Throttle Conditions Research Articles

Analysis of spray variations and macroscopic spray characteristics in a gasoline direct-injection engine at different injection timings

Fuel injection timing for early injection mode at higher loads in a gasoline direct-injection engine is critical for mixture formation, combustion process and emissions. In the present work, the effect of fuel injection timing on cycle-to-cycle spray variations and macroscopic spray characteristics is quantitatively analyzed at wide-open throttle condition with stoichiometric air–fuel ratio. A Mie scattering technique was employed to visualize the liquid phase of the fuel dispersion with early injection timings at 180° before top dead center (BTDC), 210° BTDC and 240° BTDC of compression with fuel pressure of 5 MPa. A quantitative analysis using proper orthogonal decomposition revealed that cycle-to-cycle spray variations were not significant. Comparing different injection timings, results, however, showed that spray variations were slightly higher at injection timing of 240° BTDC compared to injection timings at 210° BTDC and 180° BTDC. Concerning macroscopic characteristics, it was found that the spray tip penetration length was longer at 210° BTDC compared to injection timings at 240° BTDC and 180° BTDC. It was also observed that the spray areas were comparable for different injection timings until about 0.9 ms after the start of injection, but it was enhanced at later time stamps for injection at 240° BTDC compared to injections at 210° BTDC and 180° BTDC.

Investigations on combustion characteristics of lean burn SI engine fuelled with Ethanol and LPG

This paper presents an effective experimental approach that can be applied to stationary single cylinder LPG fuelled lean burn SI engine. This approach has been applied to operate the engine under different equivalence ratio at wide open throttle condition. Experiments were conducted at a constant speed of 1500 rpm and at compression ratio of 10.5:1. In this study the effects of adding small amount of ethanol (5%, 10% and 20%) along with LPG were investigated. Ethanol on volume basis was injected along with carburetted LPG. A maximum brake thermal efficiency of 28.5% with 10% ethanol addition for LPG were observed at an equivalence ratio of 0.7. The ethanol addition with LPG extended the lean limit as compared to pure LPG. Also, it was observed that 10% Ethanol addition resulted in reduced HC and CO emissions due to oxygen present in the ethanol. The combustion parameter shows increased heat release rate and reduced cyclic variations with 10% ethanol addition. The optimal ethanol blend with LPG was found to be 10% for better performance and reduced emissions.

Energy and exergy analyses of a hydrogen fueled SI engine: Effect of ignition timing and compression ratio

In the current study energy and exergy analyses of a hydrogen fueled four-stroke spark ignition engine are presented. The energy and exergy analyses are performed based on experimental results conducted on single cylinder, air cooled SI engine which is operated four different compression ratios (ε = 6.6, 7.1 7.6 and 8.1) seven different spark ignition timing, 1600 rpm constant engine speed, lean mixture (ϕ = 0.6) and wide-open throttle conditions. The experimental results, energy and exergy analyses showed that the increase in compression ratio yields an increase in indicated and effective performance parameters of the engine while decrease in exergy destruction is observed. However, the move away of the ignition timing from the optimum value (over or retarded ignition timing) leads to a reduction in engine performance parameters and rise in exergy destruction. Another noteworthy result of this study is that the values of both indicated and effective thermal efficiencies obtained based on experimental studies and the values of both indicated and effective exergy efficiencies obtained by thermodynamic analyses are very close to each other.

Comparative Analysis of a Four Stroke Spark Ignition Engine Performance Using Local Ethanol and Gasoline Blends

This paper presents performance of gasoline engine under locally produced ethanol blended with gasoline. A naturally aspirated four stroke single cylinder spark ignition engine test bed was used at various engine speeds. Different proportion of ethanol-gasoline blends were tested; E0 (0% ethanol and 100% gasoline), E1 (1% ethanol and 99% gasoline), E3 (3% ethanol and 97% gasoline) and E5 (5% ethanol and 95% gasoline). Using a sample size of 100, data were collected and analysed for all the fuel samples tested at different test conditions. The result showed improved engine performance with locally produced ethanol – gasoline blends. The maximum engine performance was attained by E3 at full load throttle condition. The local ethanol-gasoline blends gave a better engine performance over pure gasoline at different test condition. In conclusion, the study proved that locally produced ethanol can be used as a substitute to highly purified ethanol as additive in gasoline.

