On some older engines they use probe igniters, where there are a pair of probes which extend into the combustor and a spark jumps between them. I guess transistor exciters weren't particularly common in Eastern Bloc engines?
I never seen igniters which are sparkling between their tips. The problem is that increased air gap require extra high voltage to start ionization. Here we are discussing semiconductor igniters, that help to overcome this problem. Talking about semiconductor exciters, yes and no: most widely used exciters were with trembler, but recent models (which at the date are more that 30 years old) were semiconductor too.
How did the igniter spark almost instantaneously when you pushed the button? Wouldn't it take while to charge the capacitor? Also, out of curiosity, why is 27 VDC the chosen input voltage?
The first one is without the capacitor, so You can see that the spark power is really low. The igniter with two spark plugs is with capacitor, so there are mush less sparks per minute, but they are much more powerful. This helps to overcome several problems, especially: carbon deposits on the firing end can be burned out, better performance at low pressure (at high altitude required breakdown voltage is higher). AC power is more preferable, because it can be used directly without the trampler mechanism (or its solid-state analog). But the choice of supply depends on the type of airplane, and the main problem is that AC cannot be stored inside the batteries. (1) If this is a large airplane (e.g. B737,A320), its engines will be started with pneumatic starters, where the compressed air for the pneumatic starter is provided by the APU . In this case the AC can be generated by the APU too, so it is not a problem to have AC ignition system. (2) If the airplane is small, its engines will be starter by DC starter-generators. In that case DC starter-generator can run on battery power, without APU. Therefore, ignition system also should to operate on DC power, because when no engines are running, no generator will run, so there is no AC power on the airplane (only DC from the battery). In my example I had demonstrated DC powered ignition systems.
Wonder if these type of emitters can be used in cars? I mean it looks like very durable. Will it accumulate carbon? If it won't then we can modify them and install them on cars.
These ignition systems are designed to produce continuous sparkling (or repetitive sparks) for several minutes (maximum power, so called short duty) or infinitely long time (low power, so called continuous duty) to start or to support combustion process inside the combustion chamber of a gas turbine engine . That is, their exciters are not designed to provide sparks by ignition timing (as is required in piston engines). Talking about carbon accumulation, the high-tension ignition systems (i.e. high voltage systems) are installed on gas turbine engines here carbon buildup is a vital problem (due to high voltage they are able to strike carbon buildup). Low tension, which are cheaper, will not deal with carbon buildup.
@Denis Brodnev Does the voltage matter, not the amperes? I thought an exciter converted amps to increased voltage? And if so, does it really only take 24V to start a jet engine? That's crazy to me!
The voltage is significant here, because to brake the ignitter air gap a high voltage is required (approx. 15 kV / 1 mm). For this, the inginito exciter has a step-up transformer, which rise up the voltage up to several thousands volts (several kilovolts for the semiconductor igniter) or up to several tens of thousands volts if we talk about igniter with air gap (like in a typical car). Therefore, the high voltage is required to start the ionizing process (to break the air inside the air gap, thus initiate a spark). The next question is the energy. The spark duration is very short (several tens of microseconds). During this time very high current flow through the igniter (several hundreds of amperes). Such high current cannot be produced immediately; therefore, the exciter has high-voltage capacitor to store the energy. The step-up transformer rise up the supply voltage (e.g. 115 V) up to several kilovolts. Further, this AC voltage is applied to the rectifier. The rectifier output is DC. The DC voltage is then applied to the high-voltage storage capacitor. When the capacitor becomes fully charged, its output becomes connected to the ignitor, so very high voltage is applied to the igniter, where it break the air gap, so the ionized air starts to let the current (this is a spark). The capacitor discharges very quickly and the spark ends after several tens of microseconds. That's how the ignition system accumulates the energy to produce high-energy sparkling. Note that the supply current is relatively low (several Amps), but it is continuous and is used to continuously charge the capacitor. See Fig 11-10 aeromodelbasic.blogspot.com/2012/02/starting-and-ignition-ignition.html Note that if 27 VDC is used, the DC cannot be directly applied to the step-up transformer. In that case the mechanical or electric inverter is used. In my demonstration the mechanical inverter is used: there is vibrating contacts (so called Trembler) , that ON-OFF-ON-OFF-... (you may hear the buzzy sound of these contacts) the input 27VDC, so the supply is converted in pulses, and the pulses are AC voltage, so can be applied to the transformer.
@@Prathamsharma9765 At the date, I had wasted out all disassembled trembler mechanisms, so the only one way to know the material is to search it in a technical documentation and believe that it is listed there; but the tech.docs right now are not available to me.
Thank you for sharing! There is very few information regarding semiconductor type igniters. Your explanation is very useful
This is free?! Why did I pay the university when I could have just been on RUclips :|
Great video, thanks!
This video was filmed in the Institute of Aeronautics of Riga Technical University ;)
On some older engines they use probe igniters, where there are a pair of probes which extend into the combustor and a spark jumps between them.
