Spray Injection Research Articles

Rate of heat release characteristics of supercritical sprays of dieseline blend in constant volume combustion chamber

In present experimental study, combustion characteristics of homogeneous supercritical (SC) fuel spray injection system are analyzed in cylindrical constant volume combustion chamber (CVCC) at experimental conditions similar to diesel engine-like operating conditions. A comparative study is also performed between SC fuel spray and normal diesel spray combustion under similar conditions. Combustion characteristics of SC fuel sprays includes rate of heat release (ROHR) and peak pressure (PP). Operating parameters include hot surface temperature range (673 ​K–723 ​K), pre-firing cylinder air pressure range (20 ​bar–40 ​bar) and injection pressure (IP) range of 100 ​bar–300 ​bar. Piezoresistive pressure transducer is employed for indicating and recording combustion processes. Diesel fuel and dieseline blend (50% gasoline and 50% diesel by v/v) are used for normal diesel spray and SC spray combustion respectively. It is found that ROHR in SC fuel spray combustion is smaller than in normal diesel spray combustion at all operating conditions. In SC fuel spray combustion, ROHR increases with increase in IP but decreases with increase in HST and CP due to homogeneous and hot air combustion nature of SC fuel sprays. Percentage reduction in ROHR of SC fuel spray combustion as compared to ROHR in normal diesel spray combustion is found to be nearly 34% at normal operating conditions of diesel engine. PP reached during SC spray combustion is noted to be less than PP reached during normal diesel spray combustion in all cases and is responsible for reduced NOx formation in SC spray combustion.

Experimental investigations to predict optimistic biodiesel(s) and its optimistic operating conditions by varying ignition delay period and fuel spray pressures for lower emissions and better performance

In this study, different characteristics of sustainable renewable biodiesels (those have a high potential of their production worldwide and in India) were compared with the characteristics of neat diesel to determine optimistic biodiesel for the diesel engine at 250 bar spray pressure. Optimistic fuel gives a comparatively lower level of emissions and better performance than other selected fuels in the study. Rubber seed oil methyl ester was investigated as an optimistic fuel among the other selected fuels such as sunflower oil methyl ester, neem seed oil methyl ester, and neat diesel. To enhance the performance characteristics and to further decrease the level of emission characteristics of fuel ROME, further experiments were conducted at higher spray (injection) pressures of 500 bar, 625 bar, and 750 bar with varying ignition delay period via varying its spray timings such as 8°, 13°, 18°, 23°, 28°, and 33° before top dead center. Spray pressure 250 bar at 23° before top dead center was investigated as an optimistic operating condition where fuel rubber seed oil methyl ester gives negligible hydrocarbon emissions (0.019 g/kW h) while its nitrogen oxide (NOX) emissions were about 70% lesser than those observed with neat diesel, respectively.

ANTITUMOR EFFECTS OF MESENCHYMAL STEM CELLS

The problem of treatment of oncologic patients is not resolved. Our experiments focused on the ability of autologous mesenchymal stem cells (MSCs) to inhibit glioma cell growth in vitro and in vivo. 28 thousand cells of C6 glioma in 20 μl of culture medium were stereotactically introduced into occipital region of brain (Oc2L) from the right side after craniotomy in experiments on 30 male Wistar rats weighing 250–270 g under ketamine‐xylazine‐acepromazine (55.6, 5.5, and 1.1 mg/kg, respectively) anesthesia. 20 rats received 400 thousand MSCs labeled with CD90s and FITC in 50 μl of culture medium under nasal mucosa during the operation. Brain slices 8 μm in thickness were prepared after decapitation of one rat from each group in one day after surgery. MSCs distribution was visualized using Zeiss AxioVert 200M fluorescence microscope with Zeiss AxioCam HRm CCD camera. Fluorescent MSCs were revealed only in damaged Oc2L area of the rat with previously injected MSCs. 10 rats from the same group (with preimplanted MSCs) received 400 thousand MSCs in 50 μl of culture medium via weekly spray injections into both nasal cavities. Rats with implanted glioma and without MSCs died in 15.0±4.3 days. Rats with implanted glioma and single intranasal MSCs injection died in 21.1±5.2 days. 8 of 10 rats that received both intranasal MSCs injection and subsequent weekly spray MSCs injections died in 33.6±3.4 days. Two rats are still alive (108 days from the date of operation). Morphological examination of brain slices of rat from the last group showed signs of apoptosis of tumor cells. It was assumed that MSCs trigger apoptosis in C6 glioma cells via paracrine way by excretion of exosomes and cytokines.

