Piston Engine Research Articles

Investigation on the oscillation characteristics and performance prediction of a linear range extender: An analytical and numerical combined method

Linear range extender (LRE) system is directly coupled with free piston engine and linear motor and has great application potential in extended-range electric vehicles. In this paper, an analytical and numerical combined method was adopted to investigate the effect of key design parameters on the design and performance prediction of an LRE system. The results showed that the energy input and consumption reach a balance state, the LRE system maintains a stable steady vibration. Increasing the system load will reduce the piston operating stroke. The peak operating velocity of the piston, the average operating velocity of the piston gradually decrease, the operating frequency and the output power decreases as the load increases. When S/B is 0.8, the system output power reaches 4.5 kW, and when S/B is 1.2, the output power is only 2.2 kW. When the mover mass is 3.0 kg, the system output power reaches 3.8 kW, and when the mover mass is 8.0 kg, the output power is only 2.4 kW. When the excess air ratio increases from 0.8 to 1.2, the peak piston speed was reduced from 6.79 m/s to 6.03 m/s, the average piston operating speed was reduced from 5.30 m/s to 4.96 m/s, and the system operating frequency was reduced from 51.2 Hz to 47.96 Hz. If the LRE system wants to have stronger resistance to load fluctuations, it should choose a larger S/B ratio and a relatively larger mover mass during design. In order to pursue higher power output, the S/B and mover mass must be relatively small.

Experimental study on ammonia-diesel co-combustion in a dual-fuel compression ignition engine

Ammonia, as a carbon-free renewable fuel and a potential hydrogen carrier, is gaining increasing interest in addressing greenhouse gas emissions in industrial applications and transportation. This paper presents experimental studies on the co-combustion of ammonia with diesel fuel in a single-cylinder industrial compression ignition engine operating in dual-fuel mode. The energy share of ammonia ranged from 0 to 60%. Increasing the proportion of ammonia compared to diesel fuel in the compression ignition engine leads to a change in the combustion process character, increasing the kinetic combustion phase at the expense of diffusive combustion. However, it does not result in an increase in the peak pressure rise (PPR) beyond the permissible value of 1 MPa/deg for piston engines. It increases ignition delay and shortens the combustion duration, while also increasing thermal efficiency and decreasing specific energy consumption. An increase in the NH3 share results in a decrease in combustion efficiency, a reduction in unit emissions of NO, CO2, and soot, and an increase in CO emissions. Beyond 42% ammonia share, it reduces unit THC emissions. At a 42% ammonia share, the dual-fuel engine achieves the highest indicated thermal efficiency (ITE), lowest specific energy consumption (SEC), shortest combustion duration, and lowest unit soot emissions.

The Possibility of Powering a Light Aircraft by Releasing the Energy Stored in Hydrogen within a Fuel Cell Stack

In this work, we examine the possibility of converting a light propeller-driven aircraft, powered by a spark-ignition, reciprocating piston, and internal combustion engine running on AVGAS, into one powered by an electric motor driven by a proton exchange membrane fuel cell stack running on hydrogen. Our studies suggest that storing hydrogen cryogenically is a better option than storing hydrogen under pressure. In comparison to cryogenic tanks, high-pressure tanks are extremely heavy and unacceptable for light aircraft. We show that the modified aircraft (including batteries) is no heavier than the original, and that the layout of the major components results in lower movement of the aircraft center-of-gravity as the aircraft consumes hydrogen. However, we acknowledge that our fuel cell aircraft cannot store the same amount of energy as the original running on AVGAS. Therefore, despite the fact that the fuel cell stack is markedly more efficient than an internal combustion engine, there is a reduction in the range of the fuel cell aircraft. One of our most important findings is that the quantity of energy that we need to dissipate to the surroundings via heat transfer is significantly greater from a fuel cell stack than from an internal combustion engine. This is particularly the case when we attempt to run the fuel cell stack at high current densities. To control this problem, our strategy during the cruise phase is to run the fuel cell stack at its maximum efficiency, where the current density is low. We size the fuel cell stack to produce at least enough power for cruise, and when we require excess power, we add the energy stored in batteries to make up the difference.

