Resonant Ignition Research Articles

Resonant dual-pulse laser ignition technique based on oxygen REMPI pre-ionization

This contribution investigates a novel laser ignition method based on a dual-pulse resonant pre-ionization scheme. The first laser pulse efficiently creates initial gas ionization (seed electrons) through a 2 + 1 resonantly-enhanced multiphoton ionization (REMPI) scheme targeting molecular oxygen (λ ~ 287.6 nm). This pulse is followed by a second non-resonant near-infrared pulse (λ = 1064 nm) for energy addition into the gas via inverse bremsstrahlung absorption. The sequence of two pulses creates a laser induced plasma that exhibits high peak electron number density and temperature (ne ~ 8 × 1017 cm-3 at t = 100 ns and T ~ 8000 K at t = 10 μs, respectively). These plasma parameters are similar to those attained for typical single-pulse near-infrared laser plasmas but with the advantage of substantially lower pulse energy (by factor of ~ 2.5) in the dual-pulse REMPI case. A combustion study focusing on ignition of propane/air mixtures shows that the dual-pulse REMPI method leads to an extension of the lean flammability limit, and an increase in combustion efficiency near the lean limit, as compared to laser ignition with a single NIR pulse. The measurement results and observed gas dynamics are discussed in the context of their impact on combustion applications.

Power Source Electronic Ballast for Electrodeless Fluorescent Lamps

This paper presents the design, control strategy and experimental results of a two-step, power factor correction stage (PFC) and resonant inverter (RI), electronic ballast proposal to supply 150 W electrodeless fluorescent lamps (EFL). The PFC acts as a controlled power source and provides mid and long-term stability to the system, while the stability of the current through the lamp is achieved with the RI. In addition, the power-mode control requires limitation of the output voltage. The dual operation mode of the PFC (voltage source mode and power source mode) enables an efficient soft resonant ignition and the implementation of simple dimming regulation.

Experimental Study of Multipoint Ignition in Methane–Air Mixtures by Pulsed Microwave Power

Microwave plasma offers a promising method to achieve faster combustion in internal combustion engine. In this paper, microwave multipoint ignition was confirmed via the high-speed imaging technique. The experiment was conducted with microwave resonant ignition system and optical system. A 2-ms, 3000-W, 2.45-GHz pulsed microwave power was used as energy source to produce initial flame kernel in combustion chamber. High-speed imaging was used to record the ignition characteristics via high-speed camera. Ignition experiments were conducted at high pressure of 2 bars of stoichiometric methane–air mixtures. It can be observed in the image and the pressure curves that multiple flame kernels are generated simultaneously. Faster combustion speed is achieved by pulsed microwave power ignition than traditional spark plug ignition in constant volume chamber.

Exploring microwave resonant multi-point ignition using high-speed schlieren imaging.

Microwave plasma offers a potential method to achieve rapid combustion in a high-speed combustor. In this paper, microwave resonant multi-point ignition and its control method have been studied via high-speed schlieren imaging. The experiment was conducted with the microwave resonant ignition system and the schlieren optical system. The microwave pulse in 2.45 GHz with 2 ms width and 3 kW peak power was employed as an ignition energy source to produce initial flame kernels in the combustion chamber. A reflective schlieren method was designed to illustrate the flame development process with a high-speed camera. The bottom of the combustion chamber was made of a quartz glass coated with indium tin oxide, which ensures sufficient microwave reflection and light penetration. Ignition experiments were conducted at 2 bars of stoichiometric methane-air mixtures. Schlieren images show that flame kernels were generated at more than one location simultaneously and flame propagated with different speeds in different flame kernels. Ignition kernels were discussed in three types according to their appearances. Pressure curves and combustion duration also show that multi-point ignition plays a significant role in accelerating combustion.

HID 가로등용 외장형 공진 점화기 제어 특성 비교

This paper presents a solution for designing an external resonant igniter control for high-intensity discharge (HID) lamps. In the case of a street lamp, the distance between the lamp and ballast is long. Therefore, parasitic capacitors and parasitic inductance depend on the length of the line affect the start-up time. Especially, in the case of resonant ignitor, ignition can be failed because the resonant frequency is influenced, and the voltage gain is changed. In this paper, resonant characteristic are compared and verified, depending on the distance in a topology and an algorithm of a resonant ignition. Additionally, the characteristics of external resonant igniter control are compared and analyzed through the frequency sweep experiment depending on distance.

원거리 공진 기동시 과전압 방지 HID 안정기

The electronic ballast for HID lamps needs to ignite lamps even though the length from the ballast to lamp is far away. Therefore, it needs to do the research on a resonant ignition to turn on the HID lamps because the reduction of ignition voltage is not much depending on the distance. However, the parasitic capacitance is increased depending the length of the cable, and it affects the resonant frequency. The ignitor voltage can be increased drastically under the resonant ignition through frequency sweep, and it is the main reason of blowing up. Therefore, the clamping diode is proposed to suppress the voltage of the primary winding during resonant ignition.

