Piston Surface Research Articles

Single-ended retroreflection sensors for absorption spectroscopy in high-temperature environments

Novel single-ended sensor arrangements are demonstrated for in situ absorption spectroscopy in combustion and related test articles. A single-ended optical access technique based on back-reflection from a polished test article surface is presented. H2O vapor absorption spectra were measured at 10 kHz in a homogeneous-charge compression-ignition engine using a sensor of this design collecting back-reflection from a polished piston surface. The measured spectra show promise for high-repetition-rate measurements in practical combustion devices. A second sensor was demonstrated based on a modification to this optical access technique. The sensor incorporates a nickel retroreflective surface as back-reflector to reduce sensitivity to beam steering and misalignment. In a propane-fired furnace, H2O vapor absorption spectra were obtained over the range 7315–7550 cm− 1 at atmospheric pressure and temperatures up to 775 K at 20 Hz using an external-cavity diode laser spectrometer. Gas properties of temperature and mole fraction were obtained from this furnace data using a band-shape spectral fitting technique. The temperature accuracy of the band-shape fitting was demonstrated to be ±1.3 K for furnace measurements at atmospheric pressure. These results should extend the range of applications in which absorption spectroscopy sensors are attractive candidates.

“Simultaneous measurement of flame impingement and piston surface temperatures in an optically accessible spark ignition engine”

This paper shows the results of spatially resolved temperature measurements of the piston surface of an optically accessible direct injection spark ignition engine during flame impingement. High-speed thermographic phosphor thermometry (TPT), using Gd3Ga5O12:Cr,Ce, and planar laser-induced fluorescence of the hydroxyl radical (OH-PLIF) were used to investigate the temperature increase and the time and position of flame impingement at the piston surface. Measurements were conducted at two operating cases and showed heating rates of up to 16,000 K/s. The OH-PLIF measurements were used to localize flame impingement and calculate conditioned statistics of the temperature profiles. The TPT coating was characterized and its influence on the temperature measurements evaluated.

Investigation of the effects of tripropylene glycol addition to diesel fuel on combustion and exhaust emissions at an isolated diesel engine

Low emission in diesel engines increases the importance of low fuel consumption and high efficiency. In this experimental study, the parts forming the combustion chamber were coated with ceramic materials, which had low thermal conductivity and resistance to high operating temperature, in order to reduce the loss energy and harmful emissions in a diesel engine. This study was conducted in 3 stages. In the first stage, cylinder liner and the valves were coated by using boronizing method. In the second stage, piston surface was coated by using plasma spray method. In the third stage, tripropylene glycol+diesel mixtures (added as 2%, 4%, and 6% by volume) were used in coated (COE) and uncoated (STE) engines. The results determined that in coated engine, carbon monoxide (CO), hydrocarbon (HC), smoke emissions and brake specific fuel consumption (BSFC) values of diesel fuel and tripropylene glycol+diesel mixtures decreased; whereas, nitrogen oxide (NOx), exhaust gas temperature (EGT) and brake thermal efficiency increased.

Opposed piston linear compressor driven two-stage Stirling Cryocooler for cooling of IR sensors in space application

A two-stage Stirling Cryocooler has been developed and tested for cooling IR sensors in space application. The concept uses an opposed piston linear compressor to drive the two-stage Stirling expander. The configuration used a moving coil linear motor for the compressor as well as for the expander unit. Electrical phase difference of 80 degrees was maintained between the voltage waveforms supplied to the compressor motor and expander motor. The piston and displacer surface were coated with Rulon an anti-friction material to ensure oil less operation of the unit. The present article discusses analysis results, features of the cryocooler and experimental tests conducted on the developed unit. The two-stages of Cryo-cylinder and the expander units were manufactured from a single piece to ensure precise alignment between the two-stages. Flexure bearings were used to suspend the piston and displacer about its mean position. The objective of the work was to develop a two-stage Stirling cryocooler with 2W at 120K and 0.5W at 60K cooling capacity for the two-stages and input power of less than 120W. The Cryocooler achieved a minimum temperature of 40.7K at stage 2.

