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In this research, an annular combustion chamber with swirlers is introduced in a micro-gas turbine engine for power production. The impact of the dilution holes position and swirler vane angles on the performance of the combustion chamber is investigated. Furthermore, optimization of the combustion chamber is carried out to accommodate a multi-fuel blend, incorporating pure methane, natural gas, and ethanol. The combustor is designed in SolidWorks, and simulations are performed in Ansys Fluent for two positions of dilution holes in the liner and swirler blade angles. The model used is non-premixed with a compressible k – ε turbulent flow model and an equilibrium probability density function for the chemical reaction. To measure the performance of the combustion chamber, pollutant emissions, combustion efficiency, and outlet temperature are examined. Pollutant emissions such as carbon monoxide and unburned fuels exist in a small amount; however, nitric oxides are negligible. The combustion efficiency found is above 98% for methane and natural gas, and almost 100% for ethanol. Moreover, simulation results reveal that the swirler vane angle of 45° widely improves combustor performance.

Currently, steady-state analysis predominates in combustion chamber design, while dynamic combustion characteristics remain underexplored, and there is a lack of a comprehensive index system to assess dynamic combustion behavior. This study conducts a numerical simulation of the dynamic characteristics of the combustion chamber, employing a method combining large eddy simulation (LES) and Flamelet Generated Manifold (FGM). The inlet air temperature, air flow rate, and fuel flow rate were varied by 1%, 2%, and 3%, respectively, with a pulsation period of 0.008 s. The effects of nine different inlet parameter pulsations on both time-averaged and instantaneous combustion performance were analyzed and compared to benchmark conditions. The results indicate that small pulsations in the inlet parameters have minimal impact on the steady-state time-averaged performance. In the region near the cyclone outlet, which corresponds to the flame root area, pronounced unsteady flame characteristics were observed. Fluctuations in inlet parameters led to an increase in temperature fluctuations near the flame root. Analysis of the outlet temperature results for each operating condition reveals that inlet parameter fluctuations can mitigate the inherent combustion instability of the combustion chamber and reduce temperature fluctuations at the outlet hot spot.

The application of short burn durations at lean engine operation has the potential to increase the efficiency of spark-ignition engines. To achieve short burn durations, spark-assisted compression ignition (SACI) as well as active pre-chamber (PC) combustion systems are suitable technologies. Since a combination of these two combustion concepts has the potential to achieve shorter burn durations than the application of only one of these concepts, the concept of jet-induced compression ignition (JICI) was investigated in this study. With the JICI, the fuel is ignited in the PC, and the combustion products igniting the charge in the main combustion chamber (MC) triggered the autoignition of the MC charge. A conventional gasoline fuel (RON 95 E10) and a Porsche synthetic fuel (POSYN) were investigated to assess the fuel influence on the JICI. Variations of the relative air/fuel ratio in the exhaust gas (λex) were performed to evaluate both the occurrence of the JICI and the dilution capability. To assess the sensitivity of the JICI, variations of the engine speed and the engine load were performed. When using RON 95 E10, a shift from a conventional PC combustion to the JICI was observed between λex = 2.3 and λex = 2.5. The variations of the engine speed and the engine load revealed an increased JICI intensity when the engine speed decreased and when the engine load increased. When using POSYN, no JICI was observed. The occurrence of the JICI was correlated to the knock resistances of the fuels, i.e., the lower knock resistance of RON 95 E10 yielded the JICI, whereas the higher one of POSYN did not. At λex = 2.8, applying POSYN resulted in an increase of the burn duration of 5.5°CA, which was a relative increase of 41%, compared to the use of RON 95 E10 due to the absence of the JICI in case of POSYN. However, the application of POSYN resulted in the highest net indicated efficiency (ηi,net). In particular, the application of RON 95 E10 yielded a maximum of ηi,net = 41.5% at λex = 2.6, whereas using POSYN resulted in a maximum of ηi,net = 42.6% at λex = 2.2 due to the higher knock resistance of POSYN.

