In-cylinder Flow Characteristics Research Articles

Understanding the role of methanol as a blended fuel on combustion behavior for rotary engine operations

Methanol, being one of the most promising carbon-neutral fuels, has the potential to enhance the fuel mixture homogeneity of gasoline rotary engines, thereby improving engine performance. This study, based on computational fluid dynamics model, investigates the in-cylinder flow, combustion, and emission characteristics under various methanol blending ratios, ignition timings, and equivalence ratios. At the methanol energy blending ratio of 10 %, a more extensive and efficient operating range is observed across different ignition timings and equivalence ratios, attributed to the higher diffusion and combustion rates. An increase in in-cylinder temperature enhances the complete conversion of HC. However, higher proportions of methanol are disadvantageous for the combustion process due to methanol's lower heat value and higher latent heat of vaporization. Thus, the optimal ignition timing was determined to be 30°EA BTDC. At this optimal ignition timing, the cylinder shows higher average turbulent kinetic energy and radical content compared to the ignition timing at 50° EA BTDC. Specifically, the concentrations of OH, H, and O free radicals increase by 12.40 %, 14.77 %, and 13.91 % respectively, leading to more complete initial flame kernel expansion. It is notable that emissions of CO, HC, and NOx are all reduced. The study further explores the influence of the equivalence ratio on the combustion process. At an equivalence ratio of 0.9, there is an earlier peak in the maximum cylinder pressure rise rate and the highest generation of O and OH, with a shorter main combustion period and concentrated heat release. This achieves economically viable operation for rotary engines, indicating a 2.122 % improvement in thermal efficiency and a reduction in fuel consumption to 375.537 g kW−1 h−1.

Computational analysis of piston shape effects on in-cylinder gas flow, fuel-charge mixing, and combustion characteristics in a two-stroke rod-less spark ignition opposed-pistons engine

Compared with the traditional in-cylinder direct-injection spark ignition engine, the side-injection and side-spark-ignition characteristics of the two-stroke opposed-piston engine increase the ignition kernel offset and flame propagation distance. Increasing the flame propagation speed can to some extent solve the drawbacks caused by the non-central arrangement of spark plugs. The combustion chamber structure plays a crucial role in gas flow, fuel-charge mixing, and combustion characteristics. Therefore, three pistons were designed and comparatively analyzed in this study. The results show that: The pancake piston is beneficial to maintaining the intake swirl strength due to its simple and smooth spherical arc structure. The swirl strength of the pit and pit-guided piston decreases obviously, and the tumble strength can be maintained well. Compared to pancake and pit-guided pistons, the average TKE for the pit piston increased by approximately 25%, with a more concentrated distribution at the spark timing. The pancake piston exhibits the best scavenging performance, reducing the residual exhaust gas ratio by 2.1% and fresh air loss by 3.3% to the pit piston. A stable ignition core can be formed at the spark timing, but significant differences are observed in the flame propagation process for three pistons. Compared to the pit-guided piston, the pit piston has a 0.3% decrease in the indicated thermal efficiency, but a 13.1% decrease in combustion duration, which reduces knock tendency.

0/1 and 3 - dimensional cold flow analysis of a diesel engine: A case study

Gas motion in the engine cylinder plays a critical role in diesel engines' air-fuel mixing and combustion processes. Moreover, it influences the engine's performance, emissions, and heat transfer. The intake air motion regulates the main phases of the flow in the cylinder, which is characterized by swirl, squish, and turbulence. Inducing swirl and tumble in the intake process provides high turbulence levels at ignition, resulting in more effective flame speeds and better combustion for lean air-fuel ratios or with EGR. Computational fluid dynamics (CFD) software is used to enhance in-cylinder flow characteristics. In this study, a cold flow simulation of a naturally aspirated, direct injection diesel engine was conducted with different piston bowls using AVL Fire M R2022.2. Swirl, tumble, and TKE parameters were investigated to make a detailed analysis of the in-cylinder flow for the relevant engine. Contrary to the expectation, the swirl ratio for the Piston B configuration is less than that for the original piston configuration. It causes a decrement of swirl ratio compared to the initial piston geometry and the maximum decrement is about 19%. In both cases, the second peak of TKE corresponding to the reverse-squish is around at the -30 CA and the difference between the curves is about ±8%.

