TASK Quarterly   Scientific Bulletin of the Centre of Informatics - Tricity Academic Supercomputer & networK   ISSN 1428-6394

Volume 19, Number 2, 2015


Contents:



Abstracts:

  • Filip Wasilczuk, Paweł Flaszyński and Piotr Doerffer Numerical Simulations of Gap Flow above Rotating Disk

    A rotating disk can be considered a basic configuration for the investigations of the impact of various conditions on the flow through the clearance between the shrouded turbine blade and the casing. Numerical calculations using Fine/Turbo Numeca were conducted to examine the influence of the rotational velocity and the pressure difference across the disk on the flow conditions, especially the mass flow through the clearance. The results were validated using the experimental data. Moreover, the flow field was investigated to reveal the vortices induced in the flow. The calculations showed a significant drop of the mass flow with a rise of the rotation velocity. Additionally, the vortex created upstream of the disk at higher rotation velocities was observed. The phenomenon of separation at the edge of the disk was investigated.

  • Piotr Kaczyński, Ryszard Szwaba, Bartosz Puchowski, Piotr Doerffer and Paweł Flaszyński Aerodynamic Enhancement in Inner Channel of Turbine Blade

    This paper presents the numerical and experimental study of the flow structure in a radial cooling passage model of a gas turbine blade. The investigations focus on the flow aerodynamics in the channel, which is an accurate representation of the configuration used in aero engines. The flow structure and pressure drop were