Friction Reduction Effect Between Piston and Cylinder Surface Treatment Using Floating Liner Engine

Friction Reduction Effect Between Piston and Cylinder Surface Treatment Using Floating Liner Engine

Investigation of the cavitational stability of an aluminum piston surface based on a three-dimensional model

The problem of determining the optimal material for manufacturing the surface of a movable element (piston) is considered, which has an increased resistance to cavitation failure, in order to justify the expediency of using structural materials for the manufacture of pistons in fuel automatics elements. On the basis of three-dimensional numerical modeling of the elasticity equations, the conditions under which a cavitation bubble collapse on the surface of a piston made of various structural materials can lead to irreversible deformations of the piston. The pressure acting on the piston determined from the model of nonspherical bubble collapse with the formation of a cumulative stream. The impact on the surface of the collapse of both a single bubble and a pair of bubbles located at different distances from each other is studied. Calculations showed that with special treatment the surface of the piston will become more resistant to erosion destruction. Deformations are localized near the region to which the force is applied, at a distance of the order of two bubble diameters. Cavitation destruction of the material is associated with the yield threshold and grain size, is independent of the Young's modulus and inversely proportional to the Poisson's ratio. The simultaneous collapse of two bubbles at a distance of the order of one or two sizes of the bubble increases the maximum pressure on the surface and, consequently, increases the probability of irreversible deformation of the surface.

Correlation between Piston Surface Temperature and Piston Material and their Influence on Spray-Wall-Interaction and Spray Combustion

Correlation between Piston Surface Temperature and Piston Material and their Influence on Spray-Wall-Interaction and Spray Combustion

Light source optimization for automatic visual inspection of piston surface defects

This paper focused on the light source optimization for visual inspection of piston surface defects. A novel structured lighting system was developed to overcome the difficulties in the well-qualified imaging of tiny and random defects on the cylindrical smooth surface of components such as pistons. A polarized light-filtering based method was proposed to enhance the defect image contrast, enlarge the detection range, and suppress the noise of flawless area. It was both experimentally proven and theoretically proven effective by mathematical modeling of light intensity loss during light propagation. To analyze the influence of the pose and position of light sources on defect imaging quality, the system model for camera, light source, and workpiece was established, and the structure parameters of the lighting system were optimized to improve the brightness uniformity over the entire inspection region and lighting efficiency. Moreover, a soft lighting method was introduced as a subsidiary means of removing the surface noise at two ends of a piston. This method was found to be more effective compared with conventional software filtering algorithm. Finally, a case was examined. The defects on the automotive brake master piston surface were captured using the optimized light source system. A random sampling experiment with 600 specimens revealed that the false-positive rate was about 2.3%, and with no leak detection. The findings have been applied in the production, and it is expected to be referred in inspecting defects on other smooth cylindrical surfaces.

하수처리장 바이오가스를 이용한 발전시 가스엔진의 고장원인 분석

본 연구에서는 실제 난지 하수처리장에서 바이오가스를 연료로 사용하여 발전할 때, 가스엔진에서 발생하는 고장 사례에 대한 조사와 분석을 통해 바이오가스 플랜트의 주요 고장원인을 분석하고, 그 대책을 제시하였다. 바이오 가스엔진에 유입되는 바이오 가스 속의 황화수소와 수분 제거설비의 간헐적인 오작동으로 인한 수분이 바이오 가스엔진의 인터쿨러 부식을 초래하였다. 또한 바이오가스 속의 실록산이 이산화규소와 규산염 화합물을 형성하여 피스톤 표면 및 실린더라이너 내벽의 긁힘과 마모 등의 손상을 유발하였다. 연소실과 배기가스 설비에 부착된 물질들은 황화수소와 다른 불순물질이 결합한 것으로 분석되었다. 이러한 원인으로는 바이오 가스 속의 고함량(50ppm이상)의 황화수소가 탈황설비에 장기간 공급되었고, 탈황설비내 활성탄의 파과점 도달에 따른 제거효율 저하 때문에 황화수소가 엔진으로 유입됨으로써 발생한 것으로 사료된다. 또한, 황화수소는 흡착탑의 실록산 제거용 활성탄 기능을 저하시킴으로써 제거되지 않은 실록산 화합물이 엔진으로 유입되어 다양한 형태의 엔진고장을 유발한 것으로 판단된다. 따라서, 황화수소와 실록산, 수분은 바이오 가스엔진 고장의 주요 원인으로 볼 수 있으며, 이 중 황화수소는 고장을 일으키는 다른 물질과 반응하며, 전처리 공정에 중대한 영향을 미치는 물질로 볼 수 있다. 결과적으로, <TEX>$H_2S$</TEX> 제거방법의 최적화가 안정적인 바이오 가스엔진 운영을 위한 필수적인 대책으로 사료된다. In this study, we analyzed the causes of major faults in the biogas plant through the case of gas engine failure when cogenerating electricity and heat using biogas as a fuel in the actual sewage treatment plant and suggested countermeasures. Hydrogen sulfide in the biogas entering the biogas engine and water caused by intermittent malfunction of the water removal system caused intercooler corrosion in the biogas engine. In addition, the siloxane in the biogas forms a silicate compound with silicon dioxide, which causes scratches and wear of the piston surface and the inner wall of the cylinder liner. The substances attached to the combustion chamber and the exhaust system were analyzed to be combined with hydrogen sulfide and other impurities. It is believed that hydrogen sulfide was supplied to the desulfurization plant for a long period of time because of the high content of hydrogen sulfide (more than 50ppm) in the biogas and the hydrogen sulfide was introduced into the engine due to the decrease of the removal efficiency due to the breakthrough point of the activated carbon in the desulfurization plant. In addition, the hydrogen sulfide degrades the function of the activated carbon for siloxane removal of the adsorption column, which is considered to be caused by the introduction of unremoved siloxane waste into the engine, resulting in various types of engine failure. Therefore, hydrogen sulfide, siloxane, and water can be regarded as the main causes of the failure of the biogas engine. Among them, hydrogen sulfide reacts with other materials causing failure and can be regarded as a substance having a great influence on the pretreatment process. As a result, optimization of <TEX>$H_2S$</TEX> removal method seems to be an essential measure for stable operation of the biogas engine.