Effects of piston crown designs on in-cylinder flow and mixture formation in gasoline direct injection engine under the lean burn condition

In this study, the effects of piston shapes on in-cylinder flow characteristics and mixture formation in the lean condition was analyzed using the PIV method and CFD (CONVERGE v2.4). The four-piston geometries were concave, flat, convex, and base pistons, and the pistons were mounted on a GDI engine with transparent quartz. To quantify in-cylinder flow characteristics, the mean velocity, tumble ratio, turbulent kinetic energy, and tumble center were calculated. In addition, to analyze the effects of the difference in piston shapes in detail, the velocity fraction was calculated by dividing the cylinder area into three. In-cylinder flow was compared for the case without injection and the case with injection. There were four timed injections at C.A. 420°, 480°, 540°, and 600°, and the mixture characteristics were investigated in the cases of 480° and 600° injection. In the intake process and early compression process, there was no significant difference in the quantitative values for the shape of the piston regardless of the presence or absence of injection. However, the effects of the piston crown designs increased in the later compression process. As a result, the highest turbulent kinetic energy was found using a flat piston with a relatively high tumble ratio and swirl ratio in the absence of injection. The mixture formation was similar for all piston crown designs when injected at the crank angle of 480°. However, when the crank angle of 600° was injected, a stagnant fuel area was formed using the base-type piston, so it was difficult to secure sufficient fuel near the center of the cylinder.

A study on in-cylinder flow characteristics of crank-rocker engine using CFD and PIV

In this study, a thorough in-cylinder flow analysis is performed to visualize the actual flow traits through the intake & compression strokes of the crank-rocker engine. For this purpose, particle image velocimetry (PIV), which is a method for flow visualization is used to better understand the air–fuel mixing and flow properties. CFD was also performed with Re Normalized Group k-ε model to validate the results using the widely used commercial software CONVERGE. The results of PIV experiments were in agreement with the CFD results to the highest degree. The tumble and TKE were analyzed at cold-flow conditions and the initial and boundary conditions were used in CFD analysis to validate the results. This study helps in understanding the flow characteristics of crank-rocker engine numerically and experimentally.

Combined effect of intake pipe deflection and injection timing on In-cylinder flow and combustion characteristics of a gasoline direct injection Wankel rotary engine

To improve the fuel–air mixing and burning processes in a rotary gasoline engine to achieve efficient combustion, this paper used a computational fluid dynamics method to establish numerical simulation models for the in-cylinder flow and combustion of the rotary engine with a peripheral intake system. The effects of the intake pipe deflection angle and fuel injection timing on the in-cylinder flow, fuel distribution, and combustion characteristics were studied. The results showed that deflecting the intake pipe to the left generated a stronger tumble flow in the cylinder to effectively increase the turbulence intensity. A greater deflection angle provided a more obvious improvement. Moreover, deflecting the intake pipe to the left made the fuel distribution more towards the rear part of the combustion chamber and a more uniform fuel distribution in the cylinder. The spray impingement effect on the rotor surface was also greatly improved. Fuel injection timing also has a great impact on the mixing process of the combustible mixture in the cylinder. More advanced fuel injection timing resulted in longer mixing time of the fuel and air to make the mixture more uniform. Finally, deflecting the intake pipe to the left significantly increased the in-cylinder peak pressure and improved accumulated heat release. However, these effects became weakened when the fuel injection timing was retarded. Particularly, when the intake pipe was deflected to the left by 10°, the in-cylinder peak pressure increased most with a 27.9% increase compared with the original design. When the intake pipe was deflected to the left by 30°, the turbulent kinetic energy increased most with a 93% increase compared with the original design. The intake pipe was deflected by 10° to the left and the fuel injection timing was 250° CA BTDC, which is the most helpful for improving engine performance. This study can provide guidance for design of the injection and intake systems of the rotary engine.

Effects of swirl enhancement on in-cylinder flow and mixture characteristics in a high-compression-ratio, spray-guided, gasoline direct injection engine

In this study, the flow enhancement effects of applying a swirl control valve were investigated with particle image velocimetry and simulation using CONVERGE v2.4 program in a high compression ratio, spray-guided, gasoline direct injection engine. This was followed by analysis of varying the spray structure and the mixture preparation process for different swirl control valve angles. The flow intensity was strengthened in the order of swirl control valve angle 45°, 30°, and 0°, and spark plug gap velocities near TDC were increased 1.89, 4.40, and 6.69 m/s in that order. However, the effect was not significant when it was increased to more than 45°. Also, the swirl-dominant flow and the tumble-dominant flow were differentiated based on the relationship between maximum swirl and tumble ratios. In the swirl dominant flow (swirl control valve angle of 0°), more retarded injection timing produced mixture formation in the order of homogenous to mal-distributed to stratified, whereas in the tumble dominant flow (swirl control valve angle of 45°), the order was homogenous to stratified to mal-distributed. It was determined by characteristic period to which the injection timing belonged, and the characteristic period was defined based on the relationship between the intake valve lift and the piston velocity.

