Combustion performance investigation of aviation kerosene (RP-3) on a compression ignition diesel engine under various loads

The combustion performance of a compression ignition (CI) four-stroke aviation engine fueled with pure No. 3 rocket propellant (RP-3) was experimentally investigated for comparison with diesel. Pilot injection and main injection for RP-3 and diesel were unified under same test conditions. The results show that when burning RP-3, the maximum power of engine is 1% lower than that of burning diesel, with lower specific fuel consumption (SFC) and effective thermal efficiency (ETE). The combustion durations of RP-3 and diesel show small differences of less than 0.4°CA under heavy loads, while the combustion duration of RP-3 is shorter than that of diesel under low loads. The crank angle at 50% mass fraction burnt (CA50) of RP-3 shows differences of 0.3-1°CA compared to that of diesel. For pilot injection at a high engine speed, the ignition delay angle (IDA) of RP-3 is basically equal to that of diesel. With decreasing engine speed, the maximum difference of 1.2°CA in IDAs exist under medium or small loads. For the main injection, the IDA of RP-3 is lager than diesel under heavy loads at various engine speeds. As the load decreases, the IDA of RP-3 is extended. The peak heat release rate (HRR) of RP-3 during main injection combustion is basically the same as diesel under heavy loads, while the intervention effect of unburnt pilot-injected RP-3 under low loads results in a higher peak HRR.

NEMO project: acoustic detection of vehicle engine speed

As part of the EU Horizon2020 project NEMO, SINTEF has developed an algorithm to detect the engine speed of passing vehicles. Some road vehicles can emit abnormal high noise levels or high levels of exhaust gases in urban conditions. The high noise level can be related to aggressive driving (high acceleration and high engine speed), to a modified or malfunctioning exhaust system, or to other vehicle defects. It is well-known that many motorcycles or mopeds often are equipped with non-original exhaust mufflers, giving high noise levels that can be a nuisance to the community. In the NEMO project, the detecting of so-called high emitters (HE) is essential to reduce the impact of such vehicles on the environment and public health. To enable to categorize HE vehicle based on the driving behaviour, it is necessary to detect both acceleration and corresponding engine speed. The paper describes the principle of the algorithm developed and results from testing on vehicles, including a motorcycle. This test shows that it is feasible to estimate the engine speed, also when the vehicle is accelerating, if the number of cylinders is available for the estimation. Further testing of the algorithm is planned within the NEMO project.

Simulation of Dynamic Stresses on High Performance Engine Valve Spring System Considering Coil Clashing Effect

The valve train plays a major role in the performance of internal combustion engines by controlling the combustion process and it is therefore one of the key aspects for increasing the efficiency of combustion engines. Considering the dynamics, the spring force must be high enough to reliably close the valve preventing from seating bouncing due to surge modes after the valve closure. On the other side, the spring force should be kept as low as possible in order to reduce the engine friction losses and consequently the fuel consumption. In the high-performance engines, the valve springs have to be designed and optimized for sustaining higher stresses with compact dimensions leading to critical material and manufacturing processes. This requires a reduction of moving masses and a strong focus on design and process optimization of the coil springs for reducing the mechanical load and the friction losses at low engine speed. At the same time, valve train should be reliable at high engine speed. The calculation of stresses and contact forces for moving parts under dynamic load is essential for durability analysis. A method to calculate the contact of moving masses is described and proposed to justify valve motions experimental results. To fully understand the failure mechanism of test bed reliability trials, the dynamic stresses have been calculated modeling the real springs’ shape. The contact forces have been reproduced considering the coil clash effects and the dynamic behavior of the flexible spring.

Analisis Kekasaran Baja AISI 304 Akibat Variasi Parameter pada Proses Roughing CNC Turning Menggunakan Pahat Cermet

This study aims to determine the surface roughness value of AISI 304 steel due to variations in spindle speed and feed motion. The method used is pre-experimental design and data analysis techniques used are descriptive analysis techniques. The spindle rotation speed used is 1990 rpm, 2100 rpm, and 2300 rpm, while the feed motion used is 0.18 mm / rev, 0.23 mm / rev, and 0.28 mm / rev. The cutting tool used in this study is a Mitsubishi brand insert chisel with ISO standard CNMNG120404-MA, while the data collection technique using a measuring tool to measure the surface roughness of the workpiece is the Surface Roughness Test Mitutoyo Portable Surftest SJ 301 series. The results of this study indicate that high engine speed reaches 2300 Rpm and low feed motion reaches 0.18 mm / rev resulting in low surface roughness levels reaching 2.17 µm. While the highest is obtained at low engine speed and high feed motion which reaches 1900 Rpm and 0.28 mm / rev with a surface roughness value of 4.43 µm.Keywords: Spindle rotation, feed speed, turning, CNC lathe, surface roughness.

