Experimental and numerical assessment of an asymptotically correct choking mach number correlation for organic vapor flows through turbine cascades

An analytical expression for predicting the choking Mach number is presented. The expression is derived employing an asymptotic method leading to a perturbation series with a dominant zeroth-order term. Hence, it is suggested that actual choking Mach numbers can be predicted accurately in all practical organic vapor turbine design applications, including the dense gas regime. The reliability of this expression in the dilute gas regime is assessed using an experimental investigation of the flow of an organic vapor through a representative transonic turbine cascade. The agreement between the predicted and measured choking Mach number is excellent for the considered test case. To assess the validity of the expression for dense gas flows or flows largely different from the dilute gas regime, a database of computational fluid dynamics (CFD) simulations are utilized. Two different turbine cascades employing various organic working fluids and thermodynamic operating conditions are analyzed regarding the computed choking Mach number behavior.     «

An analytical expression for predicting the choking Mach number is presented. The expression is derived employing an asymptotic method leading to a perturbation series with a dominant zeroth-order term. Hence, it is suggested that actual choking Mach numbers can be predicted accurately in all practical organic vapor turbine design applications, including the dense gas regime. The reliability of this expression in the dilute gas regime is assessed using an experimental investigation of the flow o...     »