Combustion Pressure Research Articles

Vehicle Intermittent Idle Shake: Mechanism and Influence Factors

This paper studies the mechanism and influencing factors of the intermittent shaking of a vehicle in idle conditions and explores methods to suppress the idle shake of a vehicle. A full vehicle model including an engine crank-link mechanism is established. Taking a vehicle with intermittent idle shake as an example, the causes of the intermittent idle shake of the vehicle are investigated. The study shows that the intermittent idle shake of the vehicle is caused by the beat vibration, which is due to the unbalance of the crankshaft of the engine and the rotating turbine of the torque converter, and the near rotational speeds of these two rotating parts. In addition, a parametric model of cylinder pressure is presented. The effects of abnormal cylinder pressure (abnormal amplitude, abnormal ignition phase and abnormal fluctuating rate) on the idle shake are analyzed respectively. It is found that changes of combustion pressure in cylinder may also cause intermittent idle shake of the vehicle. Finally, the measures to attenuate the intermittent idle shake of vehicle are presented.

Ethanol Inhomogeneous Lean Combustion Under Different Ambient Temperatures and Pressures with Hydrogen Enrichment

ABSTRACT The effects of different ambient temperatures and pressures on the combustion of hydrogen-enriched liquid ethanol spray were studied in a constant-volume vessel, using experimental and numerical methods. The inhomogeneous combustion experiment was conducted under ultra-lean conditions at an overall equivalence ratio of 0.3 (33% spray ethanol/67% premixed hydrogen). The spray and flame images and combustion pressures were obtained. The spray simulation models used were the RANS k-ε turbulence model, KH-RT model, and wall film interaction model. The experimental results showed that the inhomogeneous combustion of the liquid ethanol spray can be divided into two stages: a rapid-burning and a slow-burning stage. The slow-burning stage was sensitive to changes in ambient temperature and pressure. Combustion duration decreased with elevated pressure and declined temperature. Under low pressure and medium temperature conditions, the flame reached its fastest propagation speed. The simulation results showed that the fuel concentration and concentration gradient around the ignition position are the key factors that affect inhomogeneous lean combustion. When the equivalence ratio was over 0.8 around the ignition position and the gradient of the equivalence ratio increased no less than 0.1/mm, the optimal combustion characteristics were achieved.

The performance of reaction mechanism in prediction of the characteristics of the diffusive-thermal oscillatory instability of methane–hydrogen–air burner-stabilized flames

In this work the performance of various detailed reaction mechanisms of combustion of methane–hydrogen fuel mixtures is studied. The investigation is focused on the burner stabilized flame configuration and is undertaken for the normal pressure conditions, which is a starting point for the analysis of the combustion chemistry at elevated pressures met in rocket engine chambers. The study presents the experimental setup, computational approach and results of comparison, which allow us to access the properties of complex combustion systems in variety of dynamical regimes. The comparison of the predicted and measured characteristics of these regimes is used to test the performance of the reaction models. In particular, the critical behavior, e.g. for blow-up, onset of pulsations and quasi-steady flame front propagation and bifurcation between these regimes may be used to characterize and to study properties of combustion systems with mixed fuels. A neutral stability boundary for onset of pulsations is suggested to be used in this study. A method for automatic identification of the boundary is proposed and implemented with several detailed mechanisms. Although for pure methane the results look acceptable, they show gradual divergence with the increase of percentage of hydrogen addition. Significant quantitative differences between experiments and modeling with respects to frequencies of oscillations are reported even for 2:1 ratio of hydrogen to methane in the unburned mixture. The results of the work indicate that current reaction mechanisms need to be improved in order to gain the quantitative predictability of methane–hydrogen–air combustion at normal pressure before proceeding to the conditions fuel-oxygen high pressure combustion more relevant for rocket chamber.

Strategy for improving the energy output efficiency of TKX-50: introduction of nitroamine explosives

ABSTRACT TKX-50 has attracted the attention of many researchers because of its low sensitivity and high energy characteristics. However, the experimental results show that there is a big gap between the energy level of TKX-50 and the theoretical value. Introducing nitroamine explosives RDX or HMX to stimulate the energy release of TKX-50 is of great significance for improving the energy release efficiency of TKX-50 and expanding its application in the field of energetic materials. In this paper, the properties of different TKX-50/RDX and TKX-50/HMX samples were investigated by thermal analysis and ignition combustion experiments. The results show that RDX has a more obvious catalytic effect on TKX-50. Adding 50% RDX reduces the peak thermal decomposition temperature of TKX-50 from 241.7°C to 218.7°C. At the same time, the flame propagation, maximum combustion pressure, and the pressurization rate of different samples during combustion were analyzed, and the reaction mechanism between RDX (or HMX) with TKX-50 was obtained. Because of the different catalytic effects of RDX and HMX on TKX-50, a strategy was proposed to construct the core-shell structure of TKX-50 to improve the reaction characteristics and energy release efficiency of TKX-50.