3D Numerical Study of Piston Head Design and Cooling Gallery Position Effects on the Thermal Analysis of a Marine Diesel Engine Piston

The main objective of this study is to investigate the effect of design variables on numerical thermal analysis of a marine diesel engine piston. Two different design variables are considered in this work. The first design variable to be investigated is piston head geometry and the effects of its modification on temperature distribution of a marine diesel engine piston are studied. Three different cases are investigated and the first case is taken for a bowl piston head which is considered the reference case. For second and third cases, a flat piston head and a domed piston head are studied. The numerical thermal analysis is performed for these three cases and the results show that flat top piston is less affected by the combustion with maximum temperature range of 714.86 K-679 K. On the other hand, the results show that domed top piston is exposed to the highest level of temperature ranging from 727.89 K to 690.57 K. The second design variable studied is cooling gallery position and the effect of its axial movement on temperature distribution. Two positions in the axial direction are taken which are obtained by moving the cooling gallery in increment of 3 mm axially towards the piston head in each case. Results of numerical thermal analysis show that the nearer the cooling gallery to the piston head surface, the lesser is the piston surface temperature. It is also observed that temperature range of referenced bowl top piston is decreased from 713.91 K -678.55 K to 708.4 K-673.38 K when oil cooling gallery is moved by increment of 6 mm axially towards piston head

Failure criteria of heat-stressed parts of piston engines and the review of methods for assessment of pistons durability

During designing, calculation and further development of an engine it is necessary to take into account all the values that define its lifetime. In variable modes of tractor diesel engine, the stress level of piston changes over time, which leads to the appearance of cracks on the edge of combustion chamber. It especially applies to the semi-open combustion chambers. The appearance and growth of crack to a critical length often leads to failure of the combustion chamber edge. In this regard, the selection of failure criteria of pistons in operation is an urgent task. The durability assessment should be made on the criteria of the thermal fatigue strength that could be divided into three groups: the deformation criteria, the deformation and kinetic criteria, the energy criteria. Deformation criteria is the most widely used. Taking into account the active loading in conditions of uniaxial tension, the damage accumulation related to the material plastic deformation, or the peak deformation criterion is determined. Along with experimental methods consuming time and money, the other reliability assessment methods based on the numerical calculations, such as finite element method become common use. The fatigue material properties when loading a small number of cycles are determined by the Coffin-Manson equations in the form introduced by J. Morrow for the amplitudes of elastic and plastic deformations, depending on the number of cycles to failure. The analysis of the works of various authors shows that the crack growth process is not fully considered. The lack of theoretical approach to determining the remaining lifetime demands the improvement of calculation method which should take into account the temperature difference on the surface of piston, gas pressure and piston geometric dimensions affecting the stress concentration.