Improving RNAi efficiency for pest control in crop species.

The application of RNAi promotes the development of novel approaches toward plant protection in a sustainable way. Genetically modified crops expressing dsRNA have been developed as commercial products with great potential in insect pest management. Alternatively, some nontransformative approaches, including foliar spray, irrigation and trunk injection, are favorable in actual utilization. In this review, we summarize the recent progress and successful cases of RNAi-based pest management strategy, explore essential implications and possibilities to improve RNAi efficiency by delivery of dsRNA through transformative and nontransformative approaches, and highlight the remaining challenges and important issues related to the application of this technology.

Leidenfrost behavior in drop-wall impacts at combustor-relevant ambient pressures

Liquid-fueled combustion systems demand optimal performance over a range of operating conditions—requiring predictable fuel injection events, spray breakup, and vaporization across a range of temperatures and pressures. In direct injection combustors, these sprays impinge directly on combustion chamber surfaces. Although the outcome of fuel droplets impacting a wall is primarily driven by the wall temperature and the Leidenfrost effect, the shifting liquid-vapor saturation point with pressure may influence the droplet-wall heat transfer rate and transition from nucleate to film boiling. In this paper, the role of ambient pressure on the droplet impact regimes, spreading rate, and droplet rebound velocity during impact are explored for representative low boiling point and high boiling point pure hydrocarbon liquids (n-heptane and n-decane). High-speed image sequences of the drop-wall impact were acquired for ambient pressures of 1–20 bar and wall temperatures ranging from 35–300 ∘C with a drop Weber number of ~ 50. Droplet impact sequences were recorded using a high-speed CMOS camera and were processed to measure the droplet spread, droplet rebound velocity and track the droplet centroid motion. The dynamics of the drop spreading and rebound show similar behavior across a range of ambient pressures with the largest differences observed for wetted versus non-wetted cases (above the Leidenfrost temperature). For both fluids, the onset of drop rebound remains bounded by the saturation temperature (shifting with ambient pressure) and the thermodynamic limit of liquid superheat. This leads to a decrease in the superheat temperature above the saturation point as the critical pressure is approached.

Simulation Study on the Impact of Uneven Fuel Injection of Each Hole of the Diesel Engine Injector on the Combustion Process

The spray impulse and injection pressure of each hole of the 4-hole injector of F186 engine were tested by using the transient test system for flow coefficient and injection rate of each hole of the injector, and the injection rate, fuel injection quantity and flow coefficient of each hole were obtained. According to the measured injection rate of each hole and cycle fuel injection quantity, a 3D model of the diesel engine was established with the FIRE software, and the uniform injection rate and uneven injection rate of each hole were made as the injection setting for the combustion simulation to comparatively analyze the influence of the uneven injection rate of each hole on the combustion process of diesel engine. As the injection of each hole is uneven, some holes with high injection rate have long fuel spray penetration distance and the fuel spray is fully mixed with the air, and the ignition starting point is moved ahead. When compared with the case of uniform injection rate, the phase corresponding to the heat release rate in the case of uneven injection rate is moved forwards, the maximum cylinder pressure and temperature rise fast, the maximum cylinder pressure and maximum average temperature in cylinder are higher, the NO generation is larger, and the Soot generation is slightly larger. In the case of uneven injection rate from four holes, as the utilization of air in the hole-located cylinder space by the fuel spray is uneven, the hole with a large quantity of injection makes the oxygen in the hole-located cylinder space relatively low, the wall collision of the hole with high injection rate is more, and the diffusion combustion is incomplete and insufficient.

How Have the Views on Myofascial Pain and its Treatment Evolved in the Past 20 Years? From Spray and Stretch and Injections to Pain Science, Dry Needling and Fascial Treatments

How Have the Views on Myofascial Pain and its Treatment Evolved in the Past 20 Years? From Spray and Stretch and Injections to Pain Science, Dry Needling and Fascial Treatments

Large-eddy simulation of dual-fuel spray ignition at different ambient temperatures

