Mass is not increased by velocity... that is not how that works. The air is incompressible, so a set volume of air is always the same amount of mass no matter how fast it is going. You can calculate how much mass flow you have with a set volumetric cross section and velocity, but that does not change the MASS of the air in the cross section. Mass in this equation would only be changed based on the atomic composition of the material that would affect it's density and temperature. In most airflow calculations they just simplify to say that mass is unchanging since the air composition is always the same and it isn't doing any work, so temperature stays the same. The NASA link I gave you doesn't even have the mass portions in it, because it is unchanging in these cases.
The MASS in the equation is basically saying that if you threw a ball of wood(1lb) and a ball of lead(2lb) at the exact same speed, the ball of lead would only have .5lb more energy in it. If you throw that lead ball twice as fast, it now has 4lbs more energy in it(very simplified).