Cylinder Wall Research Articles

Parameter optimization of rubber cylinder of expansion liner hanger based on numerical simulation

The expansion liner hanger has great advantages over the traditional slip liner hanger. Therefore, scholars at home and abroad have carried out extensive research on the expansion liner hanger, but there are few researches on the optimization design of the rubber cylinder of the expansion liner hanger. How to select the size and material of the rubber cylinder is very important to the suspension performance of the expansion liner hanger. Based on the Ø245 mm × Ø178 mm expansion liner hanger as the research object, the condition of the changes under the wall thickness and friction coefficient, using the finite element analysis software of rubber cylinder elongation rate, stress conditions are numerically simulated. The results show that when the wall thickness of the rubber cylinder is t = 1.5 mm, the elongation rate of the rubber cylinder is 2.14 mm, and then the elongation rate of the rubber cylinder increases rapidly with the increase of the wall thickness, and the growth of elongation rate slows down when the wall thickness is t ≥ 3.0 mm. The contact stress of the inner and outer walls of the rubber cylinder increases with the increase of the wall thickness, and the contact stress of the inner wall of the rubber cylinder fluctuates, and the fluctuation tends to be gentle when t ≥ 2.5 mm, and the residual stress of the rubber cylinder is uniformly distributed when t ≥ 2.5 mm. When different friction coefficients (0.05, 0.1, 0.15, 0.2, 0.25, 0.3) were taken between the rubber cylinder and the outer casing, the elongation rate of the rubber cylinder was negatively correlated with the friction coefficient, and the average contact stress on the wall was positively correlated with the friction coefficient. The results of this paper provide guidance for the design and material optimization of the rubber cylinder in the expansion liner hanger.

Dynamic modeling of a free-piston engine based on combustion parameters prediction

A dynamic combustion model (DCM) is proposed for model-based control synthesis design in an opposed-piston free-piston engine (FPE). The DCM combines a modified triple Wiebe function with an artificial neural network (ANN), and considers the effects of engine variables such as cylinder wall temperature, fuel injection quantity and ignition timing. Firstly, it was proved by algebraic analysis that the triple Wiebe function can well describe the three combustion stages of the FPE. The ANN was then trained using the data obtained through CFD simulations at different operating points, with the aim of predicting combustion parameters based on engine variables. After the model was calibrated, it was verified by the test results from a prototype. Furthermore, this model was used to investigate combustion control strategies for cold start and stable operation. The results showed that the DCM has high precision and can simulate the complex combustion process under a wide range of FPE conditions, and is a favorable tool to make control strategies without experiments, especially in the cold start phase. Unlike general combustion modeling methods, this study provides a cost-effective way to build such a model for controller design.

The effect of a high-speed rotational oscillating cylinder on a heated cylinder

This study investigated the effect of a clockwise and counter-clockwise oscillating (control) cylinder on the flow structure and heat transfer on a heated (bare) cylinder placed in the downstream region of the flow experimentally. In this regard, temperature measurements were made regularly for heat transfer analysis. Particle image velocimetry (PIV) technique was used to determine the instantaneous and time averaged flow characteristics such as streamlines (<ψ > ), turbulent kinetic energy (<TKE > ), vorticity contours (<ω > ), the root mean square of streamwise velocity fluctuations < Urms>, and the root mean square of spanwise velocity fluctuations < Vrms >. The effects of oscillating amplitudes and oscillating speed (forcing frequency) on velocity distributions were also analysed at a specified location. The experiments were conducted at the Reynolds number (Re) 5000 based on the diameter of the bare cylinder with two different oscillating amplitudes 8π and 16π and three different forcing frequencies (FR) 3.5, 7 and 14. With the increase of forcing frequencies, it was observed that the wake region became narrower compared to the main cylinder, and then smaller after being moved towards the cylinder wall. In the case of FR = 3.5-16π, the boundary layer separation was found to be prevented by the effect of the oscillating speed and oscillating amplitude, and the dead zone in the rear of the cylinder was completely eliminated. The heat transfer was found to be evenly distributed at almost all points around the cylinder, and to show the best result especially in the rear of the cylinder among all the cases studied. The results obtained from the temperature and PIV experiments were consistent with each other.