Heat and mass transfer mechanistic investigation of wall intervention on spray ignition characteristics under aviation piston engine-like conditions

The interaction between spray and walls significantly influences the mixture formation and ignition characteristics in aviation piston engines, primarily due to the dynamics of heat and mass transfer. To elucidate the wall’s influence on the impingement spray ignition process and reconcile discrepancies in the extant literature, we conducted a comprehensive suite of optical experiments encompassing free and impinging sprays with wide ambient temperature conditions (680 to 1200 K). Numerical simulations were utilized to dissect the flow field’s distribution patterns, as well as heat and mass transfer dynamics. Our investigation reveals that impinging sprays exhibit markedly shorter ignition delay times than free sprays under comparable conditions, with this divergence becoming more pronounced at lower ambient temperatures. Notably, impingement sprays are capable of auto-ignition at reduced ambient temperatures. The spray-wall interaction effect accelerates the accumulation of heat from the low-temperature reaction, facilitating swifter attainment of the threshold temperature for the high-temperature reaction. This is attributable to the generation of a higher quantity of high-temperature mixtures with a diminished local equivalence ratio. The disparity in the ignition delay times between impinging and free sprays is exacerbated by the elevated heat demand for the transition from low-temperature reaction to high-temperature reaction at lower ambient temperature conditions, predominantly driven by the exothermic nature of low-temperature reaction.

The Hybrid Concept of Turboshaft Engine Enhanced by Steam Cycle Using Waste Heat Recovery—Combined Analytical and Numerical Calculation of Its Efficiency

<div>The article presents a hybrid concept of a turboshaft engine that fits into the area of PGE (pressure-gained combustion). It combines the advantages and elements of a piston engine and a turbine engine. The combustion takes place in isochoric chambers. The proposed timing system of the engine efficiently realizes the Humphrey cycle. Additionally, the main gas cycle engine was enhanced by the Clausius–Rankine steam cycle to achieve effective power of engine equal to 1231.3 kW. It was supplied by waste heat recovery from the exhaust gas. The enhancement of the engine by the secondary steam cycle significantly improved engine effective efficiency with a final value reaching 0.446. The effective efficiency and specific fuel consumption of the engine were calculated using merged analytical–numerical CFD (computational fluid dynamics) analysis. The centrifugal compressor, gas turbine, and steam turbine can work on the common shaft whose rotational velocity is 35,000 rpm. Because of additional weight, it could have potential applications for stationary use or heavy military units.</div>

Computational study of gas-dynamic approach for noise reduction in atwo-stroke engine’s exhaust system

BACKGROUND: The traditional approach to designing exhaust mufflers relies heavily on energy dissipation. In the "gas-dynamic" approach, the flow of exhaust gases is equalized by introducing long channel(s) into the muffler to separate impulses and shift them in time. It is assumed that such mufflers will provide noise reduction without creating significant backpressure. AIMS: To evaluate the potential of the "gas-dynamic" approach to reducing the noise level of two-stroke internal combustion engines. MATERIALS AND METHODS: The study was carried out using computational models. The processes in the gas-air tract of the piston engine were calculated using a one-dimensional (1D) model. The noise characteristic was the effective sound pressure at a specified point in the environment, calculated using 2D model of propagation of disturbances in elastic medium. The object of study was a two-stroke gasoline two-cylinder engine RMZ-551i, with a resonator (providing gas-dynamic supercharging) and a muffler. Initially, the parameters and sound pressure level of the engine with the stock muffler at full load and close to nominal engine speed were calculated. Then, the structure of the stock muffler was modified by adding a "tuned" channel between its two chambers. The parameters of the modified muffler were optimized based on the criterion of reducing gas pulsations at the outlet to the atmosphere. The noise reduction of the muffler implementing the gas-dynamic approach was evaluated relative to the stock muffler and expressed in terms of sound pressure levels in dB. Performance and levels of sound pressure were finally calculated over a wide range of engine speeds. RESULTS: According to the computational estimate, the optimal implementation of the gas-dynamic approach in the muffler reduces exhaust noise by 7 dB, while engine power decreases by 2.5%. Calculation of the sound pressure level based on the external speed characteristic showed that at an engine speed of 3000 rpm, the calculated sound pressure exceedsby 8 dB the minimum (99 dB) obtained for the optimally "tuned" muffler at an engine speed of 5000 rpm. It is suggested that the gas-dynamic approach with optimization is also applicable for uniform noise reduction over a wide range of engine speeds, with a more complex structure of the exhaustmuffler. CONCLUSIONS: Theoretical evaluation of a muffler with a tuned channel connecting its two chambers was carried out, with a two-stroke engine RMZ-551i with a stock muffler as a basis for comparison. At the optimum point on the speed characteristic, the exhaust noise was reduced by 7 dB, while the calculated power decrease was insignificant. The authorsnote the suitability of the methodology for rapid assessments and automated computational optimization of mufflers that utilize wave effects. They also point out the limitations of the models used, which require validation or rather calibration based on experimental data, and the need for the development of applied models of acoustic effects and measuring devices for domestic CAE packages.