Here, a finite-rate chemistry large-eddy simulation (LES) solver is utilized to investigate dual-fuel (DF) ignition process of n-dodecane spray injection into a methane–air mixture at engine-relevant ambient temperatures. The investigated configurations correspond to single-fuel (SF) ϕCH4= 0 and DF ϕCH4= 0.5 conditions for a range of temperatures. The simulation setup is a continuation of the work by Kahila et al. (2019, Combustion and Flame) with the baseline SF spray setup corresponding to the Engine Combustion Network (ECN) Spray A configuration. First, ignition is investigated at different ambient temperatures in 0D and 1D studies in order to isolate the effect of chemistry and chemical mechanism selection to ignition delay time (IDT). Second, 3D LES of SF and DF sprays at three different ambient temperatures is carried out. Third, a reaction sensitivity analysis is performed to investigate the effect of ambient temperature on the most sensitive reactions. The main findings of the paper are as follows: (1) DF ignition characteristics depend on the choice of chemical mechanism, particularly at lower temperatures. (2) Addition of methane to the ambient mixture delays ignition, and this effect is the strongest at lower temperatures. (3) While the inhibiting effect of methane on low- and high-temperature IDT’s is evident, the time difference between these two stages is shown to be only slightly dependent on temperature. (4) Reaction sensitivity analysis indicates that reactions related to methane oxidation are more pronounced at lower temperatures. The provided quantitative results indicate the strong ambient temperature sensitivity of the DF ignition process.

Effect of Double Injector on Combustion Process in a 396 Series Diesel Engine

The 396 series diesel engine has high performance, reliability and long service life, which has been widely used in many fields including ship, vehicle and industrial power unit. With the improved injection system and dual-injector in each cylinder, two injectors of the diesel can spray diesel at the same time; or one injector sprays ignition diesel and the other injector sprays biodiesel or alcohol fuel. A 3D combustion model of the 396 series diesel engine with flat-top convex basin combustion chamber is established by using the computational fluid dynamics software FIRE, and the combustion process when uniform 5-hole and 8-hole injectors and 4-hole dual-injector are adopted is simulated to compare and analyze the fuel spray, ignition start point, combustion pressure, combustion heat release rate, average temperature in cylinder and NO emission. Compared with the diesel engine adopting 8-hole injector, the diesel engine adopting 4-hole dual-injector has a wide spray space distribution area, high pressure and temperature in cylinder, and high thermal efficiency. The combustion process with injection duration of 26.84°CA, 22°CA and 20°CA for 396 series diesel engine adopting 4-hole dual-injector is simulated respectively, and the simulation result shows that the shorter injection duration can bring the higher maximum pressure and the maximum average temperature in cylinder, the shorter ignition delay period, the advanced ignition start point, the larger peak value of combustion heat release rate, the more concentrated combustion heat release, the higher NO emission. These three cases have almost the same accumulated heat release and the relatively complete fuel utilization. The proper injection duration shall be selected based on comprehensive consideration of the pressure in cylinder, effective power and NO emission. This research result is conductive to improve the combustion process of the 396 series diesel engine with the dual-injector and provides a basis for using biodiesel and alcohol fuel in the diesel engine.

Effects of injection strategy and combustion chamber modification on a single-cylinder diesel engine

The diesel engine is widely used due to its thermal efficiency, reliability and fuel economy, while diesel engine emissions are harmful to the environment and human health. Therefore, the standards (EPA, Tier, NRE-v/c standards, etc.) limit the exhaust emission of engines around the world. The most successful method of reducing emissions is to optimize the combustion chamber and the fluid motion inside the engine. In this study, experimental and numerical methods were used in a diesel engine to analyze fluid motion, spray, combustion process, and exhaust emissions. A new type of swirl piston bowls and a reentrant piston bowl were utilized on a baseline diesel engine. Different spray angles and injection pressures were applied and results were compared with the baseline design. Results show that the piston bowl shape has a critical influence on engine performance and emissions. Since the multi-swirl piston bowl (MSB) and double-swirl piston bowl (DSB) design increases in-cylinder swirl and turbulence, it contributes to reducing emissions and improving the combustion process. Increasing spray angle and injection pressure and using of DSB can reduce the soot emissions by 81%. DSB and MSB improve the combustion process but also increase NOX emissions due to increased in-cylinder temperature. On the other hand, NOX emissions may also be reduced if the injection parameters of the engine are optimized to provide the same power with the new swirl bowls.

Characterization of fuel/water mixtures and emulsions with ethanol using laser-induced fluorescence.