Modeling and Fatigue Characteristic Analysis of the Gear Flexspline of a Harmonic Reducer

The failure of harmonic gear drive is mainly caused by the fatigue fracture of flexible wheels and the fatigue damage of flexible bearings. In this paper, the stress sensitivity and fatigue life characteristics of flexible wheels with thin-walled vulnerable components are studied. Firstly, the structure of the flexible wheel of a B3-80 general harmonic gear reducer is designed, the finite element model of the flexible wheel is established by using ANSYS finite element software, and the finite element analysis results are compared with the theoretical calculations to verify the correctness of the model. Finally, by changing the cylinder length, smooth cylinder wall thickness and load, the maximum equivalent stress curves of the flexible gear ring, smooth cylinder and flexible wheel bottom are obtained, and the influence law of structural parameters on the stress characteristics of flexible wheel is obtained. At the same time, the influence laws of flexible wheel cylinder length and smooth cylinder wall thickness on the fatigue life of flexible wheel is studied, which provides a theoretical basis for the structural optimization design of the cup flexible wheel.

Determination of mass transfer coefficient in flow assisted corrosion of steel in liquid Pb[sbnd]Bi. Rotating cylinder geometry

The aim of this experimental and numerical work is to determine the mass transfer at the wall of a steel cylinder rotating within liquid Lead-Bismuth blend. This is a crucial parameter for the analysis of corrosion tests performed in the CICLAD experimental set-up for the investigation of flow assisted corrosion of steel by liquid metals. As a reliable numerical modelling must rely on experimental validation, and since no direct wall mass transfer measurement is possible in CICLAD, a scaled electrochemical model has been achieved. Modelling the turbulence in this rotating configuration is shown to require the use of a Reynolds-Stress Model. A sensitivity to the Schmidt number is observed in the numerical simulations representing the measured mass transfer in the electrochemical model. Simulations dedicated to liquid PbBi are thus presented in addition to those dedicated to the aqueous solution used in the electrochemical model. Following correlations are proposed for the prediction of Fe mass transfer at the wall of a steel rotating cylinder in liquid Pb-Bi:Sh = 1.9 × 10−1(Re2Sc)0.31 for 2 × 109 < Re2Sc < 5.3 × 1010;Sh = 1.4 × 10−3(Re2Sc)0.51 for 5.3 × 1010 < Re2Sc < 8.5 × 1011;Sh = 1.1 × 10−2(Re2Sc)0.43 for 8.5 × 1011 < Re2Sc < 1013.This mass transfer coefficient has recently been used to get a better understanding of corrosion in PbBi [1].

Conjugate Natural Convection: A Study of Optimum Fluid Flow and Heat Transfer in Eccentric Annular Channels

Laminar natural convection-conduction heat transfer in vertically positioned annular channels with inherent eccentricity is investigated for optimum solid-fluid thermal conductivity ratio and optimum cylinder walls thicknesses allowing maximum induced fluid flow rate and heat transfer under varying geometry parameters, i.e., annulus eccentricity and radius ratio. A finite-difference technique is employed to solve the coupled momentum and energy equations for the cylindrical annulus walls and the annular fluid with Prandtl number 0.7. As part of the results, fluctuations in the induced fluid flow rate and heat transfer in the eccentric annular channel due to the conjugate effect, governed by the ratios of the solid and fluid thermal conductivities and thicknesses of outer and inner circular cylinder walls, are obtained for the boundary conditions of one wall heated isothermally and the other kept adiabatic. Commonly encountered ratios of the solid and fluid thermal conductivities and cylinder walls thicknesses are utilized in the present analysis. Results reveal that the optimum conductivity ratio and cylinder walls thicknesses increase nonlinearly with eccentricity and radius ratio. Such results can be very useful in effectively designing the heat transfer equipment for optimum performance.