Vehicles of Transportation Internal Combustion Engine Press the Details of the Institution Inspection

In this article, the engine in the operation of vehicles details, including cylinder-piston group details, and changes in engine performance, piston rod and cylinders in the details of the cylinder when the body presses the flame-touch surface of the cylinder head redistribution of heat flow occurs, their temperature and the change of grooves in the piston-sleeve connection was analyzed. The study aims to improve the reliable performance of internal combustion engine vehicles by focusing on the maintenance and condition of the cylinder-piston group. The research includes a literature review and experimental analysis of the effects of dust and contaminants on the engine's internal components. Comparative tests were conducted on engines before and after cleaning the cylinder-piston group. Findings show that dust particles significantly impact engine performance, causing a 4-6% reduction in power and a 3-4% increase in fuel consumption. Cleaning the cylinder-piston group resulted in a 5.2% increase in engine power and a 4.0% decrease in fuel consumption. The progressive accumulation of soot was found to degrade engine efficiency and cause knocking. Regular maintenance and cleaning of the cylinder-piston group are essential to enhance engine efficiency and longevity. Implementing these practices in vehicle maintenance systems can significantly improve engine performance and reliability.

Thermomechanical performance and durability analysis of graded thermal barrier coatings over engine piston using finite element analysis

Thermomechanical performance and durability analysis of graded thermal barrier coatings over engine piston using finite element analysis

Improving of the Balancing Structures of In-Line Two-Cylinder Piston Engines

Improving of the Balancing Structures of In-Line Two-Cylinder Piston Engines

Performance evaluation of low heat loss piston engine fuelled with acetylene and cottonseed biodiesel

Performance evaluation of low heat loss piston engine fuelled with acetylene and cottonseed biodiesel

Effect of over-expansion in a cycloidal rotary engine

An over-expanded (Atkinson cycle) reciprocating internal combustion engine is a crucial component of hybrid and range-extended electric vehicles. The realization of the over-expansion cycle with high efficiency in novel power devices with a compact, simple design, such as cycloidal rotary engines, is a promising alternative. The cycloidal rotary engine is an internal combustion engine that operates four strokes without a reciprocating mechanism and valve train. The over-expansion cycle is implemented in the cycloidal rotary engine by asymmetrical intake and exhaust port arrangements, resulting in open and closure timings. This study aimed to establish inherent characteristics of the over-expansion cycle in gasoline-fueled rotary engines with spark ignition. A numerical simulation of the gas exchange and combustion process in a wide range of over-expansion ratios was conducted. It was concluded that the over-expansion cycle is realized without typical piston engine methods such as variable valve timing and multilink mechanism. The thermal conversion efficiency is a peak function of the over-expansion ratio. In the over-expansion range of 1.1–1.2, the thermal conversion efficiency of the cycloidal rotary engine increased up to 32.7–34.5%. The benefits of fuel economy and carbon oxide emission can also be achieved within the specified range of over-expansion ratio.