The full-parametric development of the intake ports by using genetic algorithm in a four-valve diesel engine

In-cylinder flow characteristics, which are mainly determined by the intake ports, have a decisive influence on the mixture formation and combustion process of internal combustion (IC) engines. To develop the optimum intake ports in a four-valve diesel engine, the full-parametric design method coupled with genetic algorithm (GA) and artificial neural network (ANN) was adopted in this study. Different from previous studies, the full-parametric templates for the tangential and helical ports were established. Then, to improve the precision of the CFD result which was used to train the ANN, the near-wall region affected by viscosity was resolved by the “enhanced wall treatment” during the simulation process. Besides, considering the interaction between the outlets of adjacent intake ports in the four-valve engine, the ANN was divided into three parts to better predict the flow performance of the combined intake ports. Finally, the developed intake ports based on ANN and GA were machined to the flow box and validated by the steady flow test. The low deviation of 4.71% in swirl ratio between the design target and the experiment result confirms that this method can be well applied to the development of the intake ports in a four-valve diesel engine.

Effects of operating parameters on in-cylinder flow characteristics of an optically accessible engine with a spray-guided injector

This study investigated the cycle-to-cycle variation of a spark-assist high-compression-ratio spray-guided direct-injection two-cylinder optically accessible engine. The cycle-to-cycle variation was evaluated by calculating the mean velocity, tumble ratio, tumble center, and effective radius using the PIV measurement results. Under all experimental conditions, the mean velocity continuously decreased owing to the momentum loss from the intake to compression strokes. A low COV was observed within the high-velocity region, and the effective radius decreased as rotational flow formed regardless of the engine operating conditions. As the engine speed increased, owing to the high piston speed, the in-cylinder flow intensified. However, the effective radius and tumble ratio were similar during the compression stroke. As the intake pressure increased from 0.8 to 1.3 bar, the mean velocity and tumble ratio slightly increased. Moreover, the effective radius decreased slightly during the compression stroke. As the IVO timing was retarded, during the intake stroke, the structure of the in-cylinder flow changed dramatically. Rapid momentum dissipation occurred after the intake air inflowed strongly, resulting in relatively weak rotational flow compared to the reference and advanced IVO timing conditions.

Effects of Intake Pipe Deflection on In-Cylinder Flow and Combustion Characteristics of a Direct Injection Rotary Gasoline Engine

Effects of Intake Pipe Deflection on In-Cylinder Flow and Combustion Characteristics of a Direct Injection Rotary Gasoline Engine

In-cylinder gas flow characteristics study of CI engine under motoring and pre-ignition firing conditions using a high-speed PIV

Engine properties such as engine speed and fuel injection quantity may affect the swirl flow of diesel engines. In this paper, experiments are conducted at two engine rpm and various operation conditions. For instance, motoring with no fuel injected, pre-ignition firing conditions, in addition to different fuel quantities. In this experimental analysis, PIV technique is performed to observe the flow patterns of the charging gas. The obtained results indicate that the swirls behavior is similar under all operation conditions during the intake and compression strokes regardless of the engine speed. In comparison to pre-ignition firing process, generation of more swirl centers has been observed for both engine speeds i.e., 1000 rpm and 1500 rpm under motoring conditions. Additionally, at CA of 610 deg., the swirls centers were maintained for all configurations except for motoring conditions and lowest fuel quantity of 2 mg. Moreover, during expansion strokes for both engine speeds the least magnitude of velocity-vectors was observed under motoring condition. Nevertheless, the higher mean velocity-vectors among that of expansion stroke was observed under pre-ignition firing configuration. The obtained results suggest that, the movement of the induced swirl centers across the piston cavity during expansion to exhaust strokes and increasing the engine speed corresponded to an increase in the mean-velocity, swirl ratios, and TKE.