HID 램프용 Two-Stage 전자식 안정기의 과도 전류 제어

The conventional Three-Stage electronic ballast is stable, but Two-Stage electronic ballast has been researching because of efficiency. Three-Stage electronic ballast is consisted of PFC circuit, buck converter, and inverter circuit, but Two-stage is consisted of PFC circuit, Buck-Inverter full bridge circuit. The Buck-Inverter full bridge inverter consists of two half bridge inverters for low frequency switching, and high frequency switching. In the case of street lamp it is far from a lamp to a ballast, the conventional pulsed high voltage ignitor can not turn on the HID lamps because of reduction of ignition voltage. Therefore, it needs to do the research on a resonant ignition to turn on the HID lamps. Therefore, in the Two-Stage electronic ballast which has the resonant tank for ignition, the transient resonant current because of low frequency changing is analyzed, the novel algorithm is proposed to resuce the transient current.

Dynamic characteristics of a resonant gas-dynamic system for ignition of a fuel mixture

Results of an experimental study of specific features of operation of a resonant gasdynamic ignition system, as applied to initiation of liquid-propellant thrusters, are reported. Dynamic characteristics of the initiation process are determined. The behavior of the spectral characteristics of pressure oscillations in the combustor of a testbench model of a liquid-propellant thruster with ignition of the fuel mixture by the gas-dynamic system is considered.

Size Reduction in Low-Frequency Square-Wave Ballasts for High-Intensity Discharge Lamps Using Soft-Saturation Magnetic Material and Digital Control Techniques

This paper presents an approach to reduce the size of low-frequency square-wave (LFSW) ballasts by using a single stage for resonant ignition and LFSW operation together with soft-saturation magnetic material and digital control techniques. Inductor design constraints are developed to leverage the nonlinear inductor behavior and achieve both size reduction and desirable performance in lamp ignition, warm-up, and normal operation modes. The digital controller provides multiple functions, including 1) a phase-controlled resonant sweep to achieve reliable lamp ignition and device protection with zero-voltage switching despite the nonlinear tank inductance, 2) lamp ignition detection and rapid transition to LFSW mode for lamp warm-up, 3) fast LFSW polarity transitions with optimal timing control for acoustic resonance free operation, and 4) two-loop feedback control. A fast current control loop limits and stabilizes the lamp current and rejects large ripple from the power factor correction (PFC) stage in order to reduce the size of the PFC output capacitor. A slow power control loop rejects variations in the lamp characteristics during warm-up and lamp aging. Experimental results are presented showing successful ignition and operation of a 150-W high-intensity discharge lamp.

Digitally Controlled Low-Frequency Square-Wave Electronic Ballast With Resonant Ignition and Power Loop

This paper proposes a digital controller for a low-frequency square-wave (LFSW) electronic ballast that includes the ignition sequence, a double control loop, and the selection of the positive and negative operation modes. The whole ballast is a two-stage circuit, where the first part is a power factor correction (PFC) stage and the second is a full-bridge (FB) converter used for both ignition and square-wave drive. Ignition is achieved by approaching the resonant frequency of the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> filter when the lamp is in the off state and the FB is working as a resonant inverter. After ignition, the converter operates as an LFSW inverter by controlling the FB to act alternately as a buck converter supplying positive or negative current. While ignition occurs at the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> filter resonance frequency ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sub> = 20 kHz), the buck converter switching frequency ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">sw</sub> = 200 kHz) is selected significantly higher than <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">f</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sub> to attenuate high-frequency harmonics and avoid exciting acoustic resonance. Lamp stability is achieved by controlling the inductor current of the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> filter, and power mode control is achieved by adjusting the average current and voltage supplied by the PFC stage. The solution is experimentally validated for different types of 150-W high-intensity discharge lamps. A coupled-inductor single-ended primary inductance converter operating in continuous conduction mode is used for the PFC stage.

Resonant Laser Ignition Study of HAN-HEHN Propellant Mixture

Resonant laser ignition at wavelengths in the UV and IR was demonstrated for hydroxyl ammonium nitrate (HAN)–hydroxyethylhydrazinium nitrate (HEHN) mixtures. This prototypical ionic liquid propellant was successfully and reliably ignited under confinement with single laser pulses in the mid IR at 2.94 and 10.6 µm. UV wavelengths at 193 and 248 nm were also resonant with sample absorption, but they did not lead to ignition with the available excimer laser pulse energies. The results are consistent with absorption of the IR laser pulse within a short path length, efficient V→T relaxation, and thermal decomposition of HAN that leads to additional chemical reaction and ignition of milligram samples within tens of microseconds.

Acoustic Response of a Resonant Igniter with Confuser Inlet

Acoustic Response of a Resonant Igniter with Confuser Inlet

Study of Igniter in Low-Frequency Square Wave Electronic Ballasts for Metal Halide Lamps

Metal halide lamps (MHLs) have serious acoustic resonance problem. The most widely used method to achieve acoustic-resonance free is to use low-frequency square wave (LFSW) electronic ballasts. There are two ignition methods commonly used in LFSW electronic ballast: high-frequency resonance ignition and additional pulse igniter. This paper analyzed the problems during ignition while using the conventional additional pulse igniter and proposed some solutions. A novel high-frequency resonance igniter is also proposed, where no extra semiconductors and feedback control circuit are needed to perform the ignition. High-voltage ignition pulses are obtained by utilizing the fast polarity inversion of the output voltage of full-bridge inverter. Theoretical analysis, simulation, and experiment results of a prototype for 70-W MHLs verified the effectiveness of both the proposed solutions and the igniter.