This paper deals with the effects of piston bowl geometry (hemispherical bowl, troded bowl, and re-entrant bowl) and fuel injection pressure (200 bar, 220 bar, and 240 bar) with hydrogen-diesel/1-pentanol (B20 (80% diesel and 20% pentanol) + 12 lpm of hydrogen) on the emission, combustion, and performance characteristics of a common rail direct injection diesel engine. Re-entrant bowl outperforms hemispherical and troded bowl in terms of brake thermal efficiency (5.67%) and hydrocarbon (8% reduction) with an increase in the fuel injection pressure (240 bar) at part and full load. However, with the increase in the fuel injection pressure in the re-entrant bowl, a slight reduction in nitrogen oxide emissions (2%) is observed. With an increase in injection pressure in the case of re-entrant bowls, NHRR (net heat release rate), peak pressure (in-cylinder), and ROPR (rate of pressure rises) all rise significantly by 3.4%, 4.2%, and 2.3%. It is found that changing the piston shape and fuel injection pressure simultaneously is a potential alternative for improving engine performance and lowering emissions.

This experimental research seeks to explore how varying injection pressures impact the combustion characteristics of diesel fuel under low-temperature combustion (LTC) conditions. The experiments were carried out in a constant volume combustion chamber (CVCC) system equipped with a high-pressure common rail injection system. The ambient temperature of 800 K represents the LTC condition within the chamber, generated using a pre-combustion technique. The combustion pressure, heat release rate, and ignition delay were derived from the combustion pressure data recorded by a piezoelectric transducer sensor. The combustion characteristics of low-temperature conditions were compared with those of conventional diesel combustion engine conditions (1000 K) at high fuel injection pressures (800 bar and 1200 bar). The results indicated a higher maximum combustion pressure and a peak in the heat release rate under LTC conditions, primarily due to an extended ignition delay, which resulted in a greater accumulation and combustion of fuel during the uncontrolled combustion phase. However, the chemical combustion rate under LTC conditions deteriorates with increased fuel injection pressure, attributed to the longer liquid penetration length and higher latent heat effects of fuel vaporization. Therefore, reducing the injection pressure has significant potential to enhance combustion efficiency and shorten combustion duration, but it would also retard the combustion phase away from the start of injection.

The notable increase in combustion noise in the 7–10 kHz band has become an issue in the development of pre-chamber jet ignition combustion gasoline engines that aim for enhanced thermal efficiency. Combustion noise in such a high-frequency band is often an issue in diesel engine development and is known to be due to resonance in the combustion chamber. However, there are few cases of it becoming a serious issue in gasoline engines, and effective countermeasures have not been established. The authors therefore decided to elucidate the mechanism of high-frequency combustion noise generation specific to this engine, and to investigate effective countermeasures. As the first step, in order to analyze the combustion chamber resonance modes of this engine in detail, calculation analysis using a finite element model and experimental modal analysis using an acoustic excitation speaker were conducted. As a result, it was found that there are two combustion chamber resonance modes in the 7–10 kHz band, both of which affect the high-frequency oscillation of the in-cylinder pressure. Both resonant modes have mode shapes that form a single nodal plane in the diametrical direction including the central axis of the cylinder, but the orientations of those nodal planes differ by 90 degrees. In addition, the two resonance frequencies are influenced by not only the bore diameter, temperature, and heat capacity ratio, but also the spatial shape of the combustion chamber. Therefore, when the piston descends and the spatial shape of the combustion chamber changes, the resonance frequencies change as well.