IMPROVING THE RELIABILITY OF THE PISTON OF HIGH-SPEED DIESEL BOOSTED

The problem of a piston reliability ensuring in the high-power diesel engine service and specifically the tear in particular areas of the piston skirt is discussed in the paper. The creep process and stress relaxation simulation for aluminium silicon alloy Al-25 is performed. The alloy creep threshold in a short-time term is ascertained. The material creep area on the piston surface is determined. The approach for tear elimination in the investigated area is suggested.

Dynamics analysis and design methodology of roll-resistant hydraulically interconnected suspensions for tri-axle straight trucks

A new hydraulically interconnected suspension (HIS) system is proposed to enhance the roll dynamics of the tri-axle straight trucks. The impedance of the hydraulic system is derived with impedance transfer matrix method, and integrated to establish the equations of motion of the mechanical and hydraulic coupling system. Based on the obtained equations, the additional mode stiffness/damping of the vehicle body and wheel state forces are explicitly described with the physical parameters of the hydraulic system. The obtained results indicate that the proposed HIS system can be able to independently enhance the mode stiffness/damping, in which the additional bounce/pitch and roll/warp mode stiffness are determined by the difference and summation of the top and the corresponding bottom piston surface area, respectively. The mode damping is caused by the direction and roll damper valves, simultaneously. The later valves alter the mode damping like the accumulators change the mode stiffness. The comparison of dynamic responses between the trucks with the conventional suspension and the HIS system shows that the HIS system can effectively suppress the roll motion of the truck body and favorably reduce the warp mode force for the wheel stations. Finally, the loss coefficients of the damper valves are tuned in terms of dimensionless factors to handle the compromising indices based on the dynamic responses.

A Combined Numerical and Experimental Study of the 3D Tumble Structure and Piston Boundary Layer Development During the Intake Stroke of a Gasoline Engine

Due to its positive effect on flame propagation in the case of a well-defined breakdown, the formation of a large-scale tumble motion is an important goal in engine development. Cycle-to-cycle variations (CCV) in the tumble position and strength however lead to a fluctuating tumble breakdown in space and time and therefore to combustion variations, indicated by CCV of the peak pressure. This work aims at a detailed investigation of the large-scale tumble motion and its interaction with the piston boundary layer during the intake stroke in a state-of-the-art gasoline engine. To allow the validation of the flow near the piston surface obtained by simulation, a new measurement technique called “Flying PIV” is applied. A detailed comparison between experimental and simulation results is carried out as well as an analysis of the obtained flow field. The large-scale tumble motion is investigated based on numerical data of multiple highly resolved intake strokes obtained using scale-resolving simulations. A method to detect the tumble center position within a 3D flow field, as an extension of previously developed 2D and 3D algorithms, is presented and applied. It is then used to investigate the phase-averaged tumble structure, its characteristics in terms of angular velocity and the CCV between the individual intake strokes. Finally, an analysis is presented of the piston boundary layer and how it is influenced by the tumble motion during the final phase of the intake stroke.

Wear performance of bionic strip-shaped mud pump pistons

The service life of mud pump pistons may be extended by imitating the body surface morphology of earthworms. To achieve this solution, bionic strip structures of various sizes are processed on the working surface of a BW-160 mud pump piston. The service lives of standard and bionic pistons are compared under experimental conditions. Results show that the bionic strip structure clearly improves the service life of mud pump pistons. The influence of the width of a bionic piston strip is greater than that of strip spacing. The bionic strip should not be too small or large because size could have negligible or deleterious effects on service life, respectively. The optimal structure parameters of a bionic strip piston when the optimal contact area between the piston and the cylinder liner is 73.5% are a strip width of 3 mm, strip spacing of 3 mm, and strip number of 3. These parameters improve piston service life by 81.5%. Finite element analysis simulations of wear demonstrate that the bionic strip can change the stress state on the working surface of the piston, increase lubricant storage space, improve the wear resistance of the piston, reduce extrusion injuries on the root, and prolong piston service life.

