Abstract: A method and apparatus for automatically maintaining gas turbine NO.sub.x emissions at a substantially constant level during all ambient conditions and for no load to full load fuel flows. The required water/fuel ratio is calculated for a substantially constant level of NO.sub.x emissions at the given operating conditions and, knowing the actual fuel flow to the gas turbine, a signal is generated representing the water metering valve position necessary to inject the proper water flow into the combustor to achieve the desired water/fuel ratio.

Abstract: This invention relates to a method of achieving a desired fuel/oxygen mass ratio in an internal combustion engine for an existing ambient air temperature comprising of the steps of determining a desired fuel/air differential pressure corresponding to the desired fuel/oxygen mass ratio for said engine at any particular ambient air temperature; and adjusting the fuel flow to said engine to achieve the desired differential fuel/air pressure. The invention also comprises apparatus for achieving a desired fuel/oxygen mass ratio in an internal combustion engine for an existing ambient air temperature comprising means for determining a desired fuel/air differential pressure corresponding to a desired fuel/oxygen mass ratio for said engine at any particular ambient air temperature; and means for adjusting the fuel flow to said engine to achieve the desired fuel/air differential pressure for the existing ambient air temperature.