In charged spark-ignition engines, additional water injection allows for the reduction of temperature under stoichiometric mixture conditions. However, a higher complexity of the injection and combustion processes is introduced when a mixture of fuel and water ("emulsion") is injected directly into the combustion chamber using the same injector. For this purpose, the mixture must be homogenized before injection so that a reproducible composition can be adjusted. In principle, gasoline and water are not miscible, and may form an unstable macro-emulsion during mixing. However, the addition of ethanol, which is a biofuel component that is admixed to gasoline, can improve the mixing and may lead to a stable micro-emulsion. For the assessment of the distribution of the water and fuel phases in the mixture, a novel imaging concept based on laser-induced fluorescence (LIF) is proposed. In a first spectroscopic study, a fluorescence dye for imaging of the water phase is selected and evaluated. The fluorescence spectra of the dye dissolved in pure water are investigated under varied conditions using a simplified pressure cell equipped with a stirrer. The study comprises effects of temperature, dye concentration, and photo-dissociation on fluorescence signals. In a second step, fuel is mixed with water (5 vol. % to 10 vol. %) containing the dye, and the water dispersion in the fuel is investigated in an imaging study. Additionally, the miscibility of fuel and water is studied for varying ethanol content, and the homogeneity of the mixture is determined. These first investigations are also essential for the assessment of the potential of the LIF technique for studying the distribution of the water phase in internal combustion engine injection systems and sprays.

筒内直接噴射水素エンジンの水素噴流と噴射時期の最適化による高熱効率・低NOx ニアゼロエミッションの実現と一層の性能向上に関する研究

筒内直接噴射水素エンジンの水素噴流と噴射時期の最適化による高熱効率・低NOx ニアゼロエミッションの実現と一層の性能向上に関する研究

Research and Development of Gasoline Direct Injection Image Acquisition System

Both industry standards and international standards in the field of automobiles recommend the image test method to detect the spray performance of the fuel injector. It is necessary to accurately determine the time when the fuel injector starts spraying and capture the spray image at the standard time for analysis. An injector spray image acquisition system based on photoelectric detection technology is proposed. The infrared photoelectric sensor is used to determine the initial starting time of the injector. The FPGA chip receives the trigger signal of the photoelectric sensor and then sends driving pulses to the industrial camera in the external trigger acquisition mode to realize spray image acquisition. Then, it is transmitted to the upper computer through gigabit network interface for subsequent image processing. The experimental results show that the system has stable performance and high quality of collected images, fully meets the high precision requirements of spray detection, and can be extended to droplet velocity measurement and other fields.

Intrapolyp Corticosteroid Injection versus Oral Corticosteroid versus Topical Nasal Corticosteroid Spray in Treatment of Allergic Nasal Polyposis: Comparative Study

Background: Nasal Polyposis are treated with topical steroids, systemic oral steroids, surgical excision, and intrapolyp steroid injection. Local and systemic steroid treatment is the mainstay of therapy for nasal polyposis. Objectives: The aim of this study was to evaluate the role of intrapolyp steroid injection in the treatment of nasal polyposis and its efficiency, and to compare these results with that of oral and topical nasal spray corticosteroid. Patients and Methods: This study involved 60 patients presented at ENT Outpatient Clinic, Al-Zahraa University Hospital and diagnosed as nasal polyposis. Their age ranged between (18-60) years. They were randomly divided according to type of treatment (nasal corticosteroid spray, oral corticosteroid and intranasal injection of corticosteroid) into 3 groups, each consisted of 20 patients. Results: There were statistically significant differences in total nasal symptom score (TNSS), nasal polyp score (TNPS) and endoscopic analysis. It has been noted that in nasal spray group, Improvement of symptoms with No Regression of Polypis observed in 13 patients (65%) and no change at all in 7 patients (35%). While in oral steroids group, complete regression is observed in 4 patients (20%), partial improvement in 11 patients (55 %), and no response in 5 patients (25%) and in injection group, complete regression of polyps is observed in 2 patients (10%), partial improvement in 13 patients (65%), and no change at all in 5 patients (25%). Conclusion: It could be concluded that intrapolyp steroid injection could be considered one of the alternative treatments of sinonasal polyposis as it is effective, easy, and safe procedure and its effect lasts for at least 3 months.

