Cylinder Head Temperature Research Articles

Thermal Monitoring of an Internal Combustion Engine for Lightweight Fixed-Wing UAV Integrating PSO-Based Modelling with Condition-Based Extended Kalman Filter

The internal combustion engines of long-endurance UAVs are optimized for cruises, so they are prone to overheating during climbs, when power requests increase. To counteract the phenomenon, step-climb maneuvering is typically operated, but the intermittent high-power requests generate repeated heating–cooling cycles, which, over multiple missions, may promote thermal fatigue, performance degradation, and failure. This paper deals with the development of a model-based monitoring of the cylinder head temperature of the two-stroke engine employed in a lightweight fixed-wing long-endurance UAV, which combines a 0D thermal model derived from physical first principles with an extended Kalman filter capable to estimate the head temperature under degraded conditions. The parameters of the dynamic model, referred to as nominal condition, are defined through a particle-swarm optimization, minimizing the mean square temperature error between simulated and experimental flight data (obtaining mean and peak errors lower than 3% and 10%, respectively). The validated model is used in a so-called condition-based extended Kalman filter, which differs from a conventional one for a correction term in section prediction, leveraged as degradation symptom, based on the deviation of the model-state derivative with respect to the actual measurement. The monitoring algorithm, being executable in real-time and capable of identifying incipient degradations of the thermal flow, demonstrates applicability for online diagnostics and predictive maintenance purposes.

Multi-modal LSTM network for anomaly prediction in piston engine aircraft

An aircraft is a highly intricate system that features numerous subsystems, assemblies, and individual components for which regular maintenance is inevitable. The operational efficiency of an aircraft can be maximised, and its maintenance needs can be reduced using an effective yet automatic AI-based health monitoring systems which are more efficient as compared to designing and constructing expensive and harder to operate engine testbeds. It has been observed that aircraft engine anomalies such as undergoing flameouts can occur due to the rapid change in the temperature of the engine. Engine oil temperature and cylinder head temperature, two measures connected to this issue, might be affected differently depending on flight modes and operational conditions which in turn hamper AI-based algorithms to yield accurate prediction on engine failures. In general, previous studies lack comprehensive analysis on anomaly prediction in piston engine aircraft using modern machine learning solutions. Furthermore, abrupt variation in aircraft sensors' data and noise result in either overfitting or unfavourable performance by such techniques. This work aims at studying conventional machine learning and deep learning models to foretell the possibility of engine flameout using engine oil and cylinder head temperatures of a widely used Textron Lycoming IO-540 six-cylinder piston engine. This is achieved through pre-processing the data extracted from the aircraft's real-time flight data recorder followed by prediction using specially designed multi-modal regularised Long Short-Term Memory network to enhance generalisation and avoid overfitting on highly variable data. The proposed architecture yields improved results with root mean square error of 0.55 and 3.20 on cylinder head and engine oil temperatures respectively averaged over three case studies of five different flights. These scores are significantly better i.e., up to 84% as compared to other popular machine learning predictive approaches including Random Forest, Decision Tree Regression, Artificial Neural Networks and vanilla Long Short-Term Memory networks. Through performance evaluation, it can be established that the proposed system is capable of predicting engine flameout 2 minutes ahead and is suitable for integration with the software system of aircraft's engine control unit.

Study of the periodic thermal contact between exhaust valve and its seat in an internal combustion engine

The focus of internal combustion engine development for urban vehicles is shifting towards reducing materials by making them lighter. In order to maintain thermal and flow levels, a model was developed to study the thermal behavior of valve seats during periodic contact, which can also help improve engine performance and fuel efficiency. The model, composed of two cylindrical bars in periodic contact, takes into account the evolution and topography of the contact surface. The model's performance was evaluated through various experimental studies and showed a maximum difference of 5.05% with experimental values, in good agreement with previous literature. The results showed that heat flux increases with increasing contact frequency and thermal diffusivity affects conductive transfer. This model can be used by manufacturers to evaluate cylinder head temperature and by the automotive industry to improve heat transfer in engines.