The effect of biogas and dimethyl ether on the thermal characteristics of a dual‐fuel diesel engine: A numerical study

AbstractThis investigation used the Diesel‐RK simulation program to carry out a numerical analysis of the effects that dual‐fuel mixes have on the combustion, performance, and emissions of a dual‐fuel diesel engine. It applied the multizone combustion model, and the controlling equations were solved for each individual combustion region. The engine characteristics were examined under the following scenario: it was initially powered by single‐fuel regular diesel (DF), then it switched to dual‐fuel use with 20% biogas, and then it was changed again with the use of 30% dimethyl ether (DME). On this basis, the mentioned biogas and DME ratios were used. The results showed that combustion pressure for the operation of 30% DME and 20% biogas was reduced by 2.45% and 9.57%, respectively, with respect to diesel fuel alone. The Sauter mean diameter (SMD) of the droplets was reduced by 12.6% for 30% DME and 16.2% for 20% biogas. Heat release and brake thermal efficacy (BTE) were reduced slightly with the use of biogas or DME in comparison with DF. The brake‐specific fuel consumption (BSFC) increased by 15.27% and 8.34%, with 30% DME and 20% biogas respectively due to the difference in the energy content of the tested fuels. Nitrogen oxide emissions decreased by 2% and 28% for the operation of 30% DME and 20% biogas, respectively. The summary emission equation (SE), which describes the combination of NOx and PM emissions, decreased by 4.23% and 5.40% with 30% DME and 20% biogas respectively. Based on the results, this paper recommends the use of 20% biogas with diesel rather than 30% DME. The current findings matched well with other scientists' results.

Performance optimization design of trapped vortex combustion chamber with a sand dune blunt body

In an effort to enhance the performance of the trapped vortex combustion chamber, this paper improved the trapped vortex combustion chamber and proposed a sand dune trapped vortex combustion chamber. Firstly, the effects of different inlet velocities and equivalence ratios on the performance of the two combustion chambers were analyzed. The results showed that under the same operating conditions, the performance of the sand dune trapped vortex combustion chamber was better than that of the trapped vortex combustion chamber. Then, a central composite design (CCD) response surface experimental method was adopted to optimize the structure of the sand dune trapped vortex combustion chamber in detail. The windward angle (α), leeward angle (θ), and rear blunt body height (h) were used as influencing factors. The combustion efficiency (η), pressure loss (δ*), and NOx emissions were used as response variables. Quadratic polynomial regression equations for η, δ*, and NOx emissions were established respectively. Subsequent to this, the expected value function method was employed for multi-objective optimization of the three regression equations. After optimization, compared with the original trapped vortex combustion chamber, the combustion efficiency of the sand dune trapped vortex combustion chamber increased from 87.56 % to 95.41 %, NOx emissions decreased from 747.94 ppm to 386.35 ppm, the outlet temperature distribution factor (OTDF) decreased from 0.21 to 0.07, and field synergy β diminished from 83.11 to 76.60. Although the pressure loss increased from 2.30 % to 3.50 %, this is within an acceptable range.

Experimental Investigation on Boiling Heat Transfer Characteristics of Liquid Methane in Mini Channel

LOX/LCH4 rocket engine has been recognized as the ideal power choice for future space vehicles due to the merits of low cost, non-toxic and pollution-free, convenient maintenance, suitable for reuse and high specific impulse. In the process of wide range variable thrust of LOX/LCH4 rocket engine, the coolant methane is in a subcritical state due to the low combustor pressure under low operation conditions. The instability of two-phase flow is easy to occur in regenerative cooling channel (RCC), and it is urgent to investigate the heat transfer performance of methane with phase change in RCC. Experiments have been conducted to investigate the flow boiling characteristics of liquid methane in the single mini channels with the diameters of 1.0, 1.5 and 2.0 mm. Effects of the mass flux (266.75~1781.26 kg/m2·s), inlet pressure (0.56~4.24 MPa), heat flux (53.25~800.07 kW/m2) and channel diameter (1.0~2.0 mm) on the flow boiling heat transfer coefficients are tested. Results show that there are two regions with different heat transfer mechanism, one is the nucleate boiling dominated region for low mass quality and the other is the convection evaporation dominated region for high mass quality. A new correlation expressed by Bo, We, Kp, X, Co, Ftg is proposed, which yields good fitting for 355 experimental data with a mean absolute error (MAE) of 10.9%. Present experimental results can provide reference for the thermal protection prediction and optimal design of RCC in LOX/LCH4 rocket engine.

