A hydrogen cloud will burn within seconds, and all of the energy of the cloud will be released. However, if hydrogen gas mixtures enter confined regions, ignition is very likely and can result in flame acceleration and generation of high pressures capable of exploding buildings and throwing shrapnel.
A Comparison of Hydrogen and Propane Fuels Deflagration and Detonation During combustion, flames can propagate through a flammable fuel-air mixture as either a deflagration or a detonation, depending on a complex interaction among factors such as the composition of the gas mixture, the ignition source and energy, the geometry
Hydrogen Burning in Stars Hydrogen in induced reaction have lowest Coulomb barrier ⇒ highest reaction rate Hydrogen burning provides energy production in “Main Sequence Stars” in the HR Diagram (sun) until hydrogen fuel is depleted ⇒the life time of main sequence star depends on the reaction rates The stellar evolution, or subsequent
It is true that the Sun burns several hundred million tons of hydrogen per second, converting it to helium by nuclear fusion. This the source of the Sun's energy, and if the Sun were consuming gas at less than this rate, then we would not get the required warmth to support life.
Hydrogen has a high specific energy, high flame speed, wide range of flammability, and clean burning characteristics which suggest a possibility of high performance in internal combustion engines (ICE). These attributes have been realized for more than half a century since the onset of hydrogen engine development.
Before any of the effects you mention come to play a large part, the Sun will run out of hydrogen in its core and switch to burning helium instead--- causing many changes including the swelling of the star to a red giant with a radius approximately that of the Earth's orbit.
Burn rate (typically expressed in 'mm/s' or 'in/s') is the sample length over time at a given pressure and temperature. For solid fuel propellant, the most common method of measuring burn rate is the Crawford Type Strand Burning Rate Bomb System (also known as the Crawford Burner or Strand Burner), as described in MIL-STD-286C.
In this way the Sun consumes about 5 billion kilograms (5 million tons) of its nuclear hydrogen fuel every second. Yet the Sun is so large that it has been burning hydrogen at this rate ever since it formed some 5 billion years ago, and it will continue to burn steadily for at least another 4 billion years.
The size of the Hindenburg needs to be kept in mind. A passenger car or fuel cell operating on hydrogen would never have such a large amount of hydrogen stored in a flimsy cloth bag. All of the fuel cell systems and hydrogen storage techniques are engineered with safety being a paramount concern.
Changing the air to fuel ratio will change the burn rate of hydrogen.. A higher Oxygen to Hydrogen ratio will slow down the burn. In other words, a leaner mixture will slow down the burn rate. At the moment, I am disorganized and in need of major re organization of my information, but i did have a bit of a look for you.