Swirl Injector Research Articles

An Analysis of Swirl Injector Spray Properties under High Injection Pressure Using the PIV Method

The flow velocity fields of swirl injector sprays for direct-injection gasoline engines were measured by using the PIV method. This method made it possible to measure not only transient and complicated spray droplet velocities but also the surrounding air velocity caused by spray formation and to analyze the mechanism of spray formation. In this study, two nozzles with different spray angles were used to analyze the effects of injection pressure and ambient pressure on spray properties and the results made clear the mechanism of spray formation. It was observed in particular that under a condition of high injection pressure (20 Mpa) with high ambient pressure, spray penetration after the injection period was longer than that obtained under low injection pressure (10 Mpa). This is attributed to both the higher spray velocity and the greater surrounding air velocity.

1903 PIV によるスワールインジェクタのノズル近傍噴霧流動解析

1903 PIV によるスワールインジェクタのノズル近傍噴霧流動解析

Development and Application of Flow Rate Meter Based on a Laser Doppler Anemometer.

An LDA flow rate meter which is based on the LDA (Laser Doppler anemometer) technique has been developed. The principle of the LDA flow rate meter applied for circular pipe is following. The center line velocity of pulsating pipe flow was measured by the LDA. The velocity distribution profile in the pipe cross section can be numerically estimated, and then the instantaneous flow rate was calculated by the integration of the profile. Firstly, it was applied and evaluated at the pulsating flow made by an artificial heat-lung system. The system has a double roller pump with a vinyl tube of Ω-shape. Secondly, an intermittent flow rate at high fuel pressure injection system was also measured. Swirl injector generated the oscillating pipe flow under high line pressure of 5 MPa at injection frequencies of 20 and 40 Hz. There was a little difficulty at the measurement of injection flow depending on the zero velocity shifting. Finally, a correction method of zero shifting was proposed and the applicability of the flow rate meter was demonstrated.

Experimental study on axial stratification process and its effects (I)-Stratification in Engine-

This paper is the first of several companion papers, which investigate axial stratification process and its effects in an SI engine. The axial stratification is very sophisticate phenomenon, which results from combination of fuel injection, port and in-cylinder flow and mixing. Because of the inherent unsteady condition in the reciprocating engine, it is impossible to understand the mechanism through the analytical method. In this paper, the ports were characterized by swirl and tumble number in steady flow bench test. After this, lean misfire limit of the engines, which had different port characteristic, were investigated as a function of swirl ratio and injection timing for confirming the existence of stratification. In addition, gas fuel was used for verifying whether this phenomenon depends on bulk air motion of cylinder or on evaporation of fuel. High-speed gas sampling and analysis was also performed to estimate stratification charging effect. The results show that the AFR at the spark plug and LML are very closely related and the AFR is the results of bulk air motion.

Numerical simulation of the reactive two-phase flow in a kerosene/air tubular combustor

Numerical simulation plays today an important role in the design of gas turbine combustors. It requires the understanding of basic physical phenomena encountered in turbulent and reactive flows. In most industrial applications concerning airbreathing propulsion, the fuel is injected in the liquid phase which often consists of a spray of fine droplets. This paper presents numerical simulations of the flowfield, inside a realistic tubular-type combustion chamber geometry, taking into account the interaction between the liquid droplets and the gaseous phase. The in-house ONERA's numerical code MSD was used to compute the turbulent reactive two-phase flow inside this 3D flame tube. In order to promote the liquid spray dispersion in the flow, the kerosene/air mixture is injected through a swirling injection system. A Lagrangian approach has been implemented in order to describe with good accuracy the droplet behaviour. This Lagrangian approach is numerically coupled with the Eulerian formulation describing the gaseous flow. Droplet dispersion induced by the turbulence of the flow is governed by probabilistic models taking into account the local turbulence conditions controlled by a two-equation k– ε model. Results are presented showing the influence of the prescribed swirl intensity on the global flow features. This investigation eventually helped us in finding the most appropriate conditions for future experimental testings.

Design and development of a new gasoline direct swirl injector

Numerical and experimental analyses were carried out to design and develop the optimum geometry of a gasoline direct swirl injector. In the numerical analysis, the needle cone angle, swirler inclined angle and needle lift were changed with mass flowrate as design parameters to determine the optimum sizes. The critical sizes of the needle cone angle, swirler inclined angle and needle lift are 140°, 120° and 100 μm respectively. Thus, the optimum sizes may be 130°, 110° and 80 °m respectively. Experiments were performed to observe spray phenomena and to measure the dynamic flowrate, penetration of the spray tip and mainstream, spray angle and the mean drop diameter using an image processing method. The formation of a counter-rotating vortex appears in the steady state as a feature of the high pressure swirl injector spray. The calculated needle cone and swirl inclined angles as well as the cone-type needle reduce the non-swirl and sac volumes of the non-swirl region such that the reduced volumes restrict the penetration of the spray tip. The sizes of the mean drop diameter range from 20μm to 23μm and the spray angles range from 64° to 66°, which satisfy the requirements of a gasoline direct injection engine.

