Injector Structure Research Articles

Dynamics optimization of coupling atomization process in an injector achieved by novel micro laser powder bed fusion

This study employed large eddy simulation and a volume-of-fluid with discrete phase model to evaluate a swirl fuel injector's atomization performance. Addressing non-uniform atomization at low flow rates, the study optimized a swirl injector structure based on additive manufacturing advantages during re-modeling. Computational analysis revealed that vortex downstream and capillary bubbles caused non-uniformity in the prototype injector, mitigated by the optimized injector's three-dimensional flow channel. Comparative analysis showed similar parameters between the optimized and prototype injectors, except for significant improvement in circumferential uniformity at low flow rates (from 41.48% to 14.69%). The optimized injector's swirl structure, produced via micro laser powder bed fusion, exhibited precise dimensions and minimal surface roughness. Validation experiments without air inflow confirmed the computational results' reliability, with a minor discrepancy in circumferential uniformity (2.98%) and atomization cone angle (2.3°) for the prototype swirl structure. At low flow rates, the optimized structure showcased reduced circumferential non-uniformity (from 42.31% to 28.76%), underscoring its benefits. This interdisciplinary investigation underscores additive manufacturing's application in structural optimization and manufacturing.

Structural parameters of venturi injector for periodic air recovery based on response surface methodology

This work is devoted to the study of the structural parameters of a venturi injector for periodic air recovery. Using a push chain concrete spraying machine as a case, a numerical simulation study was conducted on the venturi injector under different structural parameter combinations. The venturi injector structure parameters diameter ratio of the throat to pipe a, convergent angle α, throat length to diameter ratio b, and diffusional angle β are designed and combined by the response surface method. The numerical simulation results and the prediction model obtained by the response surface method were verified by experiments, and the simulation results and prediction model were in good agreement with the experimental results. The results show that the residual air recovery of the push chain concrete spraying machine is best when a, α, b, and β are 0.8, 25°, 2.5, and 10°, respectively. In addition, the quadratic polynomial response surface model of the venturi injector pressure variation coefficient Cv and pressure drop Pd concerning the structural parameters was established, and the influence rules of each structural parameter on the Cv and Pd were obtained. The variation patterns of turbulent kinetic energy in the venturi at different times and stable sections at the back end are revealed. This paper can provide help for the design of venturi structures used for periodic air recovery in other chemical fields.

Room-temperature spin injection and optical polarization in nitride-based blue and ultra-violet spin light-emitting diodes

RT spin injection and optical polarization in nitride-based spin-LEDs are investigated. By employing CoFeB/MgO as the spin injector, the spin relaxation time and diffusion length in n-type GaN film are revealed to be 54.9 ps and 214.4 nm, respectively, through the three-terminal Hanle measurement. As the spin injector structure is applied to blue spin-LED, a maximal circular polarization of 3.3% is detected in electroluminescence, with the surface-emitting geometry and under a vertical magnetic field. UV spin-LED with n-Al0.05Ga0.95N transport layer is also fabricated, whose optical polarization is relatively smaller due to the larger spin–orbit coupling in Al atoms.

Modulating room temperature spin injection into GaN towards the high-efficiency spin-light emitting diodes

Spin injection performance in GaN film was systematically investigated through the three-terminal Hanle spin precession measurements with the comparison of varied tunnel barrier thickness, spin injector materials, and channel widths. Spin relaxation time and diffusion length were optimized to 37.3 ps and 139.0 nm at room temperature, respectively. With the optimal spin injector, a 12% spin polarization was obtained in a four-terminal non-local spin valve device. By applying the optimized spin injector structure to the spin-light emitting diodes, room temperature circular polarization ratios of 6.2% and 9.2% for Co and Fe spin polarizers were respectively achieved at surface-emission.