Dynamics and primary breakup of cavitation bubbles under throttling conditions

Cavitation significantly influences fuel mixture preparation and combustion of IC engines which are the main power source of transportation. Investigation of cavitation in injector and its effect on spray breakup is very important for reduction of emissions and fuel consumption. To study the cavitation dynamics and primary breakup, highly resolved microscopic imaging technique was employed with an enlarged transparent nozzle and a real-sized nozzle under various throttling conditions. Mechanisms of cavitation generation were investigated through the cavitation generation locations and morphologies. The characteristics of the secondary vapor bubbles were also probed by injecting diesel into the liquid based on the differences of density and refraction between liquid and vapor. It was found that under low pressure, dynamic cavitation which developed and receded bi-directionally was observed close to the inlet. Cavitation in the sac and nozzle inlet was mainly throttling induced under low pressure and redirection induced under high pressure, while cavitation at nozzle outlet was mainly redirection induced. Increasing pressure strengthened cavitation at both inlet and outlet, and made the vapor bubbles more compact and deformed. Decreasing throttling effect enhanced the cavitation before weakening. Besides, vapor bubbles collapsed very quickly at the nozzle outlet due to the abrupt pressure reduction.

Optimizing injector nozzle hole layout of a direct-injection spark-ignition engine for wide open throttle condition

The direct-injection concept in gasoline engines induces emission problems due to wall impingement of fuel and lack of mixing time, compared to port-fuel-injection engines. One of the solutions for these problems is optimization of the spray pattern. In this study, injector nozzle arrangement and injection timing were optimized under the wide-open-throttle condition using computational fluid dynamics. An injection pressure of 33 MPa was utilized. Mixture homogeneity, turbulent kinetic energy, and fuel film mass were monitored to evaluate the intermediate optimal design. These variables comprise the objective function. The nozzle arrangement was restricted to consider the processability and reduce computational costs. The KIVA-3V release 2 code was combined with the optimization tool. Depending on the design, the amount of leaking along the outflow to the intake port at the end of the intake process varies, however the injection quantity was maintained for simplification of optimization process. After optimization, the vapor fuel mass fraction in the intake port was considered to form a stoichiometric mixture, and mixture formation and combustion processes were analyzed. The optimal design had a narrower pattern than the reference design and targeted the downward direction when mounted on the engine because it is easy to increase in-cylinder turbulence intensity. The optimal design showed that the mixture homogeneity increased by 0.86% based on homogeneity index and the fuel film mass decreased by 51%, while the turbulent kinetic energy showed no significant change. The exhaust emissions (carbon monoxide, hydrocarbon, soot, nitrogen oxide) were reduced, while the indicated mean effective pressure remained constant.

Effect of Spark Plug Alteration on Performance Using Hydrogen Enriched Gasoline in Si Engine Under Various Loads and Compression Ratios

In this study, change in brake power (BP) of a variable compression spark ignited engine was investigated with different spark plugs and hydrogen enrichment. The tests were carried out with a four stroke, single cylinder, naturally aspirated, variable compression ratio (VCR) engine. Two different compression ratios (CR) of 8.5:1 and 10:1 under %50 part throttle condition were implemented throughout the experiments. Moreover, engine loads of 8 Nm, 13 Nm and 17 Nm were applied to evaluate effects of different spark plugs and hydrogen usage at different engine loads. Copper, iridium and platinum spark plugs were tested for each experiment condition. In addition, hydrogen was added through the intake manifold with flow rates of 0, 2 and 4 lit/min to enhance combustion of VCR engine. According to test results, iridium and platinum spark plug usage, hydrogen addition and higher compression ratio improved BP significantly. This variance occurred more obvious with platinum spark plug usage comparing to iridium spark plug. In addition, effects of spark plug alteration, hydrogen addition and higher CR on enhancement of BP were comparatively lower at higher engine loads.