Effects of thermal barrier coating on the performance and combustion characteristics of a diesel engine fueled with biodiesel produced from waste frying cottonseed oil and ultra-low sulfur diesel

ABSTRACTIn this study, the top surfaces of piston and valves of a four-strokes and direct-injection diesel engine have been coated—with no change in the compression ratio—with a 100 μm of NiCrAl lining layer via plasma spray method and this layer has later been coated with main coating material with a mixture of 88% of ZrO2, 4% of MgO and 8% of Al2O3 (400 μm). Then, after the engine-coating process, ultra-low sulfur diesel (ULSD) as base fuels and its blend with used frying cottonseed oil derived biodiesel in proportion of 20%, volumetrically, have been tested in the coated engine and data of combustion and performance characteristics on full load and at different speeds have been noted. The results, which were compared with those obtained by uncoated-engine operation, showed that thermal efficiency increased, and engine noise reduced. Cylinder gas pressure values obtained from the diesel engine which has been coated with thermal barriers have been found to be somewhat higher than those of the uncoated-engine. Also, maximum pressure values measured in both engines and under the same experimental conditions through the use of test fuel have been obtained after TDC. Moreover, heat release rate and heat release have occurred earlier in the coated-engine. NOx emissions were increased while CO and HC emissions were remained almost the same with a little bit decrease.

Numerical simulation of compressible fluid flow in an ultrasonic suction pump

Characteristics of an ultrasonic suction pump that uses a vibrating piston surface and a pipe are numerically simulated and compared with experimental results. Fluid analysis based on the finite-difference time-domain (FDTD) routine is performed, where the nonlinear term and the moving fluid–surface boundary condition are considered. As a result, the suction mechanism of the pump is found to be similar to that of a check valve, where the gap is open during the inflow phase, and it is nearly closed during the outflow phase. The effects of Reynolds number, vibration amplitude and gap thickness on the pump performance are analyzed. The calculated result is in good agreement with the previously measured results.

Adaptive control in high-speed electric drives of a lathe feed for noncircular turning

Problems of upgrading high-speed electric drives of a lathe feed for machining such bulk and precise products of engineering industry as internal combustion engine pistons with a complex ovate-barrel-like shape are considered. It is shown that these electric drives must have astaticism with respect to chip loading to decrease shape errors. When machining the piston surface, there are both uninterrupted cutting zones and cutting zones with an interruption on part of the spindle revolution as well (for example, when passing bores by a cutter etc.). It is shown that, at the same time, it is reasonable to have the structure with an integrally proportional controller and in the case of cutting interruption with a proportional controller. A controller is proposed with the structure changed as a function of the cutting feature. Application of the adaptive controller with the variable structure in the control system of lathe feed drives for noncircular turning decreases the shape error caused by uninterrupted cutting by 5–20 times in comparison with the linear integrally proportional controller. The additional effect of the application of the adaptive control is attained due to a significant (by several times) increase in the useful life of an expensive diamond cutting tool. The control of the controller structure is effective both in systems with the software formation of controlling actions and in systems using self-training principles.

Effect of coolant temperature on air–fuel mixture formation and combustion in an optical direct injection spark ignition engine fueled with gasoline and butanol

Diversification of the energy mix and the drive for increasing security of supply have extended the use of alternative fuels in internal combustion engines. Butanol is a viable energy source for spark ignition (SI) power units featuring higher energy density and compatibility with existing systems. The present work investigated the use of n-butanol in an optically accessible wall guided direct injection SI engine, operated at low load, as well as wide open throttle. Engine speed and injection pressure were kept constant, while coolant temperature was alternated between two values, so as to simulate cold-start and fully warmed-up conditions. In-cylinder pressure and exhaust gas emission measurements were coupled with optical results obtained through UV–visible flame visualization and 2D chemiluminescence. This allowed a more detailed insight into the occurrence of diffusive flames near the piston surface and an analysis of flame front propagation, as well as its morphology. The correlation of thermodynamic data and flame imaging with band-pass filters for recording the spatial distribution of the OH radical, soot precursors and carbonaceous structures gave information on the evolution of chemical species during combustion. While at low load the alcohol performed slightly better compared to gasoline, at wide open throttle the opposite was recorded. The effect of coolant temperature was more evident for butanol. These observations were correlated to the presence of liquid fuel film on the piston crown, which resulted in slower flame propagation and higher related emissions for the alcohol.

Hydrodynamic growth and decay of planar shock waves

A model for the hydrodynamic attenuation (growth and decay) of planar shocks is presented. The model is based on the approximate integration of the fluid conservation equations, and it does not require the heuristic assumptions used in some previous works. A key issue of the model is that the boundary condition on the piston surface is given by the retarded pressure, which takes into account the transit time of the sound waves between the piston and any position at the bulk of the shocked fluid. The model yields the shock pressure evolution for any given pressure pulse on the piston, as well as the evolution of the trajectories, velocities, and accelerations on the shock and piston surfaces. An asymptotic analytical solution is also found for the decay of the shock wave.