Three phase cavitating flows in high-pressure swirl injectors

The internal combustion engine remains to be one of the most important sources of energy. The direct gasoline injection (DGI) is a new technology that promises considerable improvement of internal combustion engine efficiency. The key component in the DGI engine is its injection system. A three-phase flow simulation of the flow in the high-pressure swirl injector, typical for DGI engines, is presented here. The model is based on the multiphase extension of the two-fluid model. The most important characteristics of the flow were predicted. The results show the formation of a thin conical fuel sheet with an air core. Cavitation was also predicted in the pressure depression initiated in the air core. The presented approach seems to be very promising for the simulation of flows in DGI injectors.

Spray analysis of a gasoline direct injector by means of two-phase PIV

The hollow-cone spray of a high-pressure swirl injector for a direct-injection spark-ignition (DISI) engine was investigated inside a pressure vessel by means of particle image velocimetry (PIV). As the interaction between the spray droplets and the ambient air is of particular interest for the mixture preparation process, two-phase PIV techniques were applied. To allow phase discrimination, fluorescent seeding particles were used to trace the gas phase. Because of the periodicity of piston engine injection, a statistical evaluation of ensemble-averaged fields to reduce cycle-to-cycle variations and to provide more general information about the two-phase flow was performed. Besides the general spray/air interaction process the investigation of the spray collapse at elevated ambient pressures was the main focus of the study. Future investigations of transient interaction processes require simultaneous techniques in combination with a high-speed camera to resolve the transient interaction phenomena. Therefore, optical filters that attenuate Mie-scattered light and transmit fluorescent light were used to collect both phases on the same image. Consequently, phase separation techniques were employed for data analysis. A masking and a peak separation technique are described and a comparison between the results of an instantaneous two-phase flow field in the spray cone of a DISI injector is presented in the paper.

Solid-Fuel Regression Rate Behavior of Vortex Hybrid Rocket Engines

Aseriesofstaticenginee ringswereconductedtoinvestigatethesolid-fuelregressionratebehaviorandoperating characteristicsofvortexhybridrocketengines.Thevortexhybridenginecone gurationischaracterizedbyacoaxial, coswirling, countere owing vortex combustion e eld in a cylindrical fuel port. To generate this e owe eld, oxidizer is injected through a swirl injector located between the aft end of the fuel grain and the inlet to the converging portion of the exit nozzle. Test e rings with thrusts up to 960 N were conducted with gaseous oxygen and hydroxylterminated polybutadiene solid fuel. Average fuel regression rates up to seven times larger than those in similar classical hybrids were measured. Empirical correlations were developed to describe accurately the experimental regression rates over more than an order of magnitude variation in mass e ux. In addition to local mass e ux and oxygeninjectionvelocity,geometricenginevariables,suchasenginecontractionratioand length-to-diameterratio, had a signie cant ine uence on the measured regression rates. Nondimensional regression rate and heat transfer correlations were also developed. Throttling and restart capability were demonstrated. Nomenclature A = cross-sectional area, cm 2 B = blowing parameter cp = isobaric specie c heat, J/kg ¢K D = port diameter, cm Ea = activation energy, kcal/mole G = local mass e ux, kg/m 2 ¢s Ginj = injection mass velocity, kg/m 2 ¢s GO = gaseous oxygen mass e ux, kg/m 2 ¢s

E211 高温燃料噴霧が直噴エンジン筒内混合気分布形成過程に及ぼす影響

Swirl injector spray at high fuel temperature has unipue characteristics compare with fuel temperature spray such as the strong penetration and narrow spray width. These characteristics have a possibility for improvement of fuel consumption and exhaust emission at cold start condition. Thus, Swirl injector spray at high fuel temperature condition by using multi components fuel evaporation was modeled in a CFD code to predict mixture formation process at cold engine start condition. As the results, high temperature fuel decreases wall film amount and increases vapor amount. It is concluded that high temperature fuel has a possibility for improvement of fuel consumption and exhaust emission at cold start condition.

1722 直噴ガソリン機関の性能と排気に及ぼすスワール噴射弁特性の影響

1722 直噴ガソリン機関の性能と排気に及ぼすスワール噴射弁特性の影響

Fuel and Lubricant. Swirl Injection Lubrication Low Cylinder Oil Consumption without Sacrificing Wear Rates.

Fuel and Lubricant. Swirl Injection Lubrication Low Cylinder Oil Consumption without Sacrificing Wear Rates.