Strength Analysis of the CNG Direct Injector for the Combustion Ignition Engine in Real Driving Conditions

The paper presents the results of strength test simulations of the CNG injector structure for direct injection of compression-ignition engines. This article is a continuation of the works presented in paper [1]. Life cycles estimation of particular parts of the injector were calculated using the Kocańda relation. The simulation tests of injector strength carried out earlier have allowed us to determine the stress concentration points. On the basis of NEDC driving tests carried out in three different cars, engine load histograms were made for subsequent runs and an average load profile was determined. For the points most exposed to damage,i.e.the needle and injector housing, the stress curve was generated as a function of time. This dependence was the base for fatigue calculations with the use of MatLab program in order to calculate the limit number of repetitions for a given injector element. All the calculation works have served to determine the maximum number of work cycles of a given injector design.

Piezo-actuated common rail injector structure and efficient design

Piezo-actuated common rail injectors are often utilized in today’s automobile engines’ fuel systems. This high-tech instrument decreases fuel consumption, thereby harmful exhaust emissions are also lowered especially in diesel ignition engines. Owing to ultra-high pressure in piezo-injection systems, fuel droplets are scaled down into a smaller particle form and thus provided more efficient combustion. Pulverized fuel droplets are evaporated and oxidized in a very short time and they provide exact combustion inside the combustion chamber. In this study, numerical simulation of a piezo-actuated common rail injector fluid-mechanical model with detail is demonstrated. The hydraulic and mechanical component interaction is modeled through the fluid-mechanical components. Thus, the piezo injector dynamics are predicted based on the geometry and the physical quantities describing the equipment. Input voltage in the entrance is used to describe the piezo actuator force for piezo-electric material. In model, fuel flows from the common rail to a tee that separates the flow into two paths: fuel gallery and valve with the inlet orifice. Using this detailed model, behavior of the piezo injector, effects of the injector parameters on the fuel flow were investigated numerically and results were represented.

GaN-Based Light-Emitting Diodes With Staircase Electron Injector Structure

The authors experimentally studied GaN-based light-emitting diodes (LEDs) with both an staircase electron injector (SEI) structure and a conventional electron blocking layer (EBL). With the EBL, it was found that we could enhance LED output power, reduce forward voltage, and mitigate efficiency droop by inserting the SEI structure. These improvements could all be attributed to the effective cooling of the injected hot electrons. However, it was also found that some of the injected electrons could still leak into the p-GaN layer in the LED with SEI structure but without the EBL.

Experimental Research on the Propagation Process of Continuous Rotating Detonation Wave

Abstract In order to study the propagation mechanism of continuous rotating detonation wave, the H 2 /air continuous rotating detonation engine ignited by tangentially installed H 2 /O 2 pre-detonation tube is studied experimentally using a tilt slot injector structure. The experimental results show that the stable rotating detonation wave can be gained successfully with the equivalent ratio of 0.93. The propagation frequency and velocity of rotating detonation wave range from 5200 to 5500 Hz and from 1518.5 to 1606.1 m/s, respectively. Three propagation modes, such as rotation, reversal and bifurcation, of detonation wave are verified through the analysis of propagation mechanism of rotating detonation wave.

