Droplet Generation by Disintegration of Oil Films at the Rim of a Rotating Disk

ABSTRACT A fundamental study has been performed to examine oil film disintegration mechanisms at the rim of a rotating disk. The configuration investigated is an abstraction of one of the droplet generation sources in an aero-engine bearing compartment. The paper aims to contribute to both the determination of directly applicable droplet characteristics and the establishment of a data-base that can be used for the development of droplet generation models. The near-term objectives of the study are (i) to identify disintegration modes relevant with respect to aeroengine bearing compartment operating conditions, (ii) to determine droplet sizes under those operating conditions, and (iii) to measure individual droplet diameter/velocity relationships. The long-term objective is to incorporate this information into advanced CFD-based design tools. The disintegration modes identified here were similar to previously reported flow regimes generated by rotary atomizer

EMISSION AND PERFORMANCE OF A LEAN-PREMIXED GAS FUEL INJECTION SYSTEM FOR AERODERIVATIVE GAS TURBINE ENGINES

ABSTRACT A dry-low-NOx, high-aimow-capacity fuel injection system for a leanpremixed combustor has been developed for a moderate pressure ratio (20:l) aeroderivative gas turbine engine. Engine requirements for cornbustor pressure drop, emissions, and operability have been met. Combustion performance was evaluated at high power conditions in a high-pressure, single-nozzle test facility which operates at full baseload conditions. Single digit NOx levels and high combustion efficiency were achieved A wide operability range with no signs of flashback, autoignition. or thermal problems was demonsuated. NOx sensitivities 10 pressure and residence time were found to be small at flame temperatures below 1850 K (2870 D. Above 1850 K some NOx sensitivity to pressure and residence Lime was observed and was associated with the increased role of the thermal NOx production mechanism at elevated flame temperatures

Measurements in a Turbine Cascade over a Contoured Endwall: Discrete Hole Injection of Bleed Flow,”

ABSTRACT Thermal and flow field measurements taken within a cascade passage are presented. The cascade has two passages between three airfoils and two endwalls, one flat and one contoured. Measurements were done on and near the contoured endwall. The main objective is to document the effectiveness of cooling the contoured endwall with bleed flow that emerges through two rows of staggered, discrete holes on the contoured endwall, upstream of the airfoils. Similar studies have been performed in our lab with bleed flow emerging from slots upstream of the same contoured endwall. Both those and the present studies are with high free stream turbulence intensity, TI ~ 9%, of the approach flow. This is characteristic of the approach flow to first stage vanes in most operating engines. In the experiments, the bleed flow is heated slightly above the main stream flow and downstream temperature fields are documented. Three bleed flow rates are tested. It is shown that at a lower flow rate (1.5% of the core flow) the cascade endwall cross-flow carries coolant towards the suction side. However, as the coolant rate is increased, the coolant attains sufficient momentum that no suction-side coolant migration is seen. Velocity measurements taken with triple-sensor, hot-wire anemometry document migration of the bleed flow by way of showing regions of stronger shear, and help describe mixing of the passage flow with the bleed flow. At higher coolant flow rates, strong blockage and mixing effects become evident

Design and Development of a Research Combustor for Lean Blow-Out Studies

In a modern aircraft gas turbine combustor, the phenomenon of lean blow-ou

THE FLOW FIELD AND MAIN GAS INGESTION IN A ROTOR-STATOR CAVITY Proceedings of GT2007 ASME Turbo Expo 2007: Power for Land, Sea and Air

ABSTRACT The ingestion of mainstream gas into turbine rotor-stator disk cavities and simultaneously, the egress of cavity gas into the main gas path are consequences of the prevailing unsteady, three-dimensional flow field. To understand these processes, we are carrying out a study that combines experiments in a model single-stage axial turbine with computational fluid dynamic (CFD) simulations. The turbine stage features vanes, blades, and axially overlapping radial clearance rim seal. In this paper, we present time-resolved velocity maps, obtained by particle image velocimetry, of the flow in the disk cavity at four experimental conditions as defined by the main air flow rate, rotor speed, and purge air flow rate. Time-averaged but spatially local measurement of main air ingestion is also presented. Significant ingestion occurred at two of the four experimental conditions where the purge air flow rate was lowit is found that high tangential (swirl) velocity fluid intersperses with lower tangential velocity fluid in the rim region of the cavity. It is argued that the high tangential velocity fluid is comprised of the ingested main air, while the lower tangential velocity fluid is the indigenous cavity air. This interpretation is corroborated by the results of the unsteady, three-dimensional CFD simulation. When the purge flow rate was high, no ingestion occurred as expected; also, large-scale structures that were unsteady appeared in the cavity flow giving rise to large velocity fluctuations. It is necessary to obtain time-resolved information from experiments and computation in such a flow because even when the vane-blade relative position is matched during a particular experiment, the instantaneous flow field does not necessarily remain the same. As such, some of the flow patterns will be smeared out if the interrogation time scale is large. NOMENCLATURE b outer radius of disk cavity