Comparative assessment of a spark ignition engine fueled with gasoline and raw biogas

The main objective of the study is to explore the potential of raw biogas as an alternative and standalone fuel for gasoline fueled spark ignition (SI) engine. In the current investigation, a single cylinder, spark ignition engine is operated both with gasoline and raw biogas at a compression ratio of 10 under wide open and part throttle conditions. The baseline test is performed with gasoline and subsequent experiments are carried out with raw biogas. The engine performance, combustion and emission parameters are measured over a range of speed variations (1450–1700 rpm). Comparative analysis of the result showed 18% of reduction in brake power, 66% of increase in brake specific fuel consumption and 12% of reduction in break thermal efficiency when the engine is fueled with raw biogas. Because of the non-uniformity in the amount of supplied air and fuel to the engine in every cycle, the coefficient of variation of indicative mean effective pressure and peak pressure (COVpp and COVIMEP) are seen to be higher for biogas. The emission components such as CO and NOx are significantly reduced by 40% and 81.5%, respectively, while, the unburnt hydrocarbon (UHC) and CO2 emission were increased by 6.8% and 40%, respectively.

The Influence of Air Fuel Ratio on the Performances and Emissions of a SINJAI-150 Bioethanol Fueled Engines

In the present work, the effect of variation of air-fuel ratio on performances and emissions SINJAI-150 engine with bioethanol was conducted. Variation of the air-fuel ratio is done by setting the mass flow rate of combustion air using a supercharger. Engine performance was measured using a water brake dynamometer with a variable speed standard from 2000 to 8000 rpm at a fully open throttle condition. The results indicate that the natural intake system produces a relatively rich air-fuel ratio, with an average lambda of 0.68, so that the resulting performance is not maximum. The addition of aspirated 1 and 2 combustion air with the results in the form of average lambda at intervals of 0.8 - 1.1. On the aspirated 2, thermal efficiency increase averaged 50.32%, specific fuel consumption decrease averaged 32.74% and CO and HC emissions reduction average of 7.43 % and 25.77%.

Evaluation of the engine performance and exhaust emissions of biodiesel-bioethanol-diesel blends using kernel-based extreme learning machine

It is known that biodiesel and bioethanol are viable alternative fuels to replace diesel for compression ignition engines. In this study, an experimental investigation is carried out to evaluate the performance and exhaust emissions of a single cylinder diesel engine fuelled with biodiesel-bioethanol-diesel blends. The engine performance parameters evaluated are the brake specific fuel consumption and brake thermal efficiency whereas the exhaust emission parameters evaluated are carbon monoxide, nitrogen oxide, and smoke opacity. Kernel-based extreme learning machine is used to predict the engine performance and exhaust emission parameters of the fuel blends at full throttle conditions. Based on the experimental results, the brake specific fuel consumption is lower while the brake thermal efficiency is higher for the biodiesel-bioethanol-diesel blends. The carbon monoxide emissions and smoke opacity are also lower for these fuel blends. The mean absolute percentage error of the brake specific fuel consumption, brake thermal efficiency, carbon monoxide, nitrogen oxide, and smoke opacity is 1.363, 1.482, 4.597, 2.224, and 2.090%, respectively. Thus, it can be concluded that K-ELM is a reliable method to estimate the engine performance and exhaust emission parameters of a single cylinder compression ignition engine fuelled with biodiesel-bioethanol-diesel blends to reduce fuel consumption and exhaust emissions.

Investigating the effect of MgO and CeO2 metal nanoparticle on the gasoline fuel properties: empirical modeling and process optimization by surface methodology.

The main purpose of this paper is to investigate how to optimize gasoline in order to reduce the emitted pollutants caused by combustion, while the torque and power of the engine reach the maximum capabilities. To optimize gasoline formulation, an ethanol and magnesium oxide (MgO) or cerium oxide (CeO2) mixture was added to gasoline. This study explores the role of main variables such as type of metal nanoparticle additive, engine speed, and throttle on engine performance and exhaust gas emissions through the modeling and optimization methods. Experimental design conducted through the implementation of D-optimal design, taking into account the three main parameters. To review the efficiency of this novel fuel, it was tested by a four-stroke engine connected to a dynamometer and an analyzer, under different controlled environments: speeds of 1500, 2000, 2500, and 3000rpm at both half and full throttle conditions. The analyzed data are the power and torque of the engine, the amount of emitted CO, CO2, HC, and NOx, the octane index, and the viscosity. The analyzed data were calculated and turned into models. Applying the models to data (the optimization process), close correlation between predicted and actual outcomes was found, highlighting the validity of the work. A secondary finding is that the CeO2 mixture used at higher speeds and throttles produces less emissions, while lower speeds and throttles using the MgO mixture produce less emissions.

