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Abstract

The article discusses issues associated with the use of modern plastics for the construction of high-speed fluid-flow machines. Currently available plastics exhibit high chemical resistance as well as dimensional and shape stability across a wide temperature range. This allows them to be used for manufacturing components of micro turbomachinery, thereby reducing production time and costs. This article discusses the criteria for the selection of plastics suitable for a particular machine, namely micro turbogenerator operating in the organic Rankine cycle (ORC). In addition to the initial selection of materials based on their chemical and physical properties, strength calculations of selected turbogenerator subassemblies were carried out. The obtained results confirmed that some plastics can replace traditional materials used in the manufacture of ORC turbogenerators. This concerns, in particular, the components of the microturbine blade system. After the manufacture of a trial series of such components, it became apparent that, with appropriately chosen plastics, it is possible to shorten the machining time and reduce production costs, all while maintaining the required dimensional tolerances. The results obtained so far prove that it is possible to use plastics to produce components of modern turbomachines, for instance, parts of high-speed microturbines that have to withstand high operating temperatures.

References [1] Ainley, D. G., Mathieson, G. C. R., A Method of Performance Estimation for Axial-Flow Turbines , Tech. rept. Aeronautical Research Council, London 1951. [2] Craig, H. B. M., Cox, H. J. Α., Performance estimation of axial flow turbines , Proc. Inst. Mech. Engrs., 71, Vol. 185 32/71, 1970. [3] Craig, H. R. M., Cox, H. J. A., Performance estimation of axial flow turbines , Proc. Inst. Mech. Eng., 185, 32/71, 407-424, 1971. [4] Denton, J. D., Loss mechanisms in turbomachines , Trans. ASME J. Turbomachinery, 115, 621-656, 1993. [5] Denton, J. D

References [1] Ainley, D. G, Mathieson, G. C. R., A Method of Performance Estimation for Axial Flow Turbines , British Aeronautical Research Council, R&M 2974, 1951. [2] Balicki, W., Chachurski, R., Głowacki, P., Godzimirski, J., Kawalec, K., Kozakiewicz, A., Pągowski, Z., Rowiński, A., Szczeciński, J., Szczeciński S., Lotnicze silniki turbinowe. Konstrukcja – eksploatacja-diagnostyka − Część 1 , Biblioteka Naukowa Instytutu Lotnictwa Nr 30, Warszawa 2010. [3] Bindon, J. P., The measurement and Formation of Tip Clearance Loss. ASME, Journal of Turbomachinery

or turbomachinery expanders are used to recover the energy, and/or the compressed air is used directly in the prime mover. The energy recovery from the stored fluid must contend with a negative pressure and temperature gradient as the storage medium exits the fixed volume storage reservoir. Thus, reheating of the medium and some means of flow and/or pressure control is essential to enable the expander to operate most efficiently and with the optimum high specific enthalpy change. In order to preserve or increase the overall efficiency of the energy storage system

Abstract

Blade Tip Timing (BTT) is a non-intrusive method to measure blade vibration in turbomachinery. Time of Arrival (TOA) is recorded when a blade is passing a stationary sensor. The measurement data, in form of undersampled (aliased) tip-deflection signal, are difficult to analyze with standard signal processing methods like digital filters or Fourier Transform. Several indirect methods are applied to process TOA sequences, such as reconstruction of aliased spectrum and Least-Squares Fitting to harmonic oscillator model. We used standard sine fitting algorithms provided by IEEE-STD-1057 to estimate blade vibration parameters. Blade-tip displacement was simulated in time domain using SDOF model, sampled by stationary sensors and then processed by the sinefit.m toolkit. We evaluated several configurations of different sensor placement, noise level and number of data. Results of the linear sine fitting, performed with the frequency known a priori, were compared with the non-linear ones. Some of non-linear iterations were not convergent. The algorithms and testing results are aimed to be used in analysis of asynchronous blade vibration.

