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A special reference densimeter has been developed for accurate measurements of densities of natural gases and multicomponent gas mixtures at standard conditions of temperature and pressure (T s = 273.15 K and p s = 0.101325 MPa). The densimeter covers the range from 0.7 kg · m −3 to 1.3 kg · m −3 ; the total measurement uncertainty in density is 0.020 % (95 % level of confidence). The measurement principle used is the two-sinker method, which is based on the Archimedes buoyancy principle. The certified calibration laboratory of E.ON Ruhrgas AG, Germany, uses this densimeter to verify the standard densities of certified calibration gases (binary and multicomponent gas mixtures). Moreover, the densimeter is used to determine the compositions of commercially available binary gas mixtures with a small uncertainty of (0.01-0.03) mol%.

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Today’s steam turbine power plants are designed for highest steam inlet temperatures up to 620°C to maximize thermal efficiency. This leads to elevated thermal stresses in rotors and casings of the turbines. Hence, temperature distributions of the components have to be predicted with highest accuracy at various load points in the design process to assure reliable operation and long life time. This paper describes the windage heating effect in full labyrinth seals used in steam turbines. An analytical approach is presented, based on CFD simulations, to predict the resulting steam temperatures. A broad application range from very low to highest Reynolds numbers representing different turbine operation conditions from partial to full load is addressed. The effect of varying Reynolds number on the flow friction behaviour is captured by using an analogy to the flow over a flat plate. Additionally, the impact of different labyrinth geometries on the friction coefficient is evaluated with the help of more than 100 CFD simulations. A meta-model is derived from the numerical results. Finally, the analytical windage heating model is validated against measurements. The presented approach is a fast and reliable method to find the best performing labyrinth geometries with lowest windage effects, i.e. lowest steam temperatures.