An investigation on utilization of biogas and syngas produced from biomass waste in premixed spark ignition engine

Syngas and biogas are two typical biofuels generated from biomass wastes through gasification and anaerobic digestion processes, which are considered to be the future fuels for IC engines. In this work, the utilization of biogas and syngas produced from horticultural waste in a premixed spark ignition engine was investigated. An experimentally validated KIVA4-based CFD simulation integrated with CHEMKIN was performed to evaluate engine performance fuelled by syngas and biogas under both single and blended-fuel modes. Effects of ignition timing, hydrogen content in syngas and methane content in biogas on both energetic and environmental performance have been studied. The indicated thermal efficiency (ITE) of syngas fueled engine at wide open throttle (WOT) condition under maximum brake torque (MBT) operation was found to be higher than that of biogas fueled engine, meanwhile, with much lower NOx emission. In addition, a comparison of the engine performance between the single and blended-fuel modes under different syngas mixing ratios was conducted in terms of ITE and NOX emission. The results suggest that the utilization of syngas and biogas under blended-fuel mode can not only maintain the MBT energetic performance under single-fuel mode, but also show its potential in reducing NOx emission and lessening the tendency of knock onset.

Spark discharge and flame inception analysis through spectroscopy in a DISI engine fuelled with gasoline and butanol

Extensive application of downsizing, as well as the application of alternative combustion control with respect to well established stoichiometric operation, have determined a continuous increase in the energy that is delivered to the working fluid in order to achieve stable and repeatable ignition. Apart from the complexity of fluid-arc interactions, the extreme thermodynamic conditions of this initial combustion stage make its characterization difficult, both through experimental and numerical techniques. Within this context, the present investigation looks at the analysis of spark discharge and flame kernel formation, through the application of UV-visible spectroscopy. Characterization of the energy transfer from the spark plug’s electrodes to the air-fuel mixture was achieved by the evaluation of vibrational and rotational temperatures during ignition, for stoichiometric and lean fuelling of a direct injection spark ignition engine. Optical accessibility was ensured from below the combustion chamber through an elongated piston design, that allowed the central region of the cylinder to be investigated. Fuel effects were evaluated for gasoline and n-butanol; roughly the same load was investigated in throttled and wide-open throttle conditions for both fuels. A brief thermodynamic analysis confirmed that significant gains in efficiency can be obtained with lean fuelling, mainly due to the reduction of pumping losses. Minimal effect of fuel type was observed, while mixture strength was found to have a stronger influence on calculated temperature values, especially during the initial stage of ignition. In-cylinder pressure was found to directly determine emission intensity during ignition, but the vibrational and rotational temperatures featured reduced dependence on this parameter. As expected, at the end of kernel formation, temperature values converged towards those typically found for adiabatic flames. The results show that indeed only a relatively small part of the electrical energy is actually used for promoting chemical reactions and that temperature during the arc and kernel phases are influenced to a reduced extent by fuel concentrations.

Performance and emission characteristics of a spark ignition engine fuelled with butanol isomer-gasoline blends

The heavy reliance on petroleum-derived fuels such as gasoline in the transportation sector is one of the major causes of environmental pollution. For this reason, there is a critical need to develop cleaner alternative fuels. Butanol is an alcohol with four different isomers that can be blended with gasoline to produce cleaner alternative fuels because of their favourable physicochemical properties compared to ethanol. This study examined the effect of butanol isomer-gasoline blends on the performance and emission characteristics of a spark ignition engine. The butanol isomers; n-butanol, sec-butanol, tert-butanol and isobutanol are mixed with pure gasoline at a volume fraction of 20vol%, and the physicochemical properties of these blends are measured. Tests are conducted on a SI engine at full throttle condition within an engine speed range of 1000–5000rpm. The results show that there is a significant increase in the engine torque, brake power, brake specific fuel consumption and CO2 emissions with respect to those for pure gasoline. The butanol isomers-gasoline blends give slightly higher brake thermal efficiency and exhaust gas temperature than pure gasoline at higher engine speeds. The iBu20 blend (20vol% of isobutanol in gasoline) gives the highest engine torque, brake power and brake thermal efficiency among all of the blends tested in this study. The isobutanol and n-butanol blend results in the lowest CO and HC emissions, respectively. In addition, all of the butanol isomer-gasoline blends yield lower NO emissions except for the isobutanol-gasoline blend.