Assessing the impact of sargassum algae biodiesel blends on energy conversion in a modified single-cylinder diesel engine with a silica-incorporated diamond-like coated piston

ABSTRACT As coal and oil reserves deplete, the world is shifting to alternative fuels and renewable energy. Researchers are exploring a cleaner alternative to fossil fuels for powering automobiles. In this investigation, biodiesel was synthesized from brown marine algae (Sargassum algae) using transesterification process. Silica-incorporated diamond-like coating (DLC) was done on the engine piston by using the chemical vapor deposition (CVD) process with flow rate of 7sccm of C2H2. Three different coating thicknesses, such as 50,100, and 150 µm, were employed on the CI engine piston. Mechanical properties such as hardness, wear, and microstructure analysis were investigated. Analysis of mechanical characteristics reveals that pistons with a 100 μm coating have enhanced characteristics compared to those with other pistons. Using a 100 μm silicon coated piston on a single-cylinder Kirloskar engine, four blends (B10, B20, B30, and B40) were compared to neat diesel. At maximum engine load conditions, the B40 blends produced 42 ppm of HC whereas neat diesel with 19 ppm which is 57% higher than diesel and CO emission concentration increased by 4.9% than diesel. Similarly, brake-specific fuel consumption was observed at maximum load conditions for diesel with 0.18 kg/kWh and 0.20 kg/kWh for B10D90 which is 9.54% higher than diesel. As a result, it is critical to recognize the importance of sargassum’s potential for producing sustainable energy toward green globalization.

Cyclic coupling and working characteristics analysis of a novel combined cycle engine concept for aviation applications

The imperative for small aviation engines lies in the pursuit of heightened power-to-weight ratios and thermal efficiencies. Relying solely on piston engines and gas turbines is insufficient to concurrently meet these evolving performance demands. This paper introduces the concept of a combined cycle aviation engine (CCAE), amalgamating the cycle modes of piston engines and gas turbines. The CCAE achieves flexible control over turbine operating states and engine performance through the adjustment of the energy distribution between these two cycles. The air diversion strategy (α) and the burner's fuel supply strategy (λb) are identified as the key determinants of system performance. To comprehensively investigate the impact of α and λb on CCAE's performance, this paper constructs a theoretical model, a simulation model, and a test bench. The simulation model's accuracy is validated through test data, and the air-fuel ratio range for burner stable combustion is explored. The simulation results indicate a reduction of 50 % in the fluctuation of turbine speed within a single cycle. Under high-altitude conditions, CCAE's intake mass flow rate, power, and efficiency are notably enhanced when compared to conventional turbocharged piston engines. These findings contribute valuable insights that can inform the application of CCAE within the aviation domain.

COMPREHENSIVE REVIEW OF INNOVATION IN PISTON ENGINE AND LOW TEMPERATURE COMBUSTION TECHNOLOGIES

Global transport today is mainly powered by the Internal Combustion Engine (ICE) and throughout its century and a half of development it has become considerably more efficient and cleaner. Future prospects of the ICE rely on the scientific work conducted today to keep this trend of higher efficiency and cleaner emissions in new engines going. The aim of this article is to give a comprehensive review of development directions in novel piston engine designs, which seek to overcome the drawbacks of the ubiquitous 4-stroke piston engine. One of the directions of development is devoted to improving the mechanisms and the general layout of the piston engine to reduce losses within the engine. Research teams working with alternative engine work cycles like the 5- and 6-stroke engine and technologies for extracting waste heat seek to reduce thermal losses while novel layouts of valve trains and crank assemblies claim to significantly improve the mechanical and Volumetric Efficiency (VE) of piston engines. These novel ideas include camless or Variable Valve Action (VVA) and engines with Variable Compression Ratio (VCR) or opposed pistons. One alternative approach could also be to totally redesign the reciprocating mechanism by replacing the piston with some other device or mechanism. Additional scientific work is investigating Low Temperature Combustion (LTC) technologies such as Turbulent Jet Ignition (TJI) and Homogeneous Charge Compression Ignition (HCCI) and its derivatives like Premixed Charge Compression Ignition (PCCI) and Reactivity Controlled Compression Ignition (RCCI) that have shown improvements in thermal and fuel conversion efficiency while also significantly reducing harmful emissions. These combustion strategies also open the path to alternative fuels. The contemporary work in the combustion engine fields of research entail technical solutions from the past that have received a modern approach or are a completely novel idea. Nonetheless, all research teams work with the common goal to make the piston engine a highly efficient and environmentally friendly device that will continue to power our transport and industry for years to come. For this, solutions must be found to overcome the mechanical limitations of the traditional layout of the piston engine. Similarly various improvements in combustion technology are needed that implement state of the art technology to improve combustion characteristics and reduce harmful emissions.