Design and Analysis of UAV Test Bench for Engine/Motor Characterization

A thrust test bench is an instrument which can measure the Thrust, Rpm, Power, Torque, Temperature Explicitly etc. This is composed of the test bench architecture attached to the motor or the engine through the rotating shaft. An absorber being attached to the engine means nothing but an extra component which drives the energy of the motor, that is a propeller if assumed. The main objective here is to design a Test Bench which can maximum hold the weight of UAV Engines or motors within 15kgs and to conduct Structural Finite Element Analysis on different parts of the test bench to determine the stress behaviour. The parameters which the test bench can measure are Thrust, Velocity, Rotational Speed, Torque, Cylinder Head Temperature, Exhaust Temperature etc. This is achieved by using certain sensors introduced with a DAQ system for precise and accurate measurements of the parameters.

Correlations for the Performance, Efficiency, and Energy Losses for Single Cylinder, Four-Cycle Internal Combustion Engines With Displaced Volumes Ranging From 40 to 200 cc

AbstractFive commercial-off-the-shelf (COTS) engines ranging from 40 to 200 cc were tested as potential power plants for Group Two RPAs. The maximum brake power ranged from 1.8 to 5.0 kW. Of the five engines, two were designed for hobby aircraft (similar in size to Group Two RPAs) while the other three were designed for powered equipment applications. These five engines were run at WOT through their respective operating speed ranges to develop energy balances, specifically quantifying the split of energy between brake power, cooling load, exhaust enthalpy, and incomplete combustion. Using the energy balance data, general correlations for BMEP and fuel conversion efficiency as functions of displaced volume were generated to compare with previous two stroke engine results. Furthermore parametric studies capturing the effects of throttle setting, combustion phasing, cylinder head temperature, and equivalence ratio on the peak BMEP and fuel conversion efficiency were performed. The study data was used to develop normalized correlations to predict peak brake power, incomplete combustion, exhaust enthalpy, and cooling load as normalized deltas from the baseline condition. These correlations can be used to help engine designers understand the effect of these parameters for four stroke engines in the size class of 40–200 cc.

Assessment of antioxidant impact on fuel stability and emission personality for Alexandrian laurel and Poison nut biodiesel

The chief criterion for non commercialization of biodiesel is the unbalanced fuel properties and poisonous NOx emission level in elevated quantity. But in the case of marketable petrol and diesel fuels, the fuel properties are in much steady state leading to extended fuel stability without putrefying in fuel properties and lower NOx emission level. The difference between the stability capacities is the reaction of fuels to the atmospheric oxygen. Obviously biodiesel contains oxygen content in superior quantity, as the feedstock is the naturally available resources when compared to fossil fuels. The present attempt has been focused to stable the fuel properties by evaluating the oxidation, storage and thermal stability of Alexandrian laurel and Poison nut biodiesel with the assist of Tert-butyl hydroquinone antioxidant at 1000 ppm, in the subsequent ratios as AP10T, AP15T, AP20T, AP25T and AP30T using high-tech equipments. FTIR infers the stability variation with the aid of C–H and O–H bonds in the fuel blends. In adding up with that, the relationship between NOx emission and cylinder head temperature has been made through novel Fluke thermal imager. As a result, AP20T shows supreme fuel stability and NOx emission nearer to commercial diesel fuel.

Effect of key parameters on knock suppression in a two-stroke spark ignition engine with aviation kerosene fuel

This research work studies the impact of the mixture concentration, spark timing, and ignition energy on the knock suppression of a two-stroke spark ignition aviation kerosene-fueled engine. Bench tests on different working conditions were conducted and some related data including in-cylinder pressure, cylinder head temperature, exhaust temperature, engine power, and torque were collected to analyze the influence of different control parameters on the knock characteristics of the engine. The results show that the knock can be suppressed at leaner and richer (than the stoichiometric) mixtures, and the richer mixture has a more obvious effect on suppressing knock. Retarding the ignition advanced angle will reduce the knock intensity but will make the exhausted temperature exceed and the output power decrease. The use of a rich mixture with early spark timing has a better effect on the knock suppression as compared to the use of a lean mixture with late spark timing. Reducing the ignition energy can suppress the knock slightly, but experimental results show that it is not an effective way.