Influence of Intake Pipe Deflection Angle on In-Cylinder Flow and Combustion Characteristics of a Rotary Engine

Abstract Intake pipe design is important for rotary engine performance due to great influence on in-cylinder flow and combustion characteristics. This paper analyzes the effect of intake pipe deflection angle on the performance of a gasoline rotary engine. In the parametric study, the intake pipe is deflected from the left to the right with a 10 deg interval and the maximum deflection range of 30 deg at each side. A computational fluid dynamics numerical simulation model of the rotary engine is established. The simulation results show that when the intake pipe is deflected to the left from the original design, the engine volumetric efficiency first increases and then decreases with an increasing deflection angle. During ignition, the turbulent kinetic energies in the cylinder increase with an increasing deflection angle. When the intake pipe is deflected to the left by 30 deg, the turbulent kinetic energy is increased by 85.9% compared to the original design. The peak cylinder pressures first increase and then decrease with an increasing deflection angle. When the intake pipe is deflected by 10 deg to the left, the peak cylinder pressure is 9.3% higher than that of the original design. The maximum NOx emission can be increased by 4.8% and the minimum NOx emission can be decreased by 13.3%. It is found that deflecting the intake pipe to the left enhances the tumble effect and increases the combustion velocity. Overall, deflecting the intake pipe to the right is less effective than deflecting to the left. This analysis provides a comprehensive understanding on intake pipe design for rotary engines.

Impingement-Induced Stability Analysis of Intake Manifold Air Jets Using High Speed PIV and POD

The flow stability induced by the impingement of gas jets exiting from the intake manifold affects the in-cylinder flow characteristics of internal combustion engine. Using high-speed planar particle image velocimetry (PIV) with proper orthogonal decomposition (POD) analysis, an investigation was conducted to reveal the spatio-temporal characteristics of annular gas jets impinging in a region between the exits of two intake valves. Unique flow behaviors are identified where strong initial interaction of impinging jets appears near the valve exit as a result of fierce flow vorticity competition in both clockwise and counter-clockwise directions. This mixing zone exhibits strong fluctuations in the angle of the merged gas jet. Flow vorticity and merged jet angle are highly correlated with each other, and the quasi-periodical behavior of the jet impingement is linked to the kinetic energy dissipation. In addition, using POD, the underlying flow structures show large-scale rotating structures with translation which are responsible for the quasi-periodical behavior. In summary, three types of flow stability can be identified resulting from different levels of induced impingement: one-way interaction of single jet flow case, two-way interaction of dual impinging jets with equal flow magnitude, and transitional one-way interaction of dual impinging jets with unequal flow magnitude.

Experimental and Numerical Validation of In-Cylinder Combustion Analysis of DI Diesel Engine

The major factors affecting the process of combustion in a single cylinder diesel engine is in-cylinder fluid flow characteristics. Better fuel-air mixing and combustion rates in diesel engine are primarily enhanced by the fluid flow. The fluid flow prior to combustion process in DI diesel engines travel through induction process and further gets improvised during the compression process. Therefore, it is compulsory to understand the fluid flow motion inside the cylinder in designing the different bowl-in-piston geometries with the most appropriate operating and emission characteristics. A better spatial distribution is required for the injected fuel throughout the entire space of combustion geometry in DI diesel engine, to obtain a better combustion with lesser emission. In order to effectively make use of gas flows it is mandatory to match the piston bowl geometry with fuel spray characteristics. For obtaining better combustion, matching of combustion chamber geometry, fuel injection and gas flows plays prominent role. But it is evident that piston bowl geometry plays a significant role on flow of compressed air when piston moves from BDC to TDC i.e., before the start of combustion, resulting in proper mixing, better vaporization and atomization of fluid particles. When compared with other combustion chambers, Off-set bowl in the absence of central projection with sharp edges provide higher swirl number. Higher these whirl number lesser will be the soot emission at the expense of higher NOx level.

Experimental and numerical study the effect of EGR strategies on in-cylinder flow, combustion and emissions characteristics in a heavy-duty higher CR lean-burn NGSI engine coupled with detail combustion mechanism

In order to study the effects of exhaust gas recirculation (EGR) strategies on in-cylinder flow, performance, combustion and emissions characteristics in a heavy-duty higher compression ratio (CR) lean-burn natural gas spark ignition (NGSI) engine. In the first stage, a detailed three-dimensional (3-D) full-scale cylinder part (including detailed intake port and exhaust port) is established based on the actual combustion chamber. Then some cases were simulated by commercial CFD code coupled with the detailed combustion mechanism and validated against the measured data. In the second stage, a sensitivity analysis of the EGR rate on in-cylinder temperature, emissions under different crank angles in 3-D, and performance of a heavy-duty higher CR (13.6) engine fueled with 99% methane content is discussed. The results show that the production of NOx is related to the mass fraction of high-temperature gas in a specific section of the cylinder. The larger the mass fraction of high-temperature gas, the more NOx emissions are generated. Besides, NOx is generated on the flame front and continuing to be generated inside the flame surface. The faster the temperature inside the flame surface decreases, the smaller the amount of NOx generation is. Furthermore, the model and these data in the paper can be applied to evaluate and optimize the energy distribution by changing different technologies or strategies in the future. In addition, 3-D data can provide a basis for the quantitative relationship between the EGR rate and combustion rate, NOx generation in the format of 1-D.