Effects of compression ratio and hydrogen addition on lean combustion characteristics and emission formation in a Compressed Natural Gas fuelled spark ignition engine

A single cylinder diesel engine was modified to operate as a Compressed Natural Gas (CNG) fuelled lean burn Spark Ignition (SI) engine. The engine was tested at 1500rpm under wide open throttle condition at different compression ratios over varying equivalence ratios. The optimized compression ratio for CNG operation was found to be 12.5:1 which was further investigated for hydrogen substitution at 5% and 10% on energy basis to study and compare the performance, emission and combustion behavior of CNG fuelled lean burn SI engine. The brake thermal efficiency and brake power output increases with rise in compression ratio and achieved a peak brake thermal efficiency of 30.2% with 12.5:1 compression ratio and above a critical value of 12.5:1, the improvement was small when compared to the increase in emissions. Wide flammability limits of hydrogen enable ultra-lean combustion thereby extends the lean limit of operation to an equivalence ratio of 0.42 with 10% hydrogen addition as compared to 0.50 with neat CNG operation and its anti-knock enhancement makes it advantageous compared to increasing the compression ratio under low load conditions. Hydrogen addition also enhanced the combustion rate, heat release rate and reduced cyclic variations. On the emissions front, hydrogen addition showed reduction in hydrocarbon emissions from 65g/kWh to 6.9g/kWh at an equivalence ratio of 0.5 alongside carbon monoxide and carbon dioxide reduction. Due to retarded ignition timing to avoid knock, the Oxides of Nitrogen (NOx) emission increase was not significant.

Effect of compression ratio and hydrogen addition on part throttle performance of a LPG fuelled lean burn spark ignition engine

A single cylinder CI engine was modified to operate as a LPG fuelled lean burn SI engine. The engine was tested at 1500rpm and 20% throttle opening at compression ratios 9:1, 10:1, 10.5:1 and 11:1 by varying equivalence ratios. The influence of compression ratio and 15% hydrogen substitution on energy basis at the optimal compression ratio of 10.5:1 on performance, emission and combustion behavior were studied and compared. The brake thermal efficiency and brake power output increases with rise in compression ratio, and above a critical value of 10.5:1 the improvement was small when compared to the increase in emissions. The advantage of brake thermal efficiency from higher compression ratio is narrow under low load conditions. The ever increasing load due to the auxiliaries which are likely to grow more require better low load performance and emissions. Wide flammable limits of hydrogen enable ultra-lean combustion and its anti-knock enhancement makes it advantageous compared to increasing the compression ratio at part throttle condition. Hydrogen addition enhanced the combustion rate and heat release rate, reduced cyclic variations, and extended the lean limit of operation. There was perceptible improvement in brake thermal efficiency, brake power and considerable reductions in hydrocarbon, carbon monoxide and carbon dioxide levels. Due to retarded ignition timing the NOx emission increase was not significant.

A coupled thermodynamic and dynamic model of a three cylinder diesel engine: A novel approach for gas exchange process

In this study, a combined thermodynamic and dynamic analysis of diesel engines has been conducted and a simulation program has been prepared for a three-cylinder conceptual engine having 3L swept volume. The dynamic model used in the analysis consists of motion equations of pistons, connecting rods and the crankshaft. The dynamic model involves the hydrodynamic and asperity frictions as well as the gas forces and moments. The thermodynamic aspect of the analysis has been modelled by replacing the idealized thermodynamic processes with more realistic processes. In this content, the gas pressure in the cylinder during compression and expansion periods was calculated at polytrophic conditions by means of the first law of the thermodynamics which comprises the heat generation in the cylinder and the heat loss to the cylinder walls. The gas pressures in the cylinder during the intake and exhaust periods have been mathematically modeled by setting a relation between mass variation of the gas in the cylinder and pressure difference in and out of the cylinder. Pressure, temperature and mass variations in the cylinder were found to be compatible with expectations. The numerical results of the mathematical model of intake and exhaust processes have also been compared with experimental data obtained from a test engine and found to be compatible as well. Via the prepared simulation program, the performance of the engine was tested at a constant throttling condition (constant heat input) and at a constant speed. Results obtained from simulation tests were found to be compatible with physical and practical situations. At constant heat input test conducted at 1460J/cycle heat input, the optimum torque, power and total thermal efficiency of the conceptual engine were determined as 105Nm, 25.7kW, and 30.15% respectively while the engine speed and intake manifold pressure were 244.5rad/s and 1.3bar. At constant speed testing conducted at about 250rad/s, the optimum torque, power and the effective thermal efficiency of the conceptual engine were determined as 158Nm, 39.7kW and 34% respectively while the intake manifold pressure is 1.6bar.

