Abstract: The method allows to control a test apparatus for a gas turbine engine; WI values of one or more tentative fuel gas mixtures are predicted by calculations and the predicted WI values are used for setting the composition of a fuel gas mixture to be supplied to a combustor of a gas turbine engine under test. The test apparatus comprises: a first supply flow line for fuel gas; a second supply flow line for inert gas; a mixer with a first inlet for fuel gas and a second inlet for inert gas, and with an outlet for supplying the mixture of fuel gas and inert gas to the combustor; a set of meters; and a flow control device for the inert gas.

Abstract: A method for similitude testing of a turbomachine, the method comprising selecting a test gas having a molecular weight between 40 g/gmol and 150 g/gmol, a global warming potential (GWP) of less than 700, and a gas specific heat ratio of between 1 and 1.5; operating the turbomachine using the selected test gas; identifying at least one parameter while operating the turbomachine; establishing at least one test parameter associated with the at least one parameter; and comparing the at least one test parameter with a corresponding at least one specified parameter to determine whether the turbomachine has passed the similitude test.

Abstract: A method for similitude testing of a turbomachine, the method comprising selecting a test gas having a molecular weight between 40 g/gmol and 150 g/gmol, a global warming potential (GWP) of less than 700, and a gas specific heat ratio of between 1 and 1.5; operating the turbomachine using the selected test gas; identifying at least one parameter while operating the turbomachine; establishing at least one test parameter associated with the at least one parameter; and comparing the at least one test parameter with a corresponding at least one specified parameter to determine whether the turbomachine has passed the similitude test.