Combustion stability, RGF and pressure referencing effect on HRR for a high compression ratio SI engine with natural gas lean mixtures

The knocking and heat release based on cylinder pressure trace is a widespread practice in combustion diagnostic for conventional SI engines. The accuracy depends on quality of measured in-cylinder pressure, thermodynamic models and parameters feeding such models. In non-conventional engine, common models to assess engine operation, do not satisfy properly expected standard, thus application of new methods and models is required. This study presents the determination of knocking intensity by in-cylinder pressure and cycle-to-cycle variability for operation analysis, the effect of referencing pressure and residual gas fraction on heat release for non-conventional SI engines with high compression ratio with natural gas at partial loads and lean mixture. Higher spark timings was achieved at 21 degrees, limited by low occurrence audible knock for KI20 over 0.04 bar. Compression ratio 15.5, engine speed at 1800 rpm, air-cooled system, and equivalence ratio of 0.73 make limited the operation. KI20 of 0.072 was reached at IMEP 3.96 bar and spark timing of 21 degrees. Maximum CoV of KI20 was 27.1. Pressure referencing shows low differences in polytropic coefficients of 1.34. Slight difference for RGF generates differences in the mass burned up to 12%, and around 0.4 degrees in combustion duration.

Performance and energy balance analysis of the downsized SI engine with using a novel OPCVCR and synchronized twin spark plugs configurations

Recently, the exhaust emissions become one of the main issues in the downsizing spark ignition (SI) engine. It is necessary to develop clean combustion and high efficiency SI engines for further increasing the performance and brake thermal efficiency. In this study, a novel opposite piston type continuous variable compression ratio (OPCVCR) mechanism combined with synchronous twin spark plugs configurations was proposed and applied in the turbocharged downsizing SI engine. The purpose of this study was to propose a novel type of OPCVCR engine and analyze its combustion, performance and energy balance characteristics. The results showed that the peak combustion temperature (PCT) and peak combustion pressure (PCP) of the OPCVCR engine with twin spark plugs were increased when the compression ratio (CR) increased. The knocking combustion intensity of the downsized SI engine was increased when the CR increased, while the knocking combustion intensity can be alleviated effectively by introducing the external EGR. In addition, the energy utilization efficiency was increased with increasing the CR of the OPCVCR engine with twin spark plugs. Besides, the indicated specific fuel consumption (ISFC) of the base downsized SI engine could be decreased by 23.59% and the indicated thermal efficiency (ITE) of the base downsized SI engine could be increased 21.62% by adopting CR 16 and introducing 10% external exhaust gas recirculation (EGR), respectively.

Experimental Study on Combustion Efficiency and Pressure Gain Characteristic of RDC with Guide Vanes

ABSTRACT The influence of guide vanes on the combustion efficiency and pressure gain characteristic of rotating detonation combustor was studied. In this experiment, aviation kerosene (RP-3) was used as fuel and hot air was used as oxidant under the condition of maintaining a certain air flow of 1.5 kg/s. The Temperature rise method was used and the combustion products were analyzed by the flue gas analyzer to calculate the combustion efficiency. Pressure gain characteristic of the rotating detonation combustor was calculated by the mass flow function method (MFFM). The detonation was successfully initiated and operated stably in two rotating detonation combustor configurations without guide vanes and with guide vanes installed. Without the guide vanes, the equivalent ratios for reliable operation of the rotating detonation combustor were relatively small, and the mode of detonation wave propagation is mainly two-counter rotating wave mode. Behind the guide vanes were installed, the range of equivalent ratios for reliable operation of the rotating detonation combustor moved to the appropriate chemical equivalent ratio, and the main mode of detonation wave propagation is two-co rotating wave mode. When the guide vanes were installed, the combustion efficiency of the rotating detonation combustor reached the maximum value of 60.29% when the equivalence ratio is 0.78. In both combustor structures, the pressure gain characteristic increased with the increase of equivalence ratio.