RETRACTED: Research on the kinetics characteristics and in-cylinder combustion of opposed rotary piston engine for different power output modes

As a new type of internal combustion engine, opposed rotary piston (ORP) engine has the advantages of simple structure and high working frequency, and can achieve high power density. Consequently, it stands as an ideal power source for hybrid power systems and unmanned aerial vehicles. The ORP engine has different power output modes, corresponding to different piston rotation and volume evolutions of combustion chamber. However, the effect of power output modes on kinetics characteristics and in-cylinder combustion of ORP engines are still uncovered. In this paper, the kinematic model of an ORP engine is established for scenarios involving power output by different shafts (Shaft 1 and Shaft 3). Meanwhile, the piston rotation patterns and cylinder volume variations are investigated correspondingly. Further, three-dimensional numerical model of the ORP engine is established, enabling analysis of in-cylinder combustion characteristics, engine performance, as well as nitrogen oxides (NOx) emissions. The results indicate that the volume variations of all cylinders follow a consistent pattern under the power output by Shaft 3. A pair of opposed cylinders features longer durations of intake and expansion strokes, and shorter durations of compression and exhaust strokes, the other pair of combustion chambers is the opposite under the power output by Shaft 1. The engine demonstrates a charging efficiency of 95.36 %, with corresponding indicated thermal efficiency and indicated power output of 38.08 % and 40.9 kW, respectively. The two adjacent cylinders present significantly different operation processes in the case of the power output by Shaft 1, achieving charging efficiencies of 94.29 % and 89.11 %, respectively, with the indicated thermal efficiency of 34.49 % and 31.60 %. The corresponding minimum indicated specific fuel consumption under the two power output modes are 211.7 g/kW∙h and 243.7 g/kW∙h, respectively, accompanied by NOx emission factors of 25.3 g/kW∙h and 17.6 g/kW∙h. With the given range of ignition timing, a trade-off relationship exists between the engine performance and NOx emissions. The power density of the case of power output by Shaft 3 is superior to that of Shaft 1.

Combustion characteristics of RP-3 aviation kerosene/n-butanol blended fuel in a compression ignition engine

In order to meet the requirements of Sustainable Aviation Fuel (SAF) to achieve the imperatives of energy conservation and emission reduction. This paper compares the combustion characteristics of diesel, RP-3/n-butanol blends in terms of heat release rate, in-cylinder pressure, temperature and fuel economy in a compression ignition engine, taking into account the advantages of lightweight structure, low fuel consumption and wide range of applications of aviation piston engines. The results certified the viability of applying RP-3 and RP-3/n-butanol blends in diesel engines. Adding n-butanol prolonged the ignition delay and shorten the combustion duration. Moreover, the peak of the pressure, temperature and apparent heat release rate (AHRR) increased. In addition, the blended fuel showed obvious diffusion combustion characteristics at high load. With the n-butanol increased, the combustion instability of the blended fuels decreased significantly, at low load. At n = 2400r/min, pme = 0.53 MPa, compared with diesel, the maximum heat release rate (MHRR) of R70B30 increased by 76.6 %, improving the combustion characteristics of the blended fuel. Moreover, the equivalent specific fuel consumption (ESFC) of RP-3 is 5.56–14.83 % lower than that of diesel, and the effective thermal efficiency (ETE) of RP-3 is 2.8–13.46 % higher than that of diesel under most working conditions.