燃料潤滑 新しいシリンダ注油方法

Two types of improved new cylinder lubrication systems, Alpha lubrication and SIP lubrication, are intro-duced.According to the author's simulation results, conventional lubricating system supplies oil mainly under the piston rings and the oil is easily wiped down by the rings. Alpha lubricator supplies the oil mainly between piston rings and oil is retained during more strokes than conventional lubrication. Tests on actual engines with Alpha lubricator proved reduction capability of oil consumption without deteriorating cylinder condition.SIP (Swirl Injection Principle) lubricator sprays the oil onto periphery of upper cylinder liner and forms thin spread oil film. The tests on board proved reduction capability of oil consumption with excellent wear results. This special edition also carries an article on SIP lubrication.

Mixing Characteristics of Coaxial Injectors at High Gas/Liquid Momentum Ratios

A study of the spray of a swirl coaxial gas-liquid injector operating at high gas to liquid momentum ratios is reported. Mixing and droplet size characteristics of the swirl injector are also compared to a shear coaxial injector, currently being used in the Space Shuttle Main Engine fuel preburner. The injectors were tested at elevated chamber pressures using water as a LOX simulant and nitrogen and helium as gaseous hydrogen simulants. The elevated chamber pressure allowed for matching of several of the preburner injector conditions including; gas to liquid momentum ratio, density ratio and Mach number. Diagnostic techniques used to characterize the spray included; strobe back-light imaging, laser sheet spray imaging, mechanical patternation, and a phase Doppler interferometry. Results thus far indicate that the radial spreading of the swirl coaxial spray is much less than was reported in previous studies of swirl injectors operating at atmospheric back-pressure. The swirl coaxial spray does, however, exhibit a smaller overall droplet size which may be interpreted as an increase in local mixing.

Investigation on the Drop Size Distribution of SpraysProduced by a High-Pressure Swirl Injector. Measurementsand Application of the Maximum Entropy Formalism

This paper reports an investigation on the volume-based drop size distribution of sprays produced by swirl atomizers dedicated to direct-injection spark-ignited engines. Because of the use of high injection pressures to reduce the atomization time, the spatial density of the spray is high and prevents from classical measurements of spray drop size distribution. This problem is overcome by combining an experimental approach to the application of the maximum entropy formalism (M.E.F.). Based on the determination of correction factor series to correct the measurements from multiple light scattering, the experimental procedure allows obtaining some distribution characteristic features. According to a previous study, two of these characteristics are used as information in a M.E.F. procedure to derive the spray volume-based drop size distribution. This characteristic is of paramount importance for evaluating the large drop population with accuracy. The overall procedure is presented in detail and discussed. It was applied to a series of four swirl atomizers in order to study the influence of the nozzle geometry and of the injection pressure on the injector performances. Conducted under both stationary and transient working conditions, this study allows a more precise understanding of the performances of GDI injectors as far as the spray drop size distributions are concerned.

(3-11) Techniques for Analyzing Swirl Injectors of Direct-injection Gasoline Engines and Its Application((FS-1)Fuel Sprays 1-Gasoline sprays)

This paper describes the numerical and experimental approaches that were applied to study swirl injectors that are widely used in direct-injection gasoline engines. As the numerical approach, the fuel and air flow inside an injector was first analyzed by using a two-phase flow analysis method employing a volume of fluid (VOF) model. The calculated results made clear the process from initial spray formation to liquid film formation. Spray droplet formation was then analyzed with a discrete droplet model (DDM). As the experimental approach, particle image velocimetry (PIV) was used to measure the spray velocity distribution. These approaches were applied to test nozzles having a tapered tip geometry at the nozzle exit (Fig. I). The spray shapes that are come out from the nozzles skewed to tapered side (Side A). And the cone angle of skewed side spray does not change not so much even under high ambient pressure conditions (Fig. II). Because of this reason since the tapered nozzle is able to make fuel mixture reach towards the spark plugs on the stratified engine condition, i.e. compression condition, we consider this nozzle as the effective tool. At first, internal flow analysis of the nozzles by using VOF model was done, and the results show that the cone angle at the skewed side is larger than that of non-skewed side (Fig. III). After that, Velocity distribution during injection were measured by using PIV (Fig. IV). And the results show that as it apart from the nozzle exit, skewed spray velocity decline much slower than non-skewed spray velocity does. This phenomena are caused mainly by the reason that the quantity of the fuel of the skewed side (Side A) is larger than that of the iron-skewed side (Side B). Spray calculation was done setting this circumferential fuel distribution as initial conditions, the results show on Fig. II, The calculated results show good agreement with the experimental results. These results above show that the spray shapes are influenced mainly by spray cone angle and circumferential fuel mass distribution at the nozzle exit.

