High Ignition Probability Research Articles

G0700704 旋回流動場における開口部を持つドーム形フランジ付き点火プラグの指向性

There is a problem to decrease the ignition probability while lean combustion improves that the thermal efficiency of spark ignition engines. Therefore, some techniques that improve the ignition probability are necessary in lean combustion. In the present study, the ignition and combustion characteristics of the spark plug with dome-shaped flanges were examined by using swirling flow fields. The result shows that the dome flanged spark plugs were high ignition probability compared with conventional plug. It is considered the reason was the effect of the collection of the shock wave energy and the effect of suppressing the flow in vicinity of the spark gap. Especially, in lean condition, the ignition probability of the dome flanged spark plug with three holes and the hole was arranged in straight for the flow was the highest. In other side, the combustion characteristic of the dome flanged spark plug with three holes and the hole not to face the flow was better than conventional plug and other dome flanged spark plugs.

Laser Ignition Microthruster Experiments on KKS-1

A laser ignition microthruster has been developed for microsatellites. Thruster performances such as impulse and ignition probability were measured, using boron potassium nitrate (B/KNO3) solid propellant ignited by a 1 W CW laser diode. The measured impulses were 60 mNs ± 15 mNs with almost 100 % ignition probability. The effect of the mixture ratios of B/KNO3 on thruster performance was also investigated, and it was shown that mixture ratios between B/KNO3/binder = 28/70/2 and 38/60/2 exhibited both high ignition probability and high impulse. Laser ignition thrusters designed and fabricated based on these data became the first non-conventional microthrusters on the Kouku Kousen Satellite No. 1 (KKS-1) microsatellite that was launched by a H2A rocket as one of six piggyback satellites in January 2009.

The method of laser-sustained arc ignition

The method of laser-assisted vacuum arc deposition (laser-arc) was developed to effectively produce high-quality coatings, especially multilayer coatings with a reduced number of droplets. The efficiency of this method depends mainly on the ignition probability of the vacuum arc discharges. In the present work, the process of arc initiation by laser irradiation is studied and the influencing factors such as power density of laser irradiation, target material, and electrode configuration are discussed. It is shown that a high ignition probability ( rho >50%) on such coating materials at Ti, TiC, TiN, and C can be guaranteed with a laser power density of about 10/sup 8/ W/cm/sup 2/, which can be achieved with a low-cost Nd-YAG pulse laser. Measurements of the plasma current preceding the arc ignition and microscopic investigations of the erosion pattern caused by the laser irradiation suggest that the process of plasma-sustained are ignition (unipolar arcing) plays an important role during the buildup phase of the vacuum arc discharge.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>