Thermodynamic Gas Model Effect on Gas Turbine Performance Simulations

Abstract

Engine performance prediction codes are used extensively in the aerospace industry by engine and aircraft manufacturers for a myriad of purposes that range from preliminary design and mission analysis to engine test and certification support. These codes require an equation of state to correlate the thermodynamic properties of the working gas, and in most cases it is the ideal gas equation the model uses. The suitability of the ideal gas assumption is often taken for granted, and no previous assessment of its accuracy can be found in the literature for gas turbine performance calculations. This paper investigates the accuracy of commonly used equations of state of gases to predict the p v T state of air in the operating range of the gas turbine and the deviation of the results from the ideal gas assumption in whole engine performance simulations. The equation of state of Soave has been found to provide the best accuracy within the gas turbine operating envelope. Results show that deviations of real models from ideal are of the order of 3% in cycle pressure, 1% in temperature and specific fuel burn, and 0.5% in specific thrust at part speed for a given fuel flow. Nomenclature A = Helmholtz function or potential, J a = equation of state coefficient B, C, D = Virial coefficients b= equation of state coefficient c = speed of sound, ms 1 c p = specific heat coefficient at a constant pressure, J Kg 1 K 1 c v = specific heat coefficient at a constant volume, J Kg 1 K 1 G = Gibbs function or potential, J H = enthalpy potential, J h = specific enthalpy, J Kg 1 k T = isothermal compressibility coefficient, Pa 1 , k T 1 v @v @p j T p = static pressure, Pa R = specific gas constant, J Kg 1 K 1 S = entropy potential, J K 1 s = specific entropy, J Kg 1 K 1 T = static temperature, K U = internal energy potential, J u = specific internal energy, J Kg 1 V = volume, m 3 v = specific volume, m 3 Kg 1 Z = compressibility factor = expansion coefficient, K 1 = ratio of specific heats p = polytropic efficiency = density kg m 3 Subscripts R = residual property r = reduced property

Transient Behavior in Variable Geometry Industrial Gas Turbines: A Comprehensive Overview of Pertinent Modeling Techniques

“…A comparison of some commercial software has been listed in the Table 6 . Variety of commercial and limited use in-house built software have been employed in the literature for transient modeling and validation of the developed models, i.e., GateCycle [ 40 , 45 ], DESTUR [ 26 ], GETRAN [ 58 , 219 ], TURBOMATCH [ 51 , 220 ], AMESim [ 42 ], Thermoflow [ 7 ], DYNGEN [ 32 , 221 ]. TERTS [ 222 ], TURBOTRANS [ 223 , 224 ], and FORTRAN based programs [ 50 , 51 , 206 , 225 ].…”

Blade Roughness Effects on Compressor and Engine Performance—A CFD and Thermodynamic Study

“…This allows for a considerable degree of flexibility to examine alternative GTE arrangements and operating conditions. A comprehensive description of the working principles and implementation of the Turbomatch suite can be found in [48][49][50].…”

Numerical study on the evolution law and correction method of turbine characteristics of the gas turbine under alternative fuel conditions

“…This model fully considers the influence of pressure. There are many kinds of state equations and a wide range of applications, but the calculation speed is slow, and the requirements for computing resources are high (Cravero and Satta, 2000;Boncinelli et al, 2004;Colonna et al, 2008;Harinck et al, 2010;Gallar et al, 2012;Mirko et al, 2012;Zhang et al, 2014).…”