부유게이트에 지역전계강화 효과를 이용한 아날로그 어레이 설계

1.2 더블 폴리 부유게이트 트랜지스터로 구성된 아날로그 메모리가 CMOS 표준공정에서 제작되었다. 효율적인 프로그래밍을 위해 일반적인 아날로그 메모리에서 사용되었던 불필요한 초기 소거 동작을 제거하였으며 프로그래밍과 읽기의 경로를 동일하게 가져감으로서 읽기 동작 시에 발생하는 증폭기의 DC 오프셋 문제를 근본적으로 제거하였다. 어레이의 구성에서 특정 셀을 주변의 다른 셀들로부터 격리시키는 패스 트랜지스터 대신에 Vmid라는 별도의 전압을 사용하였다. 실험 결과 아날로그 메모리가 디지털 메모리의 6비트에 해당하는 정밀도를 보였으며 프로그래밍 시에 선택되지 않은 주변의 셀들에 간섭 효과가 없는 것으로 확인되었다. 마지막으로, 아날로그 어레이를 구성하는 셀은 특이한 모양의 인젝터 구조를 가지고 있으며, 이것은 아날로그 메모리가 특별한 공정 없이도 트랜지스터의 breakdown 전압 아래에서 프로그래밍 되도록 하였다. An analog array with a 1.2 double poly floating gate transistor has been developed with a standard CMOS fabrication process. The programming of each cell by means of an efficient control circuit eliminates the unnecessary erasing operation which has been widely used in conventional analog memories. It is seen that the path of the signal for both the programming and the reading is almost exactly the same since just one comparator supports both operations. It helps to eliminate the effects of the amplifier input-offset voltage problem on the output voltage for the read operation. In the array, there is no pass transistor isolating a cell of interest from the adjacent cells in the array. Instead of the extra transistors, one extra bias voltage, Vmid, is employed. The experimental results from the memory shows that the resolution of the memory is equivalent to the information content of at least six digital cells. Programming/erasing of each cell is achieved with no detectable disturbance of adjacent cells. Finally, the unique shape of the injector structure in a EEPROM is adopted as a cell of analog array. It reduces the programming voltage below the transistor breakdown voltage without any special fabrication process.

Numerical investigation of pressurization performance in cryogenic tank of new‐style launch vehicle

ABSTRACTThe pressurization performance of cryogenic tanks during discharge is investigated by a computational fluid dynamic approach. A series of cases accounting for the effects of various influence factors such as inlet gas temperature, ramp time of inlet gas temperature, wall thickness, outflow rate, injector structure, and liquid supercooling on pressurization behaviors are computed and analyzed successively. Several valuable conclusions have been drawn as follows: (1) Increasing inlet gas temperature, applying a thin wall to construct the tank, and increasing the outflow rate are beneficial to the reduction of gas requirements, (2) Ramp process and use of a straight pipe injector may lead to an excessive pressure drop at the beginning of discharge, (3) Use of straight pipe injector can remarkably reduce the gas requirement but lead to a large loss of liquid propellant as well as a large weight of final ullage gas, and (4) The mode of mass transfer within the tank is close related to the injector structure and liquid supercooling. A trend of mass transfer toward evaporation can be observed by increasing the liquid temperature, especially for the straight pipe injector case. Generally, the results of this paper might be beneficial to the design and optimization of a pressurization system. © 2013 Curtin University of Technology and John Wiley & Sons, Ltd.

CFD investigation of thermal and pressurization performance in LH2 tank during discharge

Predictions of thermal and pressurization performance in a liquid hydrogen (LH2) tank during liquid discharge is of significance to the design and optimization of a rocket pressurization system. In this paper, a computational fluid dynamic (CFD) model is introduced to simulate the pressurized discharge event of LH2 tank. The wall region together with the fluid region is simultaneously considered as the computational domain, and low-Re k–ε model is applied to account for the fluid-wall heat exchange effect. Liquid–vapor phase change effect is also involved in the model. Comparison of the numerical results with existing experimental data suggests that the CFD model has a good adaptability in pressurization computation. Detailed characteristics, such as pressurant gas requirement, pressure altering history, and temperature distribution inside the tank, can be obtained by the model. The difference of pressurant gas, selecting helium or vapor H2, may result in the variations in pressure and temperature histories. Pressurization by vapor H2 supplies a higher pressure and also a temperature rise, which is significant to consider the selection of pressurant gas. The influences of phase change effect and injector structure on pressurization behaviors are also analyzed. The computational results show that liquid–vapor phase change has a slight influence on the pressurization behaviors. Significant pressure decay at the beginning stage of process may occur in the case of no-diffuser injector application since the incoming gas is excessively cooled by cold LH2. The results show that the present CFD model has a good adaptability in the prediction of pressurization behaviors and is a useful tool for the design and optimization of a pressurization system.