Research on energy distributions of the lateral swirl combustion system in DI diesel engines

The lateral swirl combustion system (LSCS) can improve the air-use, fuel and emission performance of direct injection (DI) diesel engines. In this study, the differences in energy distributions between the LSCS and the double swirl combustion system (DSCS) were analyzed under different working conditions using a single-cylinder test system. A simulation calculation was used to compare the velocity, mixture equivalence ratio and in-cylinder temperature distributions of the working medium in the two combustion chambers, elucidating the different energy distributions of the two chambers. Additionally, a new idea is proposed herein for the design of LHR engines. The experimental results show that, compared with the DSCS under different operating speeds (1300–2100 r/min) and different loads (21–43 kW), the indicated thermal efficiency of the LSCS was approximately 2% higher, the percentage of the exhaust energy and heat transfer to the total energy was approximately 2% lower, the cylinder head temperature was 2–20.5 K lower, the ratio of the cylinder head heat transfer to the total heat transfer was 2–8% smaller and the heat transferred to the cooling water in the water jacket of the cylinder head was 0.2–1 kW lower. The in-cylinder velocity distribution, mixture equivalence ratio and temperature distribution of both the LSCS and the DSCS were compared through simulation. The results show that the fuel in the LSCS developed along the wall of the combustion chamber circumferentially due to the convex edge, and the high temperature zone distributed along the circumference of the combustion chamber. In the DSCS, most of the fuel moved to the cylinder head due to the circular ridge, and the high temperature zone existed near the cylinder head. The LSCS had a lower cylinder head temperature, a higher exhaust gas temperature, and less heat transferred to the cooling water through the cylinder head. Therefore, the unique shape of the LSCS chamber guided the movement of the fuel and reduced the concentration of the fuel/air mixture near the cylinder head, which reduced the heat transferred to the cooling system through the cylinder head and improved the thermal efficiency. In addition to these findings, this study also provides a foundation for the design of a low heat rejection engine.

Thermal Characteristics Investigation of the Internal Combustion Engine Cooling-Combustion System Using Thermal Boundary Dynamic Coupling Method and Experimental Verification

The engine cooling system must be able to match up with the stable operating conditions so as to guarantee the engine performance. On the working cycle level, however, the dynamic thermo-state of engines has not been considered in the cooling strategy. Besides, the frequent over-cooling boiling inside the gallery changes the cooling capacity constantly. It is necessary to study the coupling effect caused by the interaction of cooling flow and in-cylinder combustion so as to provide details of the dynamic control of cooling systems. To this end, this study develops a coupled modeling scheme of the cooling process considering the interaction of combustion and coolant flow. The global reaction mechanism is used for the combustion process and the multiphase flow method is employed to simulate the coolant flow considering the wall boiling and the interphase forces. The two sub-models exchange information of in-cylinder temperature, heat transfer coefficient, and wall temperature to achieve the coupled computation. The proposed modeling process is verified through the measured diesel engine power, in-cylinder pressure, and fire surface temperature of cylinder head. Then the effects of different cooling conditions on the cyclic engine performances are analyzed and discussed.

Energy Balance and Power Loss Pathway Study of a 120 cc Four-Stroke Internal Combustion Engine

Efforts to improve the range and endurance of group 2 (10–25 kg), internal combustion engine (ICE) powered unmanned aerial vehicles (UAVs) have been underway for several years at Air Force Research Laboratory (AFRL). To obtain the desired performance improvements, research into improving the overall efficiency of the ICE powerplants is of great interest. The high specific energy of hydrocarbon fuels (13,000 W h/kg for gasoline), but low fuel conversion efficiency for small ICEs means that relatively minor improvements in the fuel conversion efficiency of the engines can yield large improvements in range and endurance. Little information is available however for the efficiency of ICEs in the size range of interest (10–200 cm3 displacement volume) for group 2 UAVs. Most of the currently available efficiency data for 10–200 cm3 ICEs is for two-stroke engines. The goal of this study was to provide an in-depth probe of the efficiency and energy losses of a small displacement four-stroke engine which could potentially be used to power a group 2 UAV. Energy balances were performed on a Honda GX120 four-stroke engine using empirical research methods. The engine was a 118 cm3 displacement, single cylinder ICE. Energy pathways were characterized as a percentage of the total chemical energy available in the fuel. Energy pathways were characterized into four categories: brake power, cooling load, exhaust sensible enthalpy and incomplete combustion. The effect of five operating parameters was examined in the study. Fuel conversion efficiency ranged from 22.2% to 25.8% as engine speed was swept from 2000 to 3600 RPM, from 20.8% to 27.3% as equivalence ratio was swept from 0.85 to 1.25, and from 15.7% to 24.9% as throttle was swept from 28.5% to 100%. Combustion phasing and cylinder head temperature sweeps showed only minor changes in fuel conversion efficiency.