Deprotonation-assisted electrochemical synthesis of copper nitrotriazole with excellent ignition performance

Electrochemical synthesis serves as a green and efficient method with great application potential. However, it has not been extensively applied in the synthesis of energetic materials. Nitrogen-rich heterocyclic compounds, as a new generation of energetic materials, enjoy advantages such as eco-friendliness, high energy output, and excellent safety performance. This study reports the electrochemical cathodic synthesis of copper nitrotriazole [Cu(NTz)2] using copper chloride and 3-nitro-1,2,4-triazole as a reaction substrate and triethylamine as a deprotonation agent. The obtained Cu(NTz)2 comprises uniform spherical particles of nano lamellae. As the dosage of triethylamine increased from 50 μL to 150 μL, Cu(NTz)2 gradually grew into compact solid spherical particles, significantly increasing the energy output. Notably, the heat release increased from 711 J g−1 to 1301 J g−1, accompanied by a significant positive elevation of ignition performance and peak combustion pressure in the process of confined combustion. This greatly boosted the energetic performance of Cu(NTz)2. Moreover, Cu(NTz)2 demonstrates insensitivity to electrostatic discharge (E50＞225 mJ) and friction (FS＞360 N), suggesting excellent safety performance. Owing to its outstanding energetic and safety performance, Cu(NTz)2 boasts great potential for application as pyrotechnic compositions, including military gas-producing and incendiary agents. Moreover, it has been corroborated that Cu(NTz)2 can be applied as a micro ignitor.

Numerical investigation on the effects of fueling the Turbulent Jet Ignition gas engine with methane and hydrogen

The modern solution of two-stage combustion, namely the Turbulent Jet Ignition (TJI), enables the combustion of ultra-lean mixtures. Thanks to this solution, it became possible to reduce fuel consumption and, at the same time, to increase the combustion process indicators (including the overall combustion system efficiency). The article presents the results of numerical tests of a heavy-duty engine equipped with the TJI system running on gas fuels. The AVL BOOST software was used to analyze the effects of different fuel injection rates into the pre-chamber and various ignition timing angles, while maintaining a constant global excess air ratio. Increasing the proportion of hydrogen in the pre-chamber resulted in its reduction in the main chamber (the fuel dose was kept constant with different excess air coefficients in each of the chambers). The maximum combustion pressure values in both chambers were investigated. Changes in the amount of heat released and its release rate were determined. As a result of the simulations, different ignition and combustion conditions were presented for the tested fuels. Based on this, maps of fuel dose to prechamber vs. ignition advance angle were drawn up, showing selected thermodynamic indicators of the combustion process.

Electrostatic Spraying Microspheres of Nano Boron and Its Constant-Volume Combustion with Potassium Nitrate

ABSTRACT The nanometer boron (nB) powders have become the most promising high-energy additive in the field of fuel-rich solid propellants due to their extremely high gravimetric and volumetric calorific value. However, further applications are limited by its disadvantages such as easy agglomeration, easy oxidation, high ignition temperature, and incomplete energy release. Herein, nB powders were pre-agglomerated into microspheres by electrostatic spray method using fluoropolymer (F2602) as binders. The morphology and structure of the samples were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray energy spectrometry (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), and Brunauer-Emmett-Teller (BET). Results showed that the pre-agglomerated nB microspheres had good dispersion, high sphericity, and no surface oxide. The thermal performance and combustion performance of the samples were characterized by a synchronous thermal analyzer and combustion pressure test device. Results showed that the nB microspheres had the highest oxidation weight gain within 1000°C and lowest activation energy compared to the same scale micron boron. In addition, the microspheres significantly shorten the combustion time and improve the combustion efficiency.The pressurization rate of nB microspheres is 4.12 times that of micron boron powders and 2.85 times that of nB powders. These excellent properties may be related to its unique spherical porous structure. Therefore, the preparation of nB microspheres with controllable structure by electrostatic spraying has a good application prospect.