DEVELOPMENT AND MATERIAL OPTIMIZATION OF 0.67HP PETROL GENERATOR CYLINDER BLOCK USING TAGUCHI DESIGN AND FINITE ELEMENT ANALYSIS

The development of 0.67Hp gasoline generator cylinder block and the material optimization of the component using Taguchi Design and Finite Element Method were carried out successfully. The cylinder block is known to create an avenue for the piston to carry out its reciprocating effect on the crankshaft for onward transmission for the machine output. The designed cylinder block had an engine power of 5.11kw which drove piston through a bore and stroke length of 46.10mm and 51.20mm respectively. The determined clearance volume of 9.46cm 3 was contained in a cylinder wall thickness and block length of 3.04mm and 58.88mm respectively. The designed values were found to be in consonance with recommended values obtained in standard engineering text. The developed mathematical model was determined to be adequate with a statistical Coefficient of determination (R 2 ) of 98.62% and the Adjusted coefficient of determination (Adj R 2 ) was found to be 97.79%. The comparison of optimal values developed from the Taguchi design and genetic algorithm optimizations showed that obtained values from both methods were noticed to be very close as only a difference of about 0.0005 existed among the input parameters. The genetic algorithm result was seen as a kind of validation for the Taguchi design optimization. The Finite element analysis result showed that the temperature output result recorded the highest temperature of 100 o C around the cylinderical bore axis while the lowest temperature of 51.97 o C was found on the cooling fins of the component. Keywords: Optimization, Taguchi Design, Genetic Algorithm and Finite Element Analysis. DOI: 10.7176/JIEA/12-1-04 Publication date: March 31 st 2022

Numerical study on the flow and noise control mechanism of wavy cylinder

Generation of noise caused by the flow around a cylinder and its control are important in various engineering applications. Based on computational fluid dynamics with acoustic analogy and the vortex dynamics theory analysis, this study aims at investigating the ability of the wavy cylinder in improving aerodynamic performance and reducing aerodynamic noise. Noise control mechanisms with different Reynolds numbers are analyzed. The results show that the wavy cylinder is helpful for the reduction of the average drag coefficient and is efficient in suppressing fluctuation of the lift coefficient; consequently, the overall noise of the wavy cylinder is reduced. Specifically, the tonal noise is significantly suppressed or even eliminated under proper configurations. To explore the underlying noise suppression mechanisms, the process of vorticity generation around the wavy cylinder surface is examined in detail. The vorticity distribution on the surface of the wavy cylinder is profoundly improved, and the distribution of the boundary vorticity flux and boundary enstrophy flux is also remarkably weakened. As a result, the generation of vorticity near the wavy cylinder wall is diminished. These directly lead to a significant contraction of the vortex structure distribution in the wavy cylinder wake, especially for some large-scale vortex structures. Moreover, periodic vortex shedding is significantly suppressed in the case with high Reynolds numbers, which might be the main reasons for noise reduction. The interaction area of the positive and negative Lamb vector divergence, which is closely related to the noise generation, is decreased. This contributes to drag reduction and noise attenuation. This indicates that drag reduction and noise suppression are closely bounded in the wavy cylinder.

The Cylinder Liner Temperature Distribution Evaluation of a Diesel Engine Operating with M10, E10, and B10 Fuels

Internal combustion engines are currently so well-optimized that enhancing their performance is a prohibitively expensive endeavor. The success of the engine simulation approach is determined by the accuracy of the heat transfer model. The purpose of these models is to figure out how much heat is transferred from the combustion gases to the cylinder walls. To see which of these relationships may best explain the experimental data for internal combustion engines utilizing various fuel mixtures. The cylinder liner temperature distribution of a diesel engine running on M10, E10, and B10 fuels is presented in this research using the Hohenberg correlation. The results demonstrate that when alcohol is added to mineral diesel fuel, the maximum temperature of the cylinder liner rises by 5.4 percent, 3.7 percent, and 2.23 percent, respectively, allowing the engine to run safely with diesel-alcohol dual fuel.