Effect of Fire-Deck Thickness on thermal status of cylinder head

In this paper, different value of fire-deck thickness on temperature, thermal stress and low cycle fatigue (LCF) life of cylinder head has been discussed and investigated. A 6-cylinder engine has been selected for CFD and thermal analysis. And a half model (3-cylinder) has been used for the stress and corresponding LCF calculation because of the identical structure among cylinders. The thermal condition of cylinder head is calculated with the conjugate heat transfer (CHT) simulation between cylinder head and coolant. The results shows that temperature variation among different cylinders is tiny. With the fire-deck thickness (FDT) increased, the temperature and thermal stress on cylinder head fire-face raised apparently, while the LCF life is reduced. When the FDT increases from 9 to 13, the thermal stress, peak and average temperature on cylinder head fire face is increased by 10.85%, 5.89% and 4.76%, respectively. The corresponding LCF life is reduced from 9875 to 5730 times.

Research on air diversion channel of air-cooled gasoline engine cylinder head and simulation of fluid- solid coupling heat transfer

In view of the problem that local temperature of the original cylinder head is on the high side, an innovative cooling air diversion channel is proposed. The cooling air diversion channel introduces cool air into the cylinder head to forcedly cool the cylinder head. Furthermore, the multiple guide plates are set to reasonably distribute cold air in the air diversion channel. In addition, appropriately increase the length of the fins to cooling the whole cylinder head. The fluid-solid coupling three-dimensional simulation technology is adopted to analyze the impact of the new air diversion channel on the heat dissipation of cylinder head. Finally, the optimal scheme is defined to fabricate the prototype. Simulations results show that the above improvements make the temperature in the high temperature region effectively decrease, and the cooling performance of whole cylinder head is enhanced. In the optimal improvement scheme, the highest temperature of cylinder head decrease by 23 K. Furthermore, the prototype was fabricated according to the optimal scheme. The experimental results show that the temperature of the improved cylinder head decreased effectively, and the highest temperature decreased by 20.4 K. The simulation results are in agreement with the experimental results, and the maximum error is less than 5 percent.

SIMULATION MODELING OF FUZZY LOGIC CONTROLLER FOR AIRCRAFT ENGINES

This article described project of fuzzy logic controller witch control the scope of opening cowl flaps in Piper Seneca V engines. This allows to maintain optimum engine temperature by varying the amount of air flow through the engine compartment. The main task of controller is to reduce pilot workload during the entire flight, as well as to maintain optimum engine operating parameters in order to increase its service life. The designed fuzzy controller generates a cowl flaps control signal according to the three most important input parameters: Cylinder Head Temperature (CHT), Vertical Speed Indicator (VSI), Manifold Pressure (MP). The project uses Matlab and Fuzzy Logic Toolbox software. The authors presented the performance of the system based on twenty samples for research, which simulate position flaps. This articles presented also control surfaces, due to which it is possible to analyze controller performance. At the end showed the simulation process in the Simulink software package with the preset input values.

Method for assessing the changes of the thermal state of cylinder head of engine with air-cooling when boosting

The diesel engines with air-cooling have lower than engines with liquid cooling values of the average effective pressure. This happens because of lower stiffness of body parts of air-cooled diesel engines and the difficulty of maintaining within acceptable limits the temperature of the parts of the cylinder group when increasing power. Most heat-stressed elements of the design of the air-cooled diesel are cylinders heads. When boosting diesel with supercharge the question arises about possible limits of increasing boost pressure and the required depth of the charge of air cooling, where the cylinder head temperatures do not exceed the permissible limits. Predictive calculation at various levels of boosting the temperature fields in the cylinders heads by solving the heat equation through numerical methods faces the problem of determining with sufficient accuracy of the boundary conditions, primarily from the side of the cooling air. For air-cooled diesel engines ready or prepared for production is typically conducted the thermometering of cylinders heads defining, inter alia, the temperature value at the head surface at the bottom in most heat-stressed zones. A method for estimating changes in the thermal state of the head cylinder of engine with air-cooling when boosting, based on using data of testing and thermometering of diesel with initial level of boosting, is proposed. The method allows to set the limits of the possible boosting at various adjustments of diesel. The effectiveness of the method is confirmed by an example calculation for tractor diesel 8ChVN15/16. Comparison of the results of calculation of the maximum temperature value of cylinder head bottom with experimental data indicates that the values differ by no more than 1.8%. The proposed method correctly predicts the change of the thermal state of the cylinder head when boosting diesel with air-cooling by supercharge and can be used in engineering practice to assess the possible limits of boosting such diesels, choosing adjustments of fuel handling and parameters of coolant of charging air.