Thermodynamic evaluation of a state-of-art poly-generation system fueled by natural gas and biomass for cooling, power, and hot water generation

The principal objective of this study was to conduct a thorough examination of the thermodynamic aspects of an innovative combined poly-generation facility, encompassing cooling load, hot water, and power generation cycles, powered by a combination of natural gas and biomass. A distinctive feature was the incorporation of syngas into natural gas to enhance overall plant performance. The plant design comprised three key subsystems: a gasification and combustion chamber, a double-effect absorption chiller, and a supercritical carbon dioxide cycle. Energy and exergy analyses were employed to systematically evaluate the thermodynamic behavior of the plant. The outcomes revealed that the exergy and energy efficiencies, along with the net power output, were determined to be approximately 35 %, 78 %, and 7422 kW, respectively. Additionally, the produced hot water and the coefficient of performance (COP) of the absorption chiller were estimated at around 14.71 kg/s and 1.209. Notably, the gasifier and combustion chamber emerged as the least efficient components of the system, primarily due to their elevated rates of exergy destruction. Furthermore, comprehensive parametric investigations were conducted to elucidate the influence of key variables on plant performance. The analysis indicated that variations in gasification temperature positively impacted the thermodynamic performance of the plant. Moreover, an increase in combustion pressure led to a notable enhancement in the net power output of the facility.

Development of a Thermodynamic Model for Supercharged Diesel Engine Performance and Combustion Characteristics Study

ABSTRACT Development of a model that allows performance and combustion characteristics for a supercharged diesel engine was the main objective sought by the present work. Thus, the developed model is used, to examine the impact of start combustion, combustion duration, compression ratio, and heat flux, as well as intake conditions such as pressure and temperature, on the combustion characteristics of the supercharged diesel. For this purpose, a one zone thermodynamic prediction model was adopted with Wiebe function for combustion sub-model. The heat transfer was correlated using Woschni correlation. A numerical simulation is developed considering the crankshaft angle as the independent variable. Validation of the computational code has been favorably evaluated using our experimental data. To give a more general aspect to the developed model, experimental data found in the literature, are also used for this purpose. The results show that the addition of a turbocharger increases low-speed airflow and hence fuel consumption. In addition, an increase in intake pressure contributes to the rise of the heat flux released during combustion, while an increase in intake temperature leads to a strong increase in combustion temperature. Moreover, an increase in the compression ratio leads in a remarkable increase in all parameters simultaneously. However, maximum combustion pressure limits must not be exceeded. This is because the pressure has an effect with the engine mechanical strength.

Energy efficiency analysis and optimization of a pressurized oxy-fuel circulating fluidized bed combustion system

The commercial application of oxy-fuel combustion technology is limited by energy deduction which is caused by addition of air separation unit (ASU) and carbon dioxide compression and purification unit (CPU). Pressurized circulating fluidized bed (CFB) oxy-fuel combustion technology is one option to improve the net electric generation efficiency. In this research, a series of simulations and optimizations were carried out to analyze the energy efficiency of a pressurized oxy-fuel combustion system. The boiler structure and heat exchange surface arrangement under different pressure were calculated. The cross-sectional area of the furnace and tail flue were both reduced up to 10 % of the original size and the floor space of the boiler was considered to be the lowest at 1.1 MPa. The energy efficiency and exergy analysis were used to explore the influence of pressure on the net efficiency and the optimization potential of system. The net electric generation efficiency reached a maximum value of 24.16 % at 1.1 MPa, which is 5.4 % higher than that at atmospheric pressure. Finally, four parameters, i.e. preheat temperature, oxygen concentration, ASU outlet oxygen purity and CPU compressor outlet pressure, were optimized to improve the system net efficiency to 26.67 %, 29.04 %, 25.87 % and 24.36 %, respectively.

Numerical Prediction on In-Cylinder Mixture Formation and Combustion Characteristics for SIDI Engine Fueled with Hydrogen: Effect of Injection Angle and Equivalence Ratio

Although their ease of transport, storage, and use makes hydrocarbon fuels dominant in commercial energy systems, the emission of harmful gases, including greenhouse gases, is a fatal disadvantage. Despite ongoing research to improve thermal efficiency and reduce the emissions of internal combustion engines using conventional hydrocarbon fuels, achieving net-zero carbon requires decarbonizing fuels rather than reducing the use of internal combustion engines. Hence, transitioning away from hydrocarbon fuels and evolving internal combustion engines into clean engines using carbon-free fuels, such as hydrogen, is necessary. This study designs a 2.0 L research engine and numerically analyzes its combustion characteristics and spray behavior by varying the spray angle and equivalence ratio. When comparing the turbulence kinetic energy at a 45-degree spray angle with that at 30 degrees and 60 degrees, on average, there was a difference of approximately 37.54 m2/s2 and 26.21 m2/s2, respectively. However, misfires occur in the lean condition. Although hydrogen has a wide flammability range, poor mixture formation under lean conditions can result in misfires. The 60-degree spray angle resulted in the highest combustion temperatures and pressures for all equivalence ratio conditions, consequently leading to the highest emissions of nitrogen oxides. Specifically, at a lambda value of 2.5, the 60-degree spray angle emitted approximately 29 ppm, 0 ppm, and 161 ppm of nitrogen oxides for each respective spray angle.