Effect of split injection on fuel adhesion characteristics under non-evaporation and evaporation conditions

Spray/wall interaction cannot be avoided in direct-injection spark-ignition (DISI) engines. This leads to the formation of fuel adhesions on the piston head and cylinder wall. The fuel adhesion has a negative impact on combustion and emissions. In the present study, the aim is to investigate the effect of split injection on fuel adhesion characteristics under non-evaporation and evaporation conditions. The fuel adhesion of single, double and triple injections was measured using the refractive index matching (RIM) method. Results show that under the non-evaporation condition, split injection decreases the adhered mass ratio from 15.6% to 12.2% at 30 ms after start of injection (ASOI). Two possible reasons can be concluded as “splashing” and “suction” effects. However, under the evaporation condition, split injection increases the adhered mass ratio slightly. The “heat transfer” has the advantage over “splashing” and “suction”. The main reason is that the fuel adhesion of split injection has short time for heat-transfer with the hot wall and high-temperature ambient gas, leading to more adhesion left on the wall. Furthermore, split injection promotes the uniformity of the fuel adhesion on the wall under non-evaporation and evaporation conditions. Finally, these results could provide data for the development of simulation models.

Evaluation of the Detonation Characteristics of Aluminized DNAN‐Based Melt‐Cast Explosive by the Detonation Cylinder Test

AbstractTo investigate the detonation characteristics of a new aluminized DNAN‐based melt‐cast explosive RDA‐2 (containing DNAN (2,4‐dinitroanisole), HMX (cyclotetramethylene tetranitramine) and aluminum), a series of cylinder tests were conducted. The LiF (lithium fluoride) explosive of a similar formulation was also tested to study the influence of aluminum on the detonation characteristics of RDA‐2. The cylinder wall expansion velocities were recorded by Photonic Doppler Velocimetry (PDV). From the experimental data, the detonation velocity, the Gurney energy, the detonation energy, and the CJ pressure of the explosives were calculated. Both the detonation velocity and CJ pressure results indicate that the aluminum seems to have no significant influence on the chemical reaction zone of RDA‐2. The experimental data shows that a large amount of aluminum reacts behind the CJ point. Finally, the parameters of the Jones‐Wilkins‐Lee (JWL) equation of the state of the detonation products were determined.

Experimental investigation on anti-wear coating design for a small aviation kerosene piston engine

The high temperature wear failure of piston-cylinder system is a severe threat to aviation kerosene piston engines. To design a suitable anti-wear coating for the cylinder wall of a small aviation kerosene piston engine, a face contact friction pair and a line contact friction pair were designed to model the friction between the piston and the cylinder wall and the friction between the piston ring and the cylinder wall, respectively, and the graphite coating, the hard anodized coating (HA coating) and the microarc oxidation coating (MAO coating) were prepared on the cylinder wall specimen. Wear tests under high temperature were conducted for both friction pairs, and the friction coefficients, wear mass loss and worn surface morphology were analyzed. The results show that under high temperature condition, the graphite coating shows the least improvement on the wear mass loss and the worn surface state, the MAO coating causes serious wear to the piston specimen of face contact friction pair, while the HA coating is recommended as a suitable anti-wear coating for the engine by effectively reducing the wear mass loss and improving the worn surface state in both line contact and face contact friction pairs.

Perovskite Catalyst for In-Cylinder Coating to Reduce Raw Pollutant Emissions of Internal Combustion Engines.

Aiming to achieve the highest combustion efficiency and less pollutant emission, a catalytic coating for cylinder walls in internal combustion engines was developed and tested under several conditions. The coating consists of a La0.8Sr0.2CoO3 (LSCO) catalyst on an aluminum-based ceramic support. Atomic force microscopy was applied to investigate the surface roughness of the LSCO coating, while in situ diffuse infrared Fourier transform spectroscopy was used to obtain the molecular understanding of adsorption and conversion. In addition, the influence of LSCO-coated substrates on the flame quenching distance was studied in a constant-volume combustion chamber. Investigations conclude that an LSCO coating leads to a reduction of flame quenching at low wall temperatures but a negligible effect at high temperatures. Finally, the influence of LSCO coatings on the in-cylinder wall-near gas composition was investigated using a fast gas sampling methodology with sample durations below 1 ms. Ion molecule reaction mass spectrometry and Fourier transform infrared spectroscopy revealed a significant reduction of hydrocarbons and carbon monoxide when LSCO coating was applied.

