This paper presents experimental data and an associated correlation for the windage resulting from a disc rotating in air, characteristic of gas turbine engines and relevant to some electrical machine applications. A test rig has been developed which uses an electric motor to drive a smooth bladeless rotor inside an enclosed pressurised housing. The rig has the capability of reaching rotational and throughflow Reynolds numbers representative of a modern gas turbine.A moment coefficient has been used to allow a non-dimensional windage torque parameter to be calculated and agreement with the relevant data in the literature has been found within 10 %. Infrared measurements have been performed which allow direct surface temperatures of the rotating disc to be obtained. Laser Doppler Anemometry measurements have been made which allow velocities in the flow field of the rotor-stator cavity to be examined and tangential velocities corresponding to rotationally and to radially dominated flow conditions are shown.The importance of the flow regime in relation to the resulting windage has been identified and in particular it is noted that windage is a function not only of the ratio of rotational and radial flow dominance as defined by the turbulence parameter, but also, for a given value of the turbulence parameter, the magnitude of the rotationally induced and superimposed flows. The Coren, D., Childs, P.R.N., and Long, C.A> Windage sources in smooth-walled rotating disc systems in Proceedings of the Institution of Mechanical Engineers Part C -Journal of Mechanical Engineering Science, 223(4), 2009 DOI: 10.1243/09544062JMES1260. 2 experiments extend the range of data available for windage in rotor-stator systems and has been used to produce a correlation suitable for applications operating up to the range Re = 10 7 .
Gas turbine engine performance requires effective and reliable internal cooling over the duty cycle of the engine. Life predictions for rotating components subject to the main gas path temperatures are vital. This demands increased precision in the specification of the internal air system flows which provide turbine stator well cooling and sealing. This in turn requires detailed knowledge of the flow rates through rim seals and interstage labyrinth seals. Knowledge of seal movement and clearances at operating temperatures is of great importance when prescribing these flows. A test facility has been developed at the University of Sussex, incorporating a two stage turbine rated at 400 kW with an individual stage pressure ratio of 1.7:1. The mechanical design of the test facility allows internal cooling geometry to be rapidly reconfigured, while cooling flow rates of between 0.71 Cw, ENT (>nd 1.46 C^^ ENT, inay be set to allow ingress or egress dominated cavity flows. The main annulus and cavity conditions correspond to in cavity rotational Reynolds numbers of 1.71 x 10^< Reip<1.93 x 70*. Displacement sensors have been used to establish hot running seal clearances over a range of stator well flow conditions, allowing realistic flow rates to be calculated. Additionally, gas seeding techniques have been developed, where stator well and main annulus flow interactions are evaluated by measuring changes in gas concentration. Experiments have been performed which allow rim seal and re-ingestion flows to be quantified. It will be shown that this work develops the measurement of stator well cooling flows and provides data suitable for the validation of improved thermo-mechanical and CFD codes, beneficial to the engine design process.
This paper presents a parametric Finite Element model of road bicycle frames using beam elements with varying tube profiles. A range of existing frame geometries were subject to various in plane and out of plane loading conditions to examine the influence of tube profiles (as published by the Reynolds, Columbus and Tange manufacturers) on the lateral stiffness and vertical compliance of the frames. This was an extension of previous work which characterised the influence of overall frame geometries (tube lengths and angles) on the stiffness characteristics of frames. For a subset range of frame sizes (with seat tube lengths varying from 490-630mm), parameters were used to define dimensions for circular tube profile shapes, varying wall thicknesses associated with butted tubes. In this paper only steel tubing was considered in order to isolate and focus in detail on the influence of the tube profile geometries on the stiffness characteristics of the frames for a single material. Further work is required to validate this model using a frame stiffness jig and to characterise the influence of material choice on the stiffness and strength characteristics for steel, aluminium and titanium frames using commercially available tubesets and their published stiffness and strength values.
Optimisation of cooling systems within gas turbine engines is of great interest to engine manufacturers seeking gains in performance, efficiency and component life. The effectiveness of coolant delivery is governed by complex flows within the stator wells and the interaction of main annulus and cooling air in the vicinity of the rim seals. This paper reports the development of a test facility which allows the interaction of cooling air and main gas paths to be measured at conditions representative of those found in modern gas turbine engines. The test facility features a two stage turbine with an overall pressure ratio of approximately 2.6:1. Hot air is supplied to the main annulus using a Rolls-Royce Dart compressor driven by an aero-derivative engine plant. Cooling air can be delivered to the stator wells at multiple locations and at a range of flow rates which cover bulk ingestion through to bulk egress. The facility has been designed with adaptable geometry to enable rapid changes of cooling air path configuration. The coolant delivery system allows swift and accurate changes to the flow settings such that thermal transients may be performed. Particular attention has been focused on obtaining high accuracy data, using a radio telemetry system, as well as thorough through-calibration practices. Temperature measurements can now be made on both rotating and stationary discs with a long term uncertainty in the region of 0.3 K. A gas concentration measurement system has also been developed to obtain direct measurement of re-ingestion and rim seal exchange flows. High resolution displacement sensors have been installed in order to measure hot running geometry. This paper documents the commissioning of a test facility which is unique in terms of rapid configuration changes, non-dimensional engine matching and the instrumentation density and resolution. Example data for each of the measurement systems is presented. This includes the effect of coolant flow rate on the metal temperatures within the upstream cavity of the turbine stator well, the axial displacement of the rotor assembly during a commissioning test, and the effect of coolant flow rate on mixing in the downstream cavity of the stator well.
Market competitiveness for aero engine power plant dictates that improvements in engine performance and reliability are guaranteed a priori by manufacturers. The requirement to accurately predict the life of engine components makes exacting demands of the internal air system, which must provide effective cooling over the engine duty cycle with the minimum consumption of compressor section air. Tests have been conducted at the University of Sussex using a turbine test facility which comprises a two stage turbine with an individual stage pressure ratio of 1.7:1. Main annulus air is supplied by an adapted Rolls-Royce Dart compressor at up to 440 K and 4.8 kg s−1. Cooling flow rates ranging from 0.71 to 1.46 Cw, ent, a disc entrainment parameter, have been used to allow ingress or egress dominated stator well flow conditions. The mechanical design of the test section allows internal cooling geometry to be rapidly re-configured, allowing the effect of jet momentum and coolant trajectory to be investigated. An important facet to this investigation is the use of CFD to model and analyse the flow structures associated with the cavity conditions tested, as well as to inform the design of cooling path geometry. This paper reports on the effectiveness of stator well coolant flow rate and delivery configurations using experimental data and also CFD analysis to better quantify the effect of stator well flow distribution on component temperatures.
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