Research on lightweight design method of diesel engine steel piston based on heat transfer characteristics

Steel pistons are gradually replacing traditional aluminum–silicon alloy pistons as the preferred choice for high-power density engines. However, there is still a lack of systematic research on the heat transfer characteristics of steel pistons in the field of small bore diesel engines. For this reason, this paper was based on the storage temperature testing system to study the variation of temperature field and thermal stress in steel pistons of the small-bore diesel engine under the maximum torque conditions. The results show that there are significant temperature variations in the circumferential path of the steel piston head, indicating that the temperature distribution of the steel piston is highly uneven. The highest temperatures and maximum thermal stresses were found in the rim. To further achieve the lightweighting of the steel piston, a lightweight design method based on heat transfer characteristics was proposed. A multi-objective optimization algorithm was used to optimize the top land height and the position and shape of the cooling gallery. The structural design solutions with volume and thermal stress control were finally obtained. The optimized design solution can reduce the mass by a maximum of 10.01 %, the maximum temperature by a maximum of 35.04 °C and the maximum thermal stress by a maximum of 18.38 % compared to the original design.

Simulation on stirling reverse osmosis desalination power system

In this article, a new power system based on the Stirling engine and hydraulic free piston engine is proposed to provide power for reverse osmosis (RO) desalination. First, the design of the Stirling free piston RO desalination power system was carried out, and the size parameters of the main structures such as the regenerator, heater, cooler, power piston, and valve distribution piston were obtained. A physical model was established to simulate the process of the Stirling engine driving the RO desalination power system based on finite element CFD. The flow field distribution cloud map and output power of the Stirling engine were analyzed. The results indicate that the gas motion of the Stirling engine is stable, and the entire power system can operate normally.

FEM Analysis And Design Optimization Of The Piston

The workings of an engine rely on the piston rod and/or connecting rod to transmit the force of the expanding gas in the cylinder to the crankshaft. Because of its critical role in engines, the piston is subject to inertial stresses and cyclic gas pressure, which may lead to fatigue damage in the form of side wear, fractures in the piston head or crown, and other issues. According to the research, the top of the piston experiences the highest level of stress, which is a major contributor to fatigue failure. This study uses finite element analysis to illustrate the stress distribution on an internal combustion engine's piston. It is the CAD and CAE programs that carry out the FEA. Examining and analyzing the distribution of thermal and mechanical stresses on the piston under real-world engine conditions during combustion is the primary focus. Predicting the component's critical area and greater stress using finite element analysis is also detailed in the paper. Created a structural model of a piston using CATIA software. We ran simulations and stress analyses with the help of ANSYS V14.5.

Determining the influence of synthesis gas additives on the environmental performance of internal combustion engine

The object of research is the environmental parameters of a reciprocating engine when using a synthesis gas additive to the main fuel. The research is aimed at solving the problem of reducing the concentration of harmful components in the exhaust gases of an internal combustion engine by adding synthesis gas to the main fuel. Experimentally, the dependences of the effect of the addition of synthesis gas to ethanol on the change in the environmental performance of a piston engine with spark ignition were obtained. The positive effect of the addition of synthesis gas obtained by thermochemical conversion to ethanol in an amount of up to 5 % by weight on the environmental performance of a spark-ignition piston engine was established. Provided that the engine achieves the same effective power, the use of a synthesis gas additive to the main fuel made it possible to reduce the concentration of CO by 61.5 % and CH by 51.3 % in the exhaust gases. no more than 25–30 words The addition of synthesis gas contributed to the formation of radicals that activate oxidation chain reactions, and also made it possible to increase the normal combustion rate of the fuel-air mixture by 6.25 %. This ensures normal engine operation on a leaner fuel-air mixture (α=1.21) without deterioration of environmental, energy and economic performance. no more than 25-30 words The simultaneous reduction of the concentration of harmful components in the exhaust gases and engine efficiency can be achieved by using fuels with a wide concentration limit of ignition and high combustion rate in a lean mixture. The experimental data obtained can be used in the design or modernization of transport and stationary power plants with internal combustion engines as an approach to meet ever-increasing environmental standards