Research of the shaft of the new light-load saw cylinder wall

In the article, the task of reducing the mass of the main working body of the gin, i.e. the cylinder shaft by means of the opening of the groove and the design features of the shaft is determined. Its essence is that the inner groove part of the gin saw cylinder shaft performs the circular side with symmetrical gears and the entry of external slits into the grooves in the corresponding inner slits of the shaft leads to a specific equilibrium of the mass relative to the axis of rotation and increases its strength and reliability in operation. This will increase resource efficiency and reliability by significantly reducing the mass of the shaft and saw cylinders without significantly reducing the bending stiffness, as well as obtaining cotton fiber with the required quality characteristics. The issues of creating and defining methods for calculating high-efficiency machine drives and shafts are especially important in the creation of machines for the ginning industry.

Simulation on the effect of compression ratios on the performance of a hydrogen fueled opposed rotary piston engine

Hydrogen internal combustion engines are attracting increasing attention because of no carbon dioxide (CO2) emission and high thermal efficiency for hydrogen combustion. Opposed rotary piston (ORP) engines have simple structures, small size and mass, contributing to the performance improvement of hybrid electric vehicles (HEVs) and range extended electric vehicles (RE-EVs). Compression ratios as an important factor affecting engine performance should be considered in the process of engine designs and optimizations. In this paper, in-cylinder combustion characteristics of a small-scale ORP engine were investigated using a numerical simulation method over different compression ratios (8.90, 9.66, and 10.55). Compression ratio adjustment of the ORP engine may be achieved by the movement patterns of the two shafts. The results indicated that maximum in-cylinder pressure was increased from approximately 3.5 MPa–5.0 MPa when the compression ratios were increased from 8.90 to 10.55. The crank angle (CA) of the maximum in-cylinder pressure was slightly retarded by increasing compression ratios. The hydrogen combustion rates were almost the same before top dead centre (TDC) for the three cases. The combustion durations were dropped from approximately 38.7 °CA to 28.3 °CA when the compression ratios were increased from 8.90 to 10.55; however, the combustion phase of the compression ratio of 9.66 was the earliest among the three cases. The proportions of energy loss by cylinder walls were almost the same under different compression ratios, being approximately 10%; additionally, the indicated thermal efficiency was increased from approximately 34%–39% by changing compression ratios from 8.90 to 10.55. The nitrogen oxides (NOx) emission factors of the ORP engine were almost linearly increased by increasing compression ratios, with the values being higher than 17.2 g/kWh for all the three cases. NOx distributions in combustion chambers around 50 °CA after TDC agreed well with those of in-cylinder temperature and hydrogen residuals.

Study of the Optimum Thermal Insulation Thickness of a Calorimeter Wound with Linen Insulation

In this article, the object of the study is focused on the influence of local insulating materials in the design of a calorific model for the conservation of hot water for a fixed period. The short hollow cylinder is wound with thermal insulation flax between the two walls of the cylindrical device to insulate the interior temperature. The objective of this study is to see the behavior of the thermal resistance of the material as a function of the insulation thickness. The cylinder is modeled by applying the transient analytical method with the heat equation. This analytical resolution of the thermal equation makes it possible to determine the detailed expression of the thermal resistance but also to visualize the evolution curves of this resistance according to the thickness of the insulation under the influence of the contact resistance thermal and heat exchange coefficient on the outside cylinder wall. The results obtained show that the optimum insulation thickness of linen at a temperature of 90 °C is 3.7 cm under the influence of the thermal resistance of the material and 4 cm under the influence of the exchange coefficients thermal.

Variable Speed Diesel Generators: Performance and Characteristic Comparison

Diesel generators (DGs) are set to work as a backup during power outages or support the load in remote areas not connected to the national grid. These DGs are working at a constant speed to produce reliable AC power, while electrical energy demand fluctuates according to instantaneous needs. High electric loads occur only for a few hours a day in remote areas, resulting in oversizing DGs. During a low load operation, DGs face poor fuel efficiency and condensation of fuel residues on the walls of engine cylinders that increase friction and premature wear. One solution to increase combustion efficiency at low electric loads is to reduce diesel engine (DE) speed to its ideal regime according to the mechanical torque required by the electrical generator. Therefore, Variable Speed Diesel Generators (VSDGs) allow the operation of the diesel engine at an optimal speed according to the electrical load but require additional electrical equipment and control to maintain the power output to electrical standards. Variable speed technology has shown a significant reduction of up to 40% fuel consumption, resulting in low GHG emissions and operating costs compared to a conventional diesel generator. This technology also eliminates engine idle time during a low load regime to have a longer engine lifetime. The main objective of this survey paper is to present the state of the art of the VSDG technologies and compare their performance in terms of fuel savings, increased engine lifetime, and reduced greenhouse gases (GHG) emissions. Various concepts and the latest VSDG technologies have been evaluated in this paper based on their performance appraisal and degree of innovation.