I guess transistor exciters weren't particularly common in Eastern Bloc engines?
I never seen igniters which are sparkling between their tips. The problem is that increased air gap require extra high voltage to start ionization. Here we are discussing semiconductor igniters, that help to overcome this problem.
Talking about semiconductor exciters, yes and no: most widely used exciters were with trembler, but recent models (which at the date are more that 30 years old) were semiconductor too.
excellent video, thank you
Awesome Demo Denis!!
How did the igniter spark almost instantaneously when you pushed the button? Wouldn't it take while to charge the capacitor? Also, out of curiosity, why is 27 VDC the chosen input voltage?
The first one is without the capacitor, so You can see that the spark power is really low. The igniter with two spark plugs is with capacitor, so there are mush less sparks per minute, but they are much more powerful. This helps to overcome several problems, especially: carbon deposits on the firing end can be burned out, better performance at low pressure (at high altitude required breakdown voltage is higher).
AC power is more preferable, because it can be used directly without the trampler mechanism (or its solid-state analog). But the choice of supply depends on the type of airplane, and the main problem is that AC cannot be stored inside the batteries. (1) If this is a large airplane (e.g. B737,A320), its engines will be started with pneumatic starters, where the compressed air for the pneumatic starter is provided by the APU . In this case the AC can be generated by the APU too, so it is not a problem to have AC ignition system. (2) If the airplane is small, its engines will be starter by DC starter-generators. In that case DC starter-generator can run on battery power, without APU. Therefore, ignition system also should to operate on DC power, because when no engines are running, no generator will run, so there is no AC power on the airplane (only DC from the battery). In my example I had demonstrated DC powered ignition systems.
Wonder if these type of emitters can be used in cars? I mean it looks like very durable. Will it accumulate carbon? If it won't then we can modify them and install them on cars.
These ignition systems are designed to produce continuous sparkling (or repetitive sparks) for several minutes (maximum power, so called short duty) or infinitely long time (low power, so called continuous duty) to start or to support combustion process inside the combustion chamber of a gas turbine engine . That is, their exciters are not designed to provide sparks by ignition timing (as is required in piston engines).
Talking about carbon accumulation, the high-tension ignition systems (i.e. high voltage systems) are installed on gas turbine engines here carbon buildup is a vital problem (due to high voltage they are able to strike carbon buildup). Low tension, which are cheaper, will not deal with carbon buildup.
@Denis Brodnev Does the voltage matter, not the amperes? I thought an exciter converted amps to increased voltage? And if so, does it really only take 24V to start a jet engine? That's crazy to me!
The voltage is significant here, because to brake the ignitter air gap a high voltage is required (approx. 15 kV / 1 mm). For this, the inginito exciter has a step-up transformer, which rise up the voltage up to several thousands volts (several kilovolts for the semiconductor igniter) or up to several tens of thousands volts if we talk about igniter with air gap (like in a typical car). Therefore, the high voltage is required to start the ionizing process (to break the air inside the air gap, thus initiate a spark). The next question is the energy. The spark duration is very short (several tens of microseconds). During this time very high current flow through the igniter (several hundreds of amperes). Such high current cannot be produced immediately; therefore, the exciter has high-voltage capacitor to store the energy. The step-up transformer rise up the supply voltage (e.g. 115 V) up to several kilovolts. Further, this AC voltage is applied to the rectifier. The rectifier output is DC. The DC voltage is then applied to the high-voltage storage capacitor. When the capacitor becomes fully charged, its output becomes connected to the ignitor, so very high voltage is applied to the igniter, where it break the air gap, so the ionized air starts to let the current (this is a spark). The capacitor discharges very quickly and the spark ends after several tens of microseconds.
That's how the ignition system accumulates the energy to produce high-energy sparkling. Note that the supply current is relatively low (several Amps), but it is continuous and is used to continuously charge the capacitor. See Fig 11-10 aeromodelbasic.blogspot.com/2012/02/starting-and-ignition-ignition.html
Note that if 27 VDC is used, the DC cannot be directly applied to the step-up transformer. In that case the mechanical or electric inverter is used. In my demonstration the mechanical inverter is used: there is vibrating contacts (so called Trembler) , that ON-OFF-ON-OFF-... (you may hear the buzzy sound of these contacts) the input 27VDC, so the supply is converted in pulses, and the pulses are AC voltage, so can be applied to the transformer.
@@denisbrodnev627 May i know material of this Vibrating Contacts
I mean which metal is being used
@@Prathamsharma9765 At the date, I had wasted out all disassembled trembler mechanisms, so the only one way to know the material is to search it in a technical documentation and believe that it is listed there; but the tech.docs right now are not available to me.
@@Prathamsharma9765 I found one disassembled for You ibb.co/NnWGpbv Note two trembler contacts above and below the coil of the eelctromagnet.