Rapid sulfuric-acid absorbers

fuming sulfuric-acid absorption of SO3; monohydrate absorption of SO3 in the first and second stages; and desorption of SO2 from the product sulfuric acid. The following characteristic features must be considered in building apparatus for these processes: • the mass-transfer rate is determined primarily by diffusion and thermal processes in the gaseous phase, and the H2O and SO3 vapors above the acid possess low tension; • the reactions that take place are distinguished by high thermal effects; • accompanying processes occur during formation of the sulfuric-acid fog; • the working environments are toxic ecologically dangerous liquid and gaseous media; • high corrosion activity of the production media with respect to basic metallic structural materials; and • the production rate can be achieved with a small number of degrees of contact (up to five). Counterflow packed absorbers (towers) with nonmetallic (ceramic, porcelain) contact elements (Rashig rings, Intalocks seats, etc.), or direct-flow Venturi-tube apparatus are traditionally used for the execution of these processes. These apparatuses do not, however, correspond to the modern level of mass-exchange equipment. Their use in heavy-duty sulfuric-acid systems is inexpedient due to cumbersomeness and large material outlays. A new generation of sulfuric-acid absorbers, which are distinguished by high rates, compactness, and low material consumption, has been developed. Moreover, energy expenditures have not been increased. The apparatus include tubular and hollow sections. The tubular sections can be oriented horizontally and vertically. The gas in the tubes moves at a velocity of 5–30 m/sec. The liquid is delivered in the form of a spray via injectors in the gaseous flow directly ahead of the inlet to the working tubes. The hollows sections may be operated in a counterflow, direct-flow, or crossing regime at gas velocities of 2–10 m/sec. Alternation of hollow and tubular sections can provide for a high degree of component absorption with a moderate pressure loss. Intensification of the process is achieved in a combined apparatus as a result of the formation of a fresh phase-contact surface as the flows proceed from one section to another (from a hollow to a tubular section, and conversely). Let us consider examples of individual solutions of combined apparatus for specific operating conditions. 1. Fuming sulfuric-acid absorber – a vertical cylindrical vessel with a flat bottom and conical cover. The gas moves along a spiral path and exits via all-jet swirl injectors mounted in the cover of the vessel. The initial gas concentration is 8% of SO3. The degree of SO3 absorption by fuming sulfuric acid (22–25%) amounts to 80–90%, and the loss of gas pressure is 300 Pa. The dwell time of the gas in the vessel is 2.5–3.5 sec. The material outlays and volume of the vessel are three to five times lower as compared with traditional packed vessels. Chemical and Petroleum Engineering, Vol. 37, Nos. 7–8, 2001

K-1922 TABモデルを用いたスワールインジェクタ噴霧のモデル化(S24-3 燃料噴霧(2))(S24 燃料噴霧,ガス流動,混合気形成過程)

Various spray models were investigated to explain fuel spray formation and fuel mixing processes in DI engines. Based on TAB model, spray formation of the swirl injector that is currently used in conventional gasoline DI engines was modeled to an agreement with experimental results. As the results, the structure and the behavior of calculated swirl spray well agree with experimental results at different ambient conditions.

Development of Gasoline Direct Swirl Injector

The Gasoline Direct Injection(GDI) system has been highlighted due to the improvement of fuel consumption and the control of exhaust emission from gasoline engines. The GDI system includes a high injection pressure, smaller mean diameter, good spray characteristics and stability. We were interested in the development for gasoline direct swirl injector(GDSI) in which the swirler is specially designed with an incident angle. Nymerical analysis was utilized to investigate the internal flow of GDSI with a goal to determine the swirl incident angle and needle lift. Accordingly, it describes characteristics of a GDSI in which the flowrate and spray characteristics are satisfied. especially the spray tip penetration decreases, compared with other type GDI, mean diameter of droplets is from 20 to 25 and spray angle ranges from 64to 66.

Development behavior of vaporizing sprays from a high-pressure swirl injector using exciplex fluorescence method

The effects of ambient conditions on vaporizing sprays from a high-pressure swirl injector were investigated by an exciplex fluorescence method. Dopants used were 2% fluorobenzene and 9% DEMA (diethyl-methyl-amine) in 89% solution of hexane by volume. In order to examine the behavior of liquid and vapor phases inside of vaporizing sprays, ambient temperatures and pressures similar to engine atmospheres were set. It was found that the ambient pressure had a significant effect on the axial growth of spray, while ambient temperature had a great influence on the radial growth. The spatial distribution of vapor phase at temperatures above 473K became wider than that of liquid phase after half of injection duration, From the analysis of the area ratio for each phase, the middle part (region II) in the divided region was the region which liquid and vapor phases intersect. For liquid phase, fluorescence-intensity ratio was greatly changed at lms after the start of injection. However, the ratio of vapor phase was nearly uniform in each divided region throughout the injection.