PENGARUH PENINGKATAN TEKANAN TERHADAP UNJUK KERJA ENGINE SATU SILINDER

Ignition timing in an important at internal combustion. Timing has a role to synchronize the system in order to get optimal energy. Ignition time is directly related to working pressure in the combustion chamber. The delay combustion will result in higher work pressure. Increased work pressure can increase the performance of the fuel motor and can reduce emissions because combustion is encouraged to be more perfect. Various methods can be done to accompany the conditions of delay combustion to increase work pressure by increasing the octane number. This research focuses on the influence of the one-step gasoline engine performance variable. Effective octane enhancing solutions are used to increase pressure with the concept of combustion delay. Octane-enhancing solutions can be used in various types or concentration in fuel. The results of the study are that torque can increase up to 15% and the power can increase up to 20% compared to standard testing conditions. This is effective at medium to high engine speed.

Application of a zero-dimensional model to assess the effect of swirl on indicated efficiency

Increasing internal combustion engine efficiency continues being one of the main goals of engine research. To achieve this objective, different engine strategies are being developed continuously. However, the assessment of these techniques is not straightforward due to their influence on various intermediate phenomena inherent to the combustion process, which finally result in indicated efficiency trade-offs. During this work, a new methodology to assess these intermediate imperfections on gross indicated efficiency using a zero-dimensional model is developed. This methodology is applied to a swirl parametric study, where it has been concluded that the heat transfer and the rate of heat release are the single relevant changing phenomena. Results show that heat transfer always increases with swirl affecting negatively gross indicated efficiency (around −0.5%), while the impact of combustion velocity is not monotonous. It is enhanced up to a certain swirl ratio (it changes with engine speed) at low engine speed (resulting in an increment of +1.7% in gross indicated efficiency), but it is slowed down at high engine speed with the consequent worsening of gross indicated efficiency (−0.8%).

CO2 concentration from turbocharged common rail diesel engine dually fueled with compressed biomethane gas controlled at optimum ratio

The objectives of this study are to investigate the carbon dioxide (CO2) concentration from the compressed biomethane gas (CBG) and diesel dual-fueled diesel engine and to compare the CO2 concentration produced from the dual-fueled and the diesel-fueled engines. The duration of CBG injection was controlled by following the optimum ratio of the CBG obtained from the previous study. During the test, the engine speed was varied from 1,000 to 4,000 rpm and the engine torque was maintained to be 25, 50, 75 and 100% of the maximum engine torque. Experiment was divided into two parts consisting of the dual-fueled and the diesel-fueled modes. From the dual-fueled mode, when the engine speed increased, the CO2 concentration decreased. Because the optimum ratio of the CBG and the volumetric efficiency decrease during the high engine speed range, the proportion of the diesel increases, the incomplete combustion occurs. The unburned carbon oxidizes to be the CO in higher proportion than the CO2, thus, the CO2 consequently decreases. From the CO2 comparison, the dual-fuel mode produced the CO2 nearly the same as that of the diesel-fuel mode during the low engine torque. On contrary, the dual-fuel mode had higher CO2 concentration during the high engine torque.

Evaluation of the impact of the hydration degree of bioethanol on the operation parameters of the spark-ignition engine

The article presents an overview of methods for the production of bioethanol and the possibility of its use to power internalcombustion engines. The effects of supplying spark-ignition engine with bioethanol having various degrees of hydration were examined experimentally on the engine dynamometer. The measurement results were referred to the anhydrous bioethanol, which is used widely as petrol biocomponent and compared in terms of the course of the pressure in the combustion chamber of the engine as well as engine performance parameters – torque and power. It was found that with the decrease in alcohol concentration, the performance of the sparkignition engine deteriorated. The reduction of in-cylinder pressure was proportional to the increase in the water content in the fuel. No significant changes in the general shape of in-cylinder pressure curves were observed. Engine torque and power decreased with an increase in the water content in the fuel, especially at high engine speed. It has been stated that supplying the engine with bioethanol containing up to 6% (v/v) of water does not result in significant losses in engine performance.