References [1] Grant K. Experimental Testing Of Some Tip-Timing Techniques, 1 st Evi-GTI Conference, Barcelona, 2004. [2] Heath S. Imregun M. An improved single-parameter tip-timing method for turbo-machinery blade vibration measurements using optical laser probes, International Journal of Mechanical Sciences, Vol. 38, №10, 1996, 1047–1058. [3] Heath S. A new technique for identifying synchronous resonances using tip-timing. ASME Journal of Engineering for Gas Turbines and Power. Vol. 122, No. 2. April 2000, 219-225. [4] Heath S. Identification of resonant

Abstract

In the article, a set of deviation angle models, which are used to predict the off-design performance high-pressure turbines, has been presented, basing on a literature study. The deviation angle is a deviation between the actual flow angle and the blade inclination angle. It is an essential parameter in turbine performance evaluation. This angle shall be obtained accurately in 1-D design and evaluation, so as to ensure the validity of blade profiling and calculation results. If deviation angle is ignored, the turbine will produce a lower change of tangential velocity, and consequently a lower torque, output work and enthalpy drop than intended by the designer. For this reason, the deviation angle model needs to be established. There exist a number of different deviation models, resulting in varying degrees of flow deviation when applied. In the article, correlations for gas outlet angle, dependent on the Mach number at outlet and determined by the blade loading towards the trailing edge has been presented. The main difficulty in establishing the deviation model is a continuity in defining the angle for all speed ranges (both subcritical and supercritical). Each of the models presented in the article deals with this problem in a different way. A few deviation models, briefly discussed in the article, are based on experimental data and one is based on analytical approach.

Abstract

Multi-hole probes are simple and robust device to measurement of flow velocity magnitude and direction in wide range of angles of attack – up to 75°. They become popular as they may be easily use to measurement of unknown flow velocity, while optical methods, like PIV or LDA, require some knowledge about the flow for proper setting of measurement devices. Multi-hole probes are also more lasting in comparison with CTA hot-wire probes, which may be damaged by a dust.

A multi-hole probe measures air pressure with one pressure tap on its tip and a few (usually 2, 4, 6 or more) taps on conical or semispherical surface of the probe tip. Based on measured pressures, some non-dimensional pressure coefficients are calculated, which are related to flow velocity direction (i.e. two angles in Cartesian or spherical coordinate system) and magnitude. Finding relations between these parameters is relatively complex, which for years was limiting application of multi-hole probes.

The article summarizes methods of multi-hole probes calibration and use, which may be classified as nulling and non-nulling methods or – with other criteria – as global and local methods. The probe, which was presented in the article, was the 5-hole straight probe manufactured by Vectoflow GmbH and calibrated in the stand designed and manufactured at the Institute of Aviation. The local interpolation algorithm has been used for calibration, with some modifications aimed on mitigate of mounting uncertainty, which is related with the non-alignment of flow velocity direction and probe axis

Results of calibration showed that the accuracy of presented methodology is satisfactory. The standard measurement uncertainty was assessed for 0.2° for the pitch angle and yaw angle, which is better than accuracy declared by the probe’s manufacturer (1.0°). The measurement uncertainty of the flow velocity is approximately 0.12 m/s, similarly like in manufacturer’s data.

References 1. ANSYS Products, Terms & Conditions. ANSYS, Inc. All Rights Reserved, available on: http://www.ansys.com 2. Wróblewski W., Dykas S., Gepert A., 2009, Steam condensing flow modeling in turbine channels, Int. J. Multiphase Flow; Vol. 35(6), pp. 498-506. 3. Yershov S., Rusanov A., 1996, The Application Package FlowER for the Calculation of 3D Viscous Flows Through Multi-Stage Turbomachinery. Certificate of state registration of copyright No. 77, Ukrainian Agency for Copyright and Related Rights, 19.02.1996. 4. Nashchokin V., Semyonov S., 1980

BIBLIOGRAPHY 1. H. Hackenberg, A. Hartung: An approach for estimating the effect of transient sweep through a resonance, in: Proceedings of ASME Turbo Expo 2015: Turbomachinery Technical Conference and Exposition, 2015, pp. 1-11. 2. S. Yeung, R. M. Murray: Reduction of bleed valve rate requirements for control of rotating stall using continuous air injection, IEEE International Conference on Control Applications. 1997, pp.683-690. 3. Y. H. Wu, J. Wu, H. Zhang, W. Chu: Experimental and numerical investigation of near-tip flow field in an axial flow compressor