Optimized Design of Structure Parameter of New Fuel Injection System

According to the characteristics and the future tendency of common rail systems for marine diesel engines，the paper used a new injector. A simulation model of the common rail system with new injector was established using HYDSIM system, pressure fluctuation of the common rail pipe and pressure loss of the injector as evaluation indicator, the injector was simulated and optimized using DOE method. Simulation results show that appropriate selection of the structure parameters of the injector structure can effectively prevent the injectors from interfering each other and degree pressure loss of injector.

LPG인젝터의 누설성능 향상에 관한 연구

우리나라의 LPG자동차 기술은 2003년 LPG액상분사방식 차량의 양산을 계기로 크게 발전하기 시작하였으며, 지금까지 관련기술의 발전을 거치면서 SULEV 배출가스 규제를 만족하는 수준에 이르렀다. 우리나라의 LPG자동차 등록수는 240여만 대를 넘어서면서 세계 1위의 LPG자동차 보유수를 보이고 있다. 그러나 이러한 많은 대수를 보유하고 있음에도 불구하고, 지금까지 LPG자동차의 핵심 연료시스템은 외산기술을 이용하는 라이센스 제작, 조립 및 판매를 진행하고 있다. 특히 LPG액상분사식 자동차의 핵심부품인 LPG인젝터는 국제 부품공급사인 C사의 D 인젝터를 이용하여 왔다. 이에 본 연구에서는 국산 LPG인젝터의 개발을 이루고자 하며, 개발과정에서 가장 핵심적인 LPG 누설성능 개선에 영향을 미치는 코팅기술의 성능향상연구를 집중하였다. 본 연구에서 WCC 코팅 및 구조 최적화를 통하여 기존의 D 인젝터의 0.06cc/min 누설성능을 0.04cc/min 수준 이하로 낮출 수 있었다. The LPG engine technology in Korea has made significant advances with the mass production of LPG vehicle with liquid phase LPG injection system, and have reached to satisfy the SULEV emission regulations. As of now, domestic production of LPG fuelled vehicles in Korea have reached more than 2.4 millions, which is the best in the world. But in the technical point of view, the key technologies for fuel injection system of LPG fuelled engine are mainly dependent on foreign license. Especially, fuel injector in the liquid phase LPG injection system has been imported from C company, which supplies LPG injector worldwide in the name of model D. In the context, it is quite urgent to develop the LPG injector technology in Korea. In this study, WCC coating which is key technology to develop LPG injector by reducing the fuel leakage was developed and tested. Considering the fuel leakage of 0.06cc/min in commercial LPG injector, fuel leakage was reduced down to 0.04cc/min with WCC coating technology and optimization of injector structure.

Design and Optimization of Injector Structure in Diesel Engine Based on ISIGHT Platform DOE Methods

The traditional design method of injector structure cannot meet the demand of farther improved performance,the change of modern environment demand not only the optimization of one performance but also the optimization of various comprehensive performance.iSIGHT is a multidisciplinary design optimization platform that offer a integrated designenvironment and advanced design optimization methods. The optimization design of injector structure based on design of experiment of iSIGHT platform to improve the spray quality of injector is implemented.

A simple method for determination of Fowler–Nordheim tunnelling parameters

A simple technique for extracting the Fowler–Nordheim (FN) tunnelling parameters is proposed. It consists of measuring the Drain-Source current of a floating gate transistor while a linear ramp voltage is applied to a simple injector structure attached to the transistor's floating gate. Such a test device is fabricated using a standard CMOS process. The parameters obtained can be used in a freely available electrical simulator as SPICE3f5 (NGSPICE), but in general it can be easily adapted to other SPICE-like programs. We describe the technique step-by-step and a comparison is made of simulated and measured FN tunnelling parameters, for a floating gate transistor with tunnelling injectors. A good agreement has been found between experimental and simulated data.