A study on in-cylinder flow field of a 125cc motorcycle engine at low engine speeds

The in-cylinder flow characteristics of a four-stroke, four-valve, pent-roof small engine of motorcycle at engine speeds from 2000 rpm to 4000 rpm were studied using computational fluid dynamics (CFD). The aim of this study was to investigate the in-cylinder flow characteristics of small engines, including tumble, swirl, turbulent kinetic energy (TKE), angular momentum, in-cylinder air mass, turbulent velocity, turbulent length scale, and air flow pattern (in both intake and compression strokes) under motoring conditions. The engine geometry was created using SolidWorks, then was exported and analyzed using CONVERGE, a commercial CFD method. Grid independence analysis was carried out for this small engine and the turbulence model was observed using the renormalized group (RNG) k-ɛ model. The pressure boundary conditions were used to define the fluid pressure at the intake and exhaust of the port. The results showed that the increase in the engine speed caused the swirl flow in the small engine to be irregularly shaped. The swirl flow had a tendency to be stable and almost constant in the beginning of the compression stroke and increased at the end of compression stroke. However, the increase of in engine speed had no significant effect on the increase in tumble ratio, especially during the intake stroke. There was an increase in tumble ratio due to the increase in engine speed at the end of compression stroke, but only a marginal increase. The increase in engine speed had no significant effect on the increase in angular momentum, TKE, or turbulent velocity from the early intake stroke until the middle of the intake stroke. However, the angular momentum increased due to the increase in engine speed from the middle of the intake stroke to the end of compression stroke, and the angular momentum achieved the biggest increase when the engine speed rose from 3000 to 4000 rpm by 10 % at the end of the intake stroke. The increase in engine speed caused an increase of TKE and turbulent velocity from the middle of intake stroke until the end of compression stroke. Moreover, the biggest increase of TKE and turbulent velocity occurred when the engine speed rose from 3000 to 4000 rpm at the middle of intake stroke around 50 % and 25 %, respectively. Turbulent length scales appeared to be insensitive to increasing engine speed, especially in the intake stroke until 490 °CA. From that point, the value of the turbulent length scale increased as engine speed increased. The biggest increase in the turbulent length scales occurred when the intake valve was almost closed (around 20 %) and the engine speed was within two specific ranges (2000 to 3000 rpm and 3000 to 4000 rpm). Regarding the effect of engine speed, there were no significant effects upon the accumulated air mass in the small engine. The increase in engine speed caused an increase of turbulence in the combustion chamber during the late stages of the compression stroke. The increase in turbulence enhanced the mixing of air and fuel and made the mixture more homogeneous. Moreover, the increase in turbulence directly increased the flame propagation speed. Further research is recommended using a new design with several types of intake ports as well as combinations of different intake ports and some type of piston face, so that changes in air flow characteristics in small engines can be analyzed. Finally, this study is expected to help decrease the number of experiments necessary to obtain optimized systems in small engines.

Investigation of In-Cylinder Engine Flow Quadruple Decomposition Dynamical Behavior Using Proper Orthogonal Decomposition and Dynamic Mode Decomposition Methods

In order to study the in-cylinder flow characteristics, one hundred consecutive cycles of velocity flow fields were investigated numerically by large eddy simulation, and the proper orthogonal decomposition (POD) algorithm was used to decompose the results. The computed flow fields were divided into four reconstructed parts, namely mean part, coherent part, transition part, and turbulent part. Then, the dynamic mode decomposition (DMD) algorithm was used to analyze the characteristics of the reconstructed fields. The results show that DMD method is capable of finding the dominant frequencies in every reconstructed flow part and identifying the flow structures at equilibrium state. In addition, the DMD results also reveal that the reconstructed parts are related to each other through the break-up and attenuation process of unstable flow structures, while the flow energy cascade occurs among these parts through different scale vortex generation and dissipation process.