Research on Key Factors of Sealing Performance of Combined Sealing Ring

In this study, the mechanical properties of a combined seal ring under different loads were numerically calculated using ANSYS. The effect of the working pressure and pre-compression ratio of a rubber O-ring on the contact stress of the combined seal ring was studied. The influence of the wear ring’s chamfer, thickness, and width on the contact stress and contact force of the combined seal ring was analyzed. Studies have shown that it is particularly important to select a compression ratio that is suitable for the working conditions. Under the same conditions of working pressure and compression ratio, upon increasing the wear ring chamfer, the contact pressure is decreased due to the decreasing contact bandwidth between the wear ring and the cylinder wall. This has little effect on the contact stress of the combined seal ring as well as the contact force, while the width of the wear ring is proportional to the latter.

Effect of double-layer hole nozzle with narrow spray angle on combustion and emissions in dual-fuel natural gas engine

Diesel injection plays a significant role in the mixing process of dual-fuel engine. The diesel nozzle is an important interaction between the injection system and the combustion chamber that deserves more investigation. To fully assess the effect of a diesel nozzle on combustion and emissions in a dual-fuel engine, and to avoid the diesel impingement on the wall and lubricant dilution with early injection strategy, a diesel nozzle with double-layer hole and a narrow spray angle was designed to enhance the air utilization of the central part of the pre-mixture natural gas, matching combustion with an open chamber shape. Comparison of the high dispersion nozzle with a narrow spray angle and a traditional nozzle on combustion was performed in a six-cylinder dual-fuel engine with a low compression ratio. The results showed that the narrow spray angle nozzle is beneficial at low load with earlier pilot injection, but the original nozzle achieves higher thermal efficiency than that of the narrow spray angle nozzle with the same injection strategy in high load conditions. The main cause remains that the narrow spray angle nozzle has a relatively small hole diameter and short spray penetration due to higher charge density at high load. The flame propagation ignited a natural gas mixture near the cylinder wall, resulting in a slower combustion process and a smoother heat release curve. With a relatively moderate combustion process and considerably earlier injection timing, a narrow spray angle nozzle will reduce rough combustion concerns at high load.

A study on underexpanded radial jet impinging on inner wall of cylinder

A jet radially spreading like a disc from a small gap between two circular tubes placed face to face with each other was experimentally analysed in this study. The jet is underexpanded and impinges on a cylindrical inner wall concentric with the circular tubes. Typical cellular structure appears in the jet and a detached shock wave forms near the wall. As this flow pattern is distributed over the circumferential direction, visualization by the shadowgraph method captured them as some ring-shaped shock waves. They indicate the nodes of cell sstructure and a detached shock. The diameter of the shock ring increased as the nozzle pressure ratio increased, and the ring of the node gradually approached that of the detached shock. At a certain nozzle pressure ratio, the detached shock ring jumped in the upstream cell. These shock rings oscillated and amplitude of the oscillation was varied with the pressure ratio. Strain of the wall surface was measured at nozzle pressure ratios ranging from 2.0 to 4.8. The wall surface is deformed by the pressure acting on the wall. The strain histories were analyzed using FFT, and multiple dominant frequencies were observed. These were classified by frequency as high, middle and low bands. The middle-band frequency increased gradually and dropped suddenly at certain nozzle pressure ratios, where the jump of the detached shock occurred. Furthermore, the middle-band frequency was in good agreement with the integer multiple of the dominant frequency in the low band. This means the low-band frequency is the fundamental frequency of the pressure acting on the wall. Therefore, the pressure oscillation on the wall has multiple modes and the mode change synchronizes with the flow pattern change such as the detached shock jump.