Row-by-row off-design performance calculation method for turbines

Abstract

The turbine component of a gas turbine engine is frequently subjected to extreme operation conditions associated with significant changes in mass flow, turbine inlet temperature, pressure and rotational speed. These off-design operation conditions significantly affect the flow deflection within the turbine stage, which consists of individual stator and rotor rows. As a result, the stage parameters representing the velocity diagram will change and affect the efficiency and performance of the stage and, thus, the turbine. A row-by-row calculation method is presented for predicting the performance behavior of turbines under extreme off-design conditions. The method is applied to a multistage turbine for which the off-design performance is calculated and compared with the measurement. Nomenclature b= blade height D = diameter /z, H = specific static, total enthalpy L = stage power l m = stage specific mechanical energy ra = mass flow /?, P = static, total pressure r = degree of reaction T.= temperature (7, V, W = velocity vectors a = absolute flow angle j8 = relative flow angle y = cascade parameter £ = loss coefficient r) == row efficiency A = stage load coefficient f4 = ratio of meridional velocities v = ratio of circumferential velocities £ = auxiliary function p = density $ = stage flow coefficient X, ¥ = dimensionless isentropic enthalpy coefficients o>, £1 = turbine angular velocity, angular velocity ratio Subscripts D = dissipation m = mechanical energy, mean m, u = meridional, circumferential direction P, 5, C = primary, secondary, clearance (losses) s = isentropic w = windmilling 1, 2, 3 = stations shown in Fig. 1

Aero-thermodynamic and chemical process interactions in an axial high-pressure turbine of aircraft engines

“…The principal sources of these losses in the axial turbine are profile, shock, tip-leakage, and end-wall losses, which have already been reported by Wei 51 and discussed by many authors. [52][53][54][55][56][57][58][59][60][61] Concerning the velocity variation in the HPT, the velocity gradient in the stator was positive because the static enthalpy of temperature was then converted to kinetic energy. So, in the stator, the fluid was accelerated, while the temperature decreased in the rotation direction.…”

Modeling Mach Number and Temperature Distributions in Supersonic Nozzle Flow

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The ultra-high efficiency gas turbine engine, UHEGT, part III: Dynamic behavior of the system in variable performance conditions

“…The mechanical energy output L R is determined from the specific polytropic stage output as comprehensively discussed in Schobieri and Abouelkheir. 23,24 Shaft: The shaft's rotational speed is determined by…”