THE ESTIMATION OF CARBON DEPOSIT INFLUENCE ON THE TEMPERATURE STATE OF THE MIDDLE SPEED DIESEL CYLINDER HEAD

Conception of cylinder head fractures origin in the locomotive diesels is expanded. The carbon deposit influence on the cylinder head temperature state is estimated. The nonuniform heat flux distribution is studied. Carbon layer presents on the fourstroke locomotive diesel cylinder head surface considering during its temperature state simulation is performed.

Monitoring diesel engine parameters based on FBG probe

This paper proposes an unprecedented systematic approach for real-time monitoring the temperature and flow of diesel engine by using embedded fiber Bragg grating (FBG). By virtue of FBG’s temperature effect, we design a novel sensitive FBG temperature sensing probe to measure the temperature of cylinder head and inlet flow of diesel engine. We also establish the corresponding software platform for intuitive data analysis. The experimental and complementary simulation results simultaneously demonstrate that the FBG-based optical fiber technique possesses extraordinary reproducibility and sensitivity, which makes it feasible to monitor the temperature and inlet flow of diesel engine. Our work can provide an effective way to evaluate the thermal load of cylinder head in diesel engine.

Effects of cylinder head temperature and coolant velocity on the erosion behavior of water jacket in a diesel engine

Effects of surface temperatures and coolant velocities on the erosion behavior of the engine water jacket was investigated in a test bench, which was designed to provide similar conditions to the water jacket in an engine. Rectangular specimens were fabricated using the water jacket material (aluminum alloy A356T5), then installed in the test bench and heated using fire torches. To evaluate the effects of two parameters, high speed camera, scanning electron microscope (SEM), mass scale, energy dispersive spectroscopy (EDS) were used. If any pits appeared as a result of erosion, the pit size growth rates were calculated. In addition, the single bubble collapse pressure was calculated using an erosion model to quantify the interaction between the bubble and the solid surface. It was found that higher mass reduction and surface changes appear under the condition of the higher surface temperature and the faster coolant velocity. Surface temperature affected the bubble and pit formation, while, the coolant velocity influenced the overall trend of mass reduction. As a result of calculation, the single bubble collapse pressure was order of 109Pa. Detailed effects of two parameters on erosion behavior are discussed.

Engine Cylinder Head Temperature Measurement Based on Optical Fiber Probe

Abstract A method of investigating engine cylinder head temperature is presented in this paper that uses an embedded fiber Bragg grating (FBG) with the least modification and intrusion on its operation. The temperature of cylinder head is recorded with a resolution of 0.1°C during engine operation under different working conditions. The test system has high-speed data acquisition and the FBG sensors exhibit better transient performance to dynamic loading than PT100 resistance temperature detector (RTD). Furthermore, we explore the relationship between temperature gradients obtained by the FBG's spectral width as well as the reflected waveform.

English

This paper describes the process of the M337 engine monitoring by the Engine Data Management 800 which is mounted on six aircraft of Air Training and Education Centre. This is the most advanced and accurate piston engine-monitoring system on the market that uses the latest microprocessor technology to monitor critical engine parameters in order to measure parameters as cylinder head temperature and exhaust gas temperature to evaluate each cylinder performance alone. These parameters are monitored during these flight regimes - take off, climb and cruise. Monitoring of the mentioned parameters will help us to increase the economy of the aircraft and also its operation's reliability.

Research on Cylinder Head Thermal State Simulation

The thermal state of the cylinder head has a huge influence on its fatigue and damage situation; therefore it is essential to accurately simulate the thermal state of the cylinder head during engine operation. In this paper, a method research of the cylinder head thermal state simulation test has been done. A thermal state simulation test bench has been launched, using induction heating and water-cooling to regulate the temperature. A series of cylinder head surface temperature field simulation tests has been accomplished. Compared to the actual engine test results, the temperature simulation results have an average error of less than 5% and a maximum error of 8.5% in these temperature test points. It turns out that the test bench can simulate the actual cylinder head temperature distribution accurately and will has significant effects on the research of the cylinder head thermal stress distribution and thermal fatigue situation.