Experimental analysis of the effect of hydrogen as the main fuel on the performance and emissions of a modified compression ignition engine with water injection and compression ratio reduction

This study aimed to investigate the combined effects of compression ratio (CR), start of injection angle (SOI) and water injection (WI) on the performance, including NOx emissions, of a modified turbocharged compression ignition engine using H2 as the primary fuel and diesel solely as a pilot ignition source. WI and H2 were both injected into the intake manifold just after the charge heat exchanger. Test conditions varied the engine speed from 1500 rpm to 2750 rpm, covering a wide range of the original engine's operating conditions, water mass flow varied from 0 to 0.795 g/cycle and SOI for pilot ignition was studied in the range 10°, 5°, 0° before top dead center. Subsequently, the study examined the combined effect of reducing the engine's CR from 17.5:1 (base) to 13.5:1, in one-point increments, reducing SOI and water addition to further enhance the hydrogen energy share (HES).HES varied from 0 % to 85 % under different engine conditions, and WI and SOI were employed to prevent knocking and ensure that the maximum combustion pressure did not exceed 160 bar. The test results indicate that NOx emissions increase with HES, but reducing the CR results in a reduction in NOx emissions of approximately 50 %. Additionally, WI further reduces NOx emissions by up to 50 %. The experimental evidence demonstrates that combining WI with CR and SOI reduction can effectively lower NOx emissions, achieving an efficiency greater than 35 % and therefore approaching the base diesel mode's efficiency. This also reduces the maximum in-cylinder pressure, allowing for an increase in turbocharger pressure and consequently enhancing the engine's specific power. The maximum engine power achieved was 31.6 kW at 2500 rpm (mean effective pressure of 10.1 bar), with a CR of 15.5, SOI at 10°, 1.5 kg/kWh of water, a HES of 81 %, and a minimum NOx level of approximately 480 ppm, with a maximum combustion pressure below 120 bar.

Influence of hydrogen fraction and injection timing on in-cylinder combustion and emission characteristics of hydrogen-diesel dual-fuel engine

In order to achieve low-carbon, high-efficient and clean combustion for internal combustion engines, hydrogen-diesel dual-fuel combustion mode (HDDF) was conducted on a 4-cylinder common-rail diesel engine. This research investigated the effects of hydrogen substitution ratio (HSR) and diesel injection timing (DIT) on in-cylinder combustion and emission characteristics of HDDF engine at 20% and 40% loads. The results show that with the increase of HSR, the maximum combustion pressure of HDDF engine shows a decreasing trend, and the peak phase gradually advances. The overall trends of COVIMEP and combustion duration increase. The NO, CO2, CO, Soot and HC emissions all decrease, while NOx emissions first decrease and then increase. At 20% load and HSR = 30% conditions, CO2 emission decreases by 14.96% compared to baseline engine. With the advance of DIT, the maximum combustion pressure of HDDF engine increases, the ignition delay and combustion duration become longer, and COVIMEP shows a downward trend. The NO2, NO, CO2 and NOx emissions and BTE increase, while both CO and HC decrease. When the DIT is advanced from −2 °CA ATDC to −10 °CA ATDC, the BTE of HDDF engine increases from 28.8% to 31.3%.

Propulsion theoretical and experimental analysis of composite propellants motors

Rockets have revolutionized space technology and human space exploration. Most rockets and missiles are both propelled by rocket motors that use composite solid propellants. The ICT code and the NSAS CEA code are two programs that can be used to forecast theoretical propulsion parameters for composite solid rocket propellant. Rocket propellant performance is governed by a specific impulse factor, which is calculated theoretical and experiment. In this paper, the theoretical specific impulse for different composite solid propellant formulations at 70 bar combustion pressure and an adapted nozzle (optimum expansion) were calculated by the NASA-CEA code and the ICT code. Meanwhile, a static firing test was performed on a small scale test motor to experimentally determine the actual specific impulse. The objective is to verify theoretical calculations from two codes with experimental data, via the determination of the specific impulse deviation co-efficient.