Design and Fabrication of Monolithic Multidimensional Data Registration CMOS/MEMS Ink-Jet Printhead

A monolithic ink-jet printhead is designed and fabricated with back-shooting type of thermal bubble nucleation for high-speed and long-life printing in this paper. It combines micromechanics, including heating actuators, temperature sensor, channels, and nozzles, with an integrated multidimensional data registration CMOS demultiplexer driving circuit, which includes D flip-flop signal processing along with bidirectional data transfer and 12-V power amplifiers in a printhead chip. Microelectromechanical systems fabrication processes are applied to define the ink-firing chamber, feed channel, and the orifice plate within this new micro injector structure. In this paper, the printing resolution of this monolithic ink-jet head is 1200 dpi, and the diameter of nozzle orifice is about 14 μm with a thickness of 30 μm. Both the silicon dry and wet etching processes are applied to the fabrication of orifice plate with the control of thickness within ±4 μm. The major advantage of the ink-jet chip assembly processes is that throughput is improved. The operating frequency of the monolithic ink-jet printhead developed in this paper is 24 kHz. The required voltage to start the bubble nucleation of printer head is 7.4 V, and the ink nozzle lifetime is 1.5 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sup> . The optimization design of this monolithic ink-jet printhead could provide better printing quality than the commercial ones.

Quantum-well band structure effects on the emission polarization from a spin-polarized electron reservoir

Many spin-polarized-based devices utilize the optical polarization from semiconductor quantum wells (QWs) as a read out. Under ideal conditions at zero crystal momentum, 100% optical polarization is obtained from these QWs for fully polarized electrons. However, carrier populations typically extend over nonzero crystal momentum states, where band mixing results in nonideal optical polarization. We investigate a single InxGa1−xAs(x=0.2, and 0.08)QW in GaAs in a typical p-i-n spin injector structure, using eight band k.p theory including strain, electric field and quantum-confined Stark effects. By evaluating the carrier distribution and wave functions of the QW states, we find the resulting optical polarization is reduced to ∼60% at 10K, and further for high temperature and high fields. We show that under certain conditions we can flip the sign of the optical polarization, suggesting the possibility of an electric field controlled optical or spin polarization switch.

EEPROM Cell Design for Molybdenum Gate Analog BECMOS Process

A floating capacitor with a MOS charge injector structure can be used as a nonvolatile memory. This type of memory device can be embedded into an analog MOS technology with capacitors. In this article the feasibility of the structure for small scale embedded memory is studied with 1.5µm analog ASIC molybdenum gate technology.

Ballistic transport through GaAs–AlGaAs superlattices in transverse magnetic fields

In this work, ballistic electron transport through the lowest miniband of a biased GaAs–AlGaAs superlattice is investigated in transverse magnetic fields. As method we employ a solid-state version of ballistic electron emission microscopy/spectroscopy using a metal-insulator-metal injector structure that replaces the tip of the scanning tunneling microscope (STM). The ballistic electron current measured as a function of the collector bias shows a peak at flatband conditions indicating coherent transport through the superlattice miniband. With increasing transverse magnetic fields, this peak is quenched and evidence of sequential LO-phonon scattering inside the superlattice is found. Using an extended transfer matrix method, the observed effects are quantitatively explained; differences to previous STM based measurements are discussed.

Metal–insulator–metal injector for ballistic electron emission spectroscopy

We introduce a solid-state version of ballistic electron emission microscopy/spectroscopy (BEEM/BEES) on GaAs–AlGaAs heterostructures using a metal–insulator–metal (MIM) injector structure that replaces the tip of the scanning tunneling microscope (STM). In the present work, the MIM injector is realized by an Al–Al2O3–Al tunnel junction yielding an easy-to-fabricate three-terminal device for ballistic electron spectroscopy. The device principle is applied to several GaAs–AlGaAs structures. The barrier heights obtained from the onsets of the ballistic current spectra are in good agreement with self-consistent calculations as well as earlier experimental results achieved with STM-based BEES.