Gas turbine engines are used in many applications such as power plants and aircrafts. The energy generated through fuel combustion has a significant impact on fluid flow characteristics and thrust force produced by gas turbine engines. This energy generation is based on the precise mixing of fuel and air with known proportions. The present research work attempts to examine the characteristics of fluid flow for aero-engine combustion in a chamber with either a single fuel inlet or multiple fuel inlets using the computational fluid dynamics (CFD) technique. Developed in Creo-6.0 parametric design software, the combustion chamber was modeled and simulated using the ANSYS CFX simulation platform to determine the pressure and other fluid flow-induced characteristics. The analysis was performed for both single fuel inlet and multiple fuel inlet combustion chamber designs. The outlet pressure of the combustion chamber is a key parameter in determining the combustion characteristics and subsequent gas expansion in gas turbine performance. Our results indicated that the outlet pressure from the double fuel inlet design was 49.04% higher than the single fuel inlet design. The thrust force (propulsion) in gas turbine engines is a result of the mass flow rate of exhaust gasses, as quantified by the gas exit velocity. Induced thrust on a combustor with double fuel inlet was 48.3% higher than the induced thrust in the single fuel inlet design, making the double fuel inlet design a more viable option. The higher outlet pressure obtained in the double fuel inlet design showed higher enthalpy generation and greater energy conversion into thrust. The cause of this higher enthalpy is attributed to better fuel combustion in the primary zone. It appears that the double fuel inlet design could improve total turbine efficiency, reduce fuel consumption, and lower emissions.

Monitoring the flue gas temperature is a crucial issue for Waste-to-Energy (WtE) plants companies, since it is essential to preserve the materials in the post-combustion chamber, the energy efficiency of the plants as well as to control the emissions of pollutants. As of today, the temperature of flue gases in such plants is commonly monitored by means of thermocouples, infrared pyrometers or aspirated thermocouples. However, all these instruments show limitations in terms of accuracy and reliability inside post-combustion chambers. In this paper, the authors present the thermo-fluid dynamics design of a novel device aimed at mitigating the issues of existing technologies, realised by using the modern CFD techniques. Numerical analyses, performed with the open-source OpenFOAM code, allowed to find a suitable shape for the device and to give a first estimate of the measuring errors, which are of the order of 2% (∼26 K at the typical working temperature of WtE plants’ post-combustion chambers).

The present work address the CFD analysis for scramjet combustor with diamond-shaped strut injectors at supersonic Mach 4.5 and it's based on species transport combustor which is standard k-epsilon turbulence model. It is implied for supersonic combustion that the ramjet engine is focused for operating high speed engines. The combustion chamber assists as an envelope to clutch the propellant for a satisfactory period to certify complete mixing as well as combustion. The diamond-shaped strut injector gives the maximum temperature and pressure of 3517 K and 1.487 MPa respectively whereas the combustion efficiency is found to be 87.2%. The shear layers losses are extremely minimize the performance of the engine, thus interpreting trade-off programmes in a very difficult way to achieve maximum combustion efficiency. Further firmness by machines is essential for achieving higher combustion efficiency.

A brief overview of the designs of low-emission gas turbine-type combustion chambers is given using the example of aircraft propulsion systems. The most promising technology that helps reduce emissions of harmful substances is the combustion of a lean premixed fuel-air mixture, but its use is limited by nonstationary phenomena that have a significant impact on flame stabilization and lead to the occurrence of thermoacoustic resonance. Currently, this technology is implemented for high-power engines by only two companies: General Electric and Rolls-Royce. Work on creating a high-thrust engine in Russia is being carried out at AO UEC-Aviadvigatel within the framework of the PD-35 program. The problems of developing low-emission combustion chambers for gas pumping units are successfully solved at AO UEC-Aviadvigatel together with the Baranov Central Institute of Aviation Motor Development (GTU-16P). One of the key areas of energy development is also the development of high-power gas turbines of the classes GTE-65, GTE-170 (PAO Power Machines), GTD-110M (ODK Saturn), and here it is necessary to solve the same problems as for gas turbine engines. The most pressing problems are predicting the occurrence of thermoacoustic self-oscillations of gas in combustion chambers and controlling them using feedback both in nominal modes and in low-power modes. A review of technologies using low-emission combustion chambers is presented, and the current state of experimental studies of the flow structure and transfer processes in model combustion chambers is considered. Examples of advanced experimental stands that simulate flow and combustion in gas turbine-type combustion chambers are given and the necessary operating parameters and the technical solutions used are indicated that allow efficient measurements using modern optical diagnostic methods.