Multi-plane time-resolved Particle Image Velocimetry (PIV) flow field measurements in an optical Spark-Ignition Direct-Injection (SIDI) engine for Large-Eddy Simulation (LES) model validations

In-cylinder flow characteristics play a significant role in the fuel–air mixing process of Spark-Ignition Direct-Injection (SIDI) engines. Typically, planar Particle Image Velocimetry (PIV) is used to measure a representative velocity field sectioning through the center plane of the engine cylinder. However, a single flow field offers very limited perspective regarding the Three-Dimensional nature of the flow fields. Since the in-cylinder flow is stochastically complex, large datasets of flow field measurements along multiple planes are needed to provide a complete panoramic understanding of the flow dynamics. In this study, a high-speed PIV is applied to measure the crank-angle resolved flow fields inside a single-cylinder four-valve optical SIDI engine. Five flow fields along different tumble planes are captured. These five planes include two orthogonal planes cutting through the spark plug tip, two parallel planes sectioning through middle point of the intake and exhaust valves, and one plane through the centers of two intake valves. In addition, numerical computations are carried out with Large-Eddy Simulation (LES) model in CONVERGE. With the guidance from multi-plane PIV measurements, a novel validation approach is proposed in this study. The quantitative analysis and comparison between LES simulations and PIV experiments are divided in terms of global and local comparison indices. The global comparison indices provide a quantitative single value to quickly check the overall similarity of velocity directions and magnitudes between PIV and LES results of a specific individual plane. The local comparison indices further evaluate the similarity between the flow fields of LES and PIV point by point to identify any dissimilar regions and vortex features, which are likely to indicate the complex flow structures at low-speed regions. In summary, not only can the combined data analysis approach provide a reliable way for LES model validations, it can also reveal the physical quantifications of the complex in-cylinder flow characteristics.

A Comparative Analysis of In-Cylinder Flow, Heat Transfer and Turbulence Characteristics in Different Type Combustion Chamber

Recently some studies have been carried out on combustion chamber design for diesel and gasoline engines; however, they routinely used piston bowl model approach, which may neglect interactions with cylinder head design. Fluid motion within the cylinder of internal combustion engines has a significantly influence on the combustion process and engine efficiency. The aim of this study two different geometries of the combustion chamber of internal combustion engine were compared in terms of in cylinder flow and heat transfer during the intake process. For this, complete calculations of the intake stroke were performed under realistic operating conditions and heat transfer, velocity and turbulence flow fields obtained in each combustion chamber investigation detail. They were solved with finite volume method and ANSYS-Fluent 12.0 commercial code. The findings include using k-e turbulence model and dynamic mesh generation model for different crank angle. The result of studies show that flow structure and turbulence intensity are affected on combustion chamber geometries. Also, the pent-roof type combustion chamber configuration was found to generate turbulence intensity more efficiently than the conventional type combustion chamber.

Effects of hydrogen enrichment and injection location on in-cylinder flow characteristics, performance and emissions of gaseous LPG engine

In this work, a fully instrumented four-cylinder spark ignition engine was converted into bi-fuel gaseous engine to run with LPG and hydrogen blends. Hydrogen, as supplementary fuel, was introduced into intake manifold using manifold port injection technique. Two configurations for hydrogen fueling system were taken into consideration. The first system is based on separated port inputs of fuels method. In fact, hydrogen is injected at the intake manifold plenum level. The second is based on the same port inputs of fuels method. LPG and hydrogen were streamed simultaneously through a two-input air/gas mixer. Computational fluid dynamic (CFD) simulations were performed in order to study the effect of hydrogen injection location on in-cylinder flow characteristics and mixture homogenization using the 3D CFD code SolidWorks Flow Simulation “SWFS”. CFD investigation was aimed at analyzing the velocity, turbulence structures and hydrogen diffusion into the mixture at quasi-steady and unsteady engine conditions during the intake process using the two hydrogen fueling configurations. The outcomes from the simulations were used to justify the selection of separated LPG-H2 inputs as the hydrogen fueling system.Experimental investigations are carried out to validate the adequate fueling system and identify the hydrogen enrichment effect on LPG gaseous engine performances and emissions. Experimental measurements were achieved by blending a percentage of hydrogen (0%, 5%, 10%, 15% and 20% in volume) with LPG and supplied to the engine. As results, the brake power was increased using 20% hydrogen addition ratio by 17.5% compared to standard pure LPG operation. Brake thermal efficiency was improved by 4.5% at maximum engine speed. A decrease of carbon dioxide emissions was attained by 15.1% at maximum engine torque (2500 rpm). There was considerable reduction in hydrocarbon levels.