Cycle by cycle variations of LPG-gasoline dual fuel on a multi-cylinder MPFI gasoline engine

ABSTRACTCombustion stability of a multipoint port fuel injection spark ignition engine working on liquefied petroleum gas (LPG)-gasoline dual fuel mode of operation was analysed. LPG-gasoline ratio was varied from 0 to 100% by controlling the injector signals at wide open throttle condition and 3000 RPM. Increasing LPG ratio will give higher peak pressure and higher indicated mean effective pressure (IMEP) because of the higher flame propagation speed of LPG. The experiment showed that maximum pressure will occur nearer to top dead centre when compared to gasoline. Fluctuation in maximum pressure is higher for LPG and is minimum for 50% LPG. Time return map showed that combustion instabilibity will be more for 100% LPG and is less for 50% LPG. Coefficient of variation of IMEP and maximum pressure for gasoline is higher than LPG. With 100% LPG, NOx emission is almost three times that of gasoline. Hence it can be concluded that 50% LPG will give the better combustion characteristics when compared to other fuel blends.

Review of the coal-fired, over-supercritical and ultra-supercritical steam power plants

The article presents a review of developments of modern high-capacity coal-fired over-supercritical (OSC) and ultra-supercritical (USC) steam power plants and their implementation. The basic engineering solutions are reported that ensure the reliability, economic performance, and low atmospheric pollution levels. The net efficiency of the power plants is increased by optimizing the heat balance, improving the primary and auxiliary equipment, and, which is the main thing, by increasing the throttle conditions. As a result of the enhanced efficiency, emissions of hazardous substances into the atmosphere, including carbon dioxide, the “greenhouse” gas, are reduced. To date, the exhaust steam conditions in the world power industry are p 0 ≈ 30 MPa and t 0 = 610/620°C. The efficiency of such power plants reaches 47%. The OSC plants are being operated in Germany, Denmark, Japan, China, and Korea; pilot plants are being developed in Russia. Currently, a project of a power plant for the ultra-supercritical steam conditions p 0 ≈ 35 MPa and t 0 = 700/720°C with efficiency of approximately 50% is being studied in the EU within the framework of the Thermie AD700 program, project AD 700PF. Investigations in this field have also been launched in the United States, Japan, and China. Engineering solutions are also being sought in Russia by the All-Russia Thermal Engineering Research Institute (VTI) and the Moscow Power Engineering Institute. The stated steam parameter level necessitates application of new materials, namely, nickel-base alloys. Taking into consideration high costs of nickel-base alloys and the absence in Russia of technologies for their production and manufacture of products from these materials for steam-turbine power plants, the development of power plants for steam parameters of 32 MPa and 650/650°C should be considered to be the first stage in creating the USC plants as, to achieve the above parameters, no expensive alloys are require. To develop and construct OSC and USC head power plants, joint efforts of the government, experts in power industry and metallurgy, scientific institutions, and equipment manufacturers are required.

Design Procedure of a Movable Pintle Injector for Liquid Rocket Engines

Variable-area injectors are suitable choices for developing throttleable rocket engines because it is difficult to efficiently control thrust when fixed-area injectors are used. A pintle injector is a variable-area injector that can control the mass flow rate of propellants, thereby replacing a large injector plate having several injector elements with a single injector unit. To achieve proper performance under all throttling conditions, a design procedure was established for a pintle injector based on spray characteristics. The spray angle and Sauter mean diameter of the droplets were critical performance parameters. In spray experiments using water and air as simulants under atmospheric conditions, backlight imaging and laser-diffraction methods were used to measure the spray angle and Sauter mean diameter. The velocity ratio, nondimensionalized opening distance, and Weber number were considered as major nondimensional numbers. Empirical correlations were formulated between performance parameters and nondimensional numbers; these correlations were applied to the design procedure herein. Consequently, a 500 N combustor with a pintle injector was designed using this procedure. A control plan for the pintle-opening distance under lower throttling conditions was also obtained for designing a small combustor. Furthermore, the most sensitive parameters in the injector geometry were confirmed via sensitivity analysis.