Combustion and soot formation characteristics of homogeneous supercritical sprays of dieseline blend in constant volume chamber

In present work, combustion and soot formation characteristics of supercritical (SC) sprays are studied in a cylindrical constant volume combustion chamber under diesel engine-like experimental conditions. Hot surface temperature range (673 K to 723 K), initial cylinder pressure range (2 MPa to 4 MPa) and injection pressure range of 10 MPa to 30 MPa are the experimental conditions. Photo sensor and piezoelectric sensors are employed for indicating combustion and injection events respectively. Commercial diesel fuel and dieseline blend are employed for analyzing combustion of normal diesel and SC sprays respectively. It is investigated that duration of combustion of SC sprays are substantially lower than normal diesel sprays at all experimental conditions. Percentage reduction in DOC of SC sprays as compared to diesel sprays is above 35% for all cases. Percentage reduction in DOC of SC sprays is observed highest at higher IP of 30 MPa. Percentage reduction in soot formation (SF) in SC spray combustion is more than 90% at all operating conditions. At normal diesel engine operating conditions, nearly 82% reduction in DOC and about 96% reduction in SF are found. Combustion of SC sprays seems hot air and single-phase homogeneous combustion unlike that of normal diesel sprays having hot surface ignition/combustion. SC spray injection system proves out to be a faster as well as cleaner combustion technology for future high speed direct-injection engines.

Experimental Analysis of Gasoline Direct Injection Spray Characteristics by Mixing with High-boiling Component Fuel

Experimental Analysis of Gasoline Direct Injection Spray Characteristics by Mixing with High-boiling Component Fuel

Elucidation of Gasoline Direct Injection Spray Characteristics by Mixing with High-boiling Component Fuel (First Report)

Elucidation of Gasoline Direct Injection Spray Characteristics by Mixing with High-boiling Component Fuel (First Report)

高沸点成分燃料の混合による直噴ガソリン噴霧特性の評価（第2報）:―燃料噴射差圧が噴霧の微粒化特性に及ぼす影響の解明―

高沸点成分燃料の混合による直噴ガソリン噴霧特性の評価（第2報）:―燃料噴射差圧が噴霧の微粒化特性に及ぼす影響の解明―

High Amplitude Combustion Instabilities in an Annular Combustor Inducing Pressure Field Deformation and Flame Blow Off

Abstract This article reports experiments carried out in the laboratory scale annular combustor MICCA-spray equipped with multiple swirling spray injectors. The experimental setup consists in an air plenum connected to a combustion chamber formed by two concentric cylindrical quartz tubes, allowing full optical access to the flames. A new injection system is introduced and characterized. For a wide range of operating conditions, strong combustion instabilities are observed, but the focus of this article is placed on very high amplitude combustion instabilities coupled by a standing azimuthal mode. New results are obtained using a higher order reconstruction method for the pressure field: its shape is shown to be modified during high amplitude oscillation, leading to asymmetries of the pressure distribution in the system. Flame blow off occurs near the pressure nodal line when a critical level of oscillation is reached. A method is proposed to reconstruct the acoustic velocity field just before blow off occurs and in this way determine the blow off threshold. It is found that the pressure distribution, velocity field, and blow off pattern become asymmetric as the amplitude of oscillation increases and that this process is accompanied by a rapid shift in frequency of oscillation. Another notable result is that the heat release rate in the flames on the same side of the nodal line is not perfectly in phase and that the phase differences become larger as the amplitude of oscillation increases.

Experimental investigation of water spray injection in liquid piston for near-isothermal compression

Near-isothermal compression is desired to achieve high efficiency in many compressor applications. Low heat transfer characteristic of conventional compressors is a major bottleneck in attaining a near-isothermal compression. A high heat transfer rate is possible with an injection of a large number of water droplets using a spray nozzle inside the compression chamber. In this paper, the effectiveness of spray injection to achieve near-isothermal compression is investigated experimentally in a liquid piston compressor for a compression ratio of about 2.5. Parametric investigations are performed by varying injection pressures of spray from 10 psi (69 kPa) to 70 psi (483 kPa), using different spray nozzle angles (60°, 90°, and 120°), and by changing the stroke time of compression. It is observed that water spray injection is highly effective in abating the air temperature rise during the compression process. The pressure-volume plots indicate a significant reduction in the compression work, and they approach near-isothermal compression with spray at higher injection pressures. The isothermal efficiency of compression consistently increases with an increased injection pressure of spray and reaches up to 95% at the highest injection pressure studied (70 psi). Furthermore, the spray nozzle angle marginally affected the isothermal efficiency with a 1–4% improvement with the use of a 60° nozzle angle over a 120° spray angle at all injection pressures. Also, comparable isothermal efficiencies are observed for compression with different stroke times between 3 and 5 s especially at higher injection pressures which highlight the efficacy of spray injection in attaining a high power-density along with high efficiency. Overall, with an optimized spray design, water spray injection can achieve a highly efficient near-isothermal compression in liquid piston.