Proactive Mitigation of PCTFE-Related Ignition Hazards in Oxygen Systems: I. Development of a Voluntary Consensus Standard Specification to Control Property Variation in Finished PCTFE Parts

Abstract Revelations of dimensional instability in polychlorotrifluoroethylene (PCTFE) semifinished articles and finished parts raised concerns that leaks or part failure could occur during service, leading to catastrophic component or system failure, especially in high-pressure gaseous oxygen systems where flow friction, flow resonance, or kindling chain ignition mechanisms are operative. These concerns culminated in the release of an internal NASA Kennedy Space Center Problem Advisory and a Government-Industry Data Exchange Program Problem Advisory on PCTFE. Release of the advisories coincided with a task group study examining the factors contributing to property variation in PCTFE. More specifically, the effect of resin grade, process route, annealing method, and machining on dimensional stability, molecular weight, and crystallinity was determined. To better control dimensional stability, for example, a Biot-Fourier method is described that allows calculation of the time needed for PCTFE parts of known geometry to reach thermal equilibrium during annealing. A voluntary consensus material specification was then implemented to control properties in finished PCTFE parts used in aerospace applications.

Investigation of Novel Hydrogen/Oxygen Thruster for Orbital Maneuver in Space Station

Hydrogen and oxygen orbital maneuver thruster, based on gas dynamic resonance ignition, is a new liquid rocket propulsion technology, and is especially applicable to space station. By means of theoretic thermodynamic calculation of the hydrogen and oxygen thruster, combined with the experimental exploration on the coaxial hydrogen and oxygen resonance ignition, a scheme of the thruster head configuration is designed as the combination of a coaxial hydrogen/oxygen resonance igniter and an oxygen augmentation injector. Through ignition tests on coaxial hydrogen/oxygen resonance igniter characterization, the thruster head ignition tests have been conducted successfully in sequence of resonance ignition and oxygen augmentation combustion. Finally, the thruster ground tests are successfully carried out informs of single impulse, successive double impulses and 3. 0 seconds continuous running, which verify the reliability and feasibility of the thruster. The response time of the thruster starting is restricted within 0.2 second.

Development of a Resonance Igniter for GO/Kerosene Ignition

A resonance ignition system is attractive for rocket engines because of the igniter’ s simplicity and the possibility of multiple ignitions without additional mechanical complexities. In this work a resonance igniter to produce a torchfromburning ofgaseousoxygenandliquidkerosenewasdesignedandtested.Theoxygen isheatedfor0, 1sin the acoustic resonator cavity, and the ignition occurs instantaneously on kerosene injection. The preliminary tests under ambient conditions demonstrated the igniter’ s ability to ignite GO 2/kerosene mixtures over a wide range of pressures and mass e ow rates. This opens new possibilities to create a compact and reliable ignition system for restarting rocket engines. Nomenclature P m f; P mo = mass e ow rate of kerosene and oxygen, respectively, kg/s O=F = P mo= P m f , mixture ratio pc = chamber pressure, bar p f; po = inlet pressure of kerosene and oxygen, respectively, bar TB = temperature of the igniter body, K TR = temperature of the outer surface of resonator, K TT = temperature of the torch, K t = time, s t f = moment when the fuel valve is turned on, s tig = moment of ignition, s to = moment when the oxygen valve is turned on, s toff = moment when the fuel valve is turned off, s 1tig = time delay of ignition, s 1to = igniter preparation interval, s 1top = igniter operation interval, s

Experimental Investigation of Pulsatile Flow in Circular Tubes

Conclusions An ignition system based on resonance igniter was designed and tested, which 1) can operate independently of engine propellant lines only at the cost of the energyof stored compressedoxygen;2) contains reduced number of components and can be designed as a modular unit, for a wide range of mass  ow rate and mixture ratio; and 3) allows up to eight ignitions with an oxygen tank of 2.4 L under 170 bar, for 2 s of torch duration and 33 ¢ 10 3 kg/s of torch  ow rate.

Modular Ignition System Based on Resonance Igniter

Modular Ignition System Based on Resonance Igniter

Aerothermodynamics of a Simple Resonance Tube

An experimental investigation of a simple resonance ignition tube has been conducted. The leading edge of the resonance tube was blunt in order to simulate the geometry of proposed rocket ignition systems. The jetstagnation pressure, the nozzle/resonance-tube separation distance, and the resonance-tube length were varied systematically. Strong resonance was found to occur when the leading edge of the resonance tube was located within the third compression cell of the underexpanded jet. High-speed motion pictures showed a significant upstream propagation of disturbances from the resonance tube to the nozzle. These results will be useful in determining the feasibility of using resonance-tube ignition systems for both liquidand solid-propellant rocket engines.

A resonance igniter for hydrogen-oxygen combustors

A resonance igniter for hydrogen-oxygen combustors