of E50 reaches its maximum when the fuel is burned at an AFR of 14:1, and it increases as the engine speed increases. However, it should be noted that the brake power decreases due to the frictional power of the fuel increase. [ABSTRACT FROM AUTHOR]

The preliminary objective of the present work is to evaluate the performance and emission characteristics for different CR and engine loads using diesel and Moringa oleifera biodiesel blends as fuel. In the present work mono cylinder, 4-stroke, CRDI-VCR type, CI engine tested using diesel and Moringa oleifera biodiesel blend MB10, MB20, and MB30to investigate the performance and emission behavior of an engine concerning CR at the different loading conditions (0.88, 1.75, 2.66 and 3.5 kW). The experiment was performed at four different CRs 15:1, 16:1, 17:1, and 18:1 at fixed IT 23°bTDCand IP 600 bar. The results of the experiment show that the highest BTE for diesel and biodiesel blend MB30 is reported at 27.26% and 28.26% at the higher CR of the present investigation 18:1 and 100% load condition. The increase in load and CR shows the reduction in the BSFC and BSEC of an engine for all tested fuels and the minimum BSFC and BSEC reported among the entire fuel blend is 0.30 kg/kWh and 12.9 MJ/kWh for MB30 fuel blend at higher CR of present investigation 18:1 and 100% load condition. The minimum emission of CO and HC reported for MB30 fuel at higher CR of present investigation 18:1 and 100% load condition is 0.04 % vol and 8 ppm. In the present investigation, the highest CR of 18:1 and 100% load condition offers the minimum emission of NOx reported as 522 ppm for the biodiesel blend MB20 among entire fuel blends. The results reveal that the NOx emission of the MB20 fuel blend is about 11.97% less than recorded for diesel. The emission of smoke is almost zero for all the fuel blends at the higher CR 17:1 and 18:1 up to 50% loading condition. The highest emission of smoke was observed at lower CR 15:1 and 100% loading conditions for all the tested fuel blends. Moringa oleifera biodiesel blend MB30 shows an enhancement in thermal performance by increasing BTE and decreasing BSFC while improving emission characteristics by reducing emissions of pollutants such as CO, HC, smoke, and NOx. [ABSTRACT FROM AUTHOR]

The conventional fuel used to produce electrical energy and the burning of the conventional fuel causes global warming. Also, there is a depletion of these fuel and hence there is a need of alternative fuels. The biodiesel is a renewable fuel and it is a sustainable fuel. The biodiesel can be derived from waste cooking oil (WCO) as it increases the commercial value of the WCO. The biodiesel has lower oxidation stability and hence onion oil which has good anti oxidation value was added with WCO biodiesel. The engine tests were carried with WCO biodiesel added with onion oil shows that the addition of onion oil improves the thermal efficiency and improvement in cylinder pressure and heat release rate. We conclude that the onion oil can be used as additive to the WCO biodiesel. [ABSTRACT FROM AUTHOR]

The OpenFOAM computational fluid dynamics code was used to investigate the performance characteristics of spray jet in a constant volume combustion bomb. The total duration of fuel spray was approximately $$1.25 \times {10^{ - 3}}$$ 1.25 × 10 − 3 second, and the total mass of fuel sprayed was $$6.0 \times {10^{ - 6}}$$ 6.0 × 10 − 6 kilogram. The results show that there was a positive and somewhat positive qualitative correlation between the profiles of the number of parcels and the mass flow rate of the injected fuel at between $$0 \le t\le 4.4 \times {10^{ - 4}}$$ 0 ≤ t ≤ 4.4 × 10 − 4 second. Furthermore, at between $$9.1 \times {10^{ - 4}} \le t\le 1.3 \times {10^{ - 3}}$$ 9.1 × 10 − 4 ≤ t ≤ 1.3 × 10 − 3 the number of parcels experienced a sharp rise while the injected mass flow rate was decreasing, see Figure 6. The results of the present study show that the spray droplet sizes vary from $$0.25 \mum$$ 0.25 \mum to $$150 \mum$$ 150 \mum which were found to be reasonably representative of measurement data that are usually observed at the top dead centre position of internal combustion engine test bed experiments. Furthermore, the results of the study show the contour plots of pressure and temperature. The pressure rise varies from the initial value of 50 bar to 75 bar at the end of combustion while the temperature rose from $$550^\circ K$$ 550 ∘ K to its final value of $$2800^\circ K$$ 2800 ∘ K. The specific details of the results from this study are summarised in the conclusion section. [ABSTRACT FROM AUTHOR]

The increasing number of software applications incorporating machine learning (ML) solutions has led to the need for testing techniques. However, testing ML software requires tremendous human effort to design realistic and relevant test inputs and to judge software output correctness according to human common sense. Even when misbehavior is exposed, it is often unclear whether the defect is inside ML API or the surrounding code and how to fix the implementation. This article tackles these challenges by proposing Keeper, an automated testing and fixing tool for ML software. The core idea of Keeper is designing pseudo-inverse functions that semantically reverse the corresponding ML task in an empirical way and proxy common human judgment of real-world data. It incorporates these functions into a symbolic execution engine to generate tests. Keeper also detects code smells that degrade software performance. Once misbehavior is exposed, Keeper attempts to change how ML APIs are used to alleviate the misbehavior. Our evaluation on a variety of applications shows that Keeper greatly improves branch coverage, while identifying 74 previously unknown failures and 19 code smells from 56 out of 104 applications. Our user studies show that 78% of end-users and 95% of developers agree with Keeper's detection and fixing results. [ABSTRACT FROM AUTHOR]

Assessment of alternate fuel is categorized on thermophysical aspects and performance—emission derived due to its combustion. Data derived from such analysis is short as the energy expenditure to available chemical exergy of fuel is rarely studied. The study of energy derived from fuel energy gives a detailed picture of fuel efficiency and broadens the field of fuel search criteria. The current article aims to find the thermodynamic effects in terms of energy and exergy utilization of neem biodiesel blends and nickel oxide nano additive dosed neem biodiesel blends. Neem biodiesel was transesterified using standard procedures and analyzed using gas chromatography and mass spectroscopy. Later, neem biodiesel was blended with diesel in three volumetric proportions, that is, NB25, NB50, NB75, and pure Neem Oil Methyl ester was investigated as an engine fuel, and later synthesized nickel oxide nano additives of 25 mg/L was added to all the above fuels and further studied for energy, exergy utilization on a TV‐1 VCR engine test rig under varying engine CR. Nickel oxide additives were manufactured using homogenous addition method and were thoroughly studied for formation and presence of constituents using XRD, FE‐SEM, and EDS methods. The usage of nano additives does prove reduction in exergy destruction and entropy generation for NB25 base blend with 25 mg/L NiO leading to a reduction of 8.2% and 9.7% when compared to base blends. Also, the emission found for hydrocarbon, and carbon monoxide for all base fuel blends reduced by an average of 16.8% and 7.35%. [ABSTRACT FROM AUTHOR]

Sensors are crucial for measuring combustion temperatures in aerospace and aviation engine testing. However, current sensors have poor oxidation resistance, low impact resistance, limited lifespan, and inadequate temperature measurement accuracy, often resulting in unsatisfactory testing outcomes. New sensor designs are urgently needed to address these issues. We propose a new sensor with advanced materials and technologies, based on the principle of ultrasonic guided wave temperature measurement with magnesium aluminum spinel (MgAl2O4) and magnesium-doped aluminum oxide crystals as ultrasonic waveguides.The design parameters of this sensor’s sensitive elements were meticulously crafted. Finite element method simulations were then conducted to assess the impact of groove depth on ultrasonic propagation characteristics. Ultrasonic temperature sensors with spinel and magnesiumdoped aluminum oxide were fabricated via the laser heated pedestal growth method. These sensors were calibrated in an oxidative environment, demonstrating a temperature sensitivity of 0.48 m/s·°C and a repeatability of 95% across a range from 20 °C to 1600 °C. By comparison among the three materials at a constant temperature, the sound velocity of sapphire was the fastest, followed by magnesia-doped alumina, while magnesia-alumina spinel was slowest. Thus, magnesia-alumina spinel can be considered an effective acoustic waveguide material for facile signal acquisition and hightemperature resolution. The proposed sensor design shows promise for applications in environments prone to oxidative erosion and high temperatures, offering an innovative solution for reliable temperature measurement within the harsh environments of aerospace and aviation engines. [ABSTRACT FROM AUTHOR]

This study developed a fibre-optic laser Doppler velocimetry sensor for use in opaque, high-temperature, and high-pressure fluid flows by inserting the fibre perpendicular to the main flow. The tip of the optical fibre was obliquely polished and chemically etched using a buffered hydrofluoric acid solution, and a reflective mirror was deposited on the surface of the oblique fibre tip. Based on the results of the verification test using the rotating annular open channel, the fabrication conditions of the fibre tip were optimized for measuring the lubricating oil flow. The flow velocity profiles in the engine's oil flow of the lubrication system during engine bench testing were measured. These velocity profiles were influenced by variations in the measurement position, oil temperature, and engine speed. The measurement accuracy of this sensor was compared with the volumetric flow rate obtained by cross-sectional area integration of the flow velocity profile, as measured using a Coriolis flowmeter, and the difference was within 1%. By combining computational simulation for flow and optical attenuation and particle scattering in light transmission through a working fluid, this fibre-optic sensor achieved a measurement volume of 200 microns in length and 200 microns in width at a distance of 900–1000 microns from the sensor. [ABSTRACT FROM AUTHOR]

According to the characteristics of the rotor system in an aero-engine and the vibrational test requirements of the aero-engine ground test, suitable vibration measurement sensors and test positions were selected. The vibration signals at the casings for the compressor and turbine of a twin-spool turbo-jet engine were collected under the states of maximum power and afterburning respectively, and the power spectrum analysis was carried out to determine the positions and causes of vibration. Furthermore, methods and preventive measures for eliminating vibration have been proposed. The results indicated that the main rotor vibration excited by mass imbalance in the twin-spool turbo-jet engine was significant. Rotor spindle misalignment or rotor radial stiffness unevenness also induced the vibration. The aerodynamic pulse vibration formed by the rotor blades of the first stage of the low pressure compressor was large, and rub induced vibration fault may occur at the turbine rotor seals. Based on the power spectrum analysis technology, the rotor system faults information including the type, position, and the degree can be quickly identified, and useful attempts and explorations have been made to reduce the vibration faults of the twin-spool turbo-jet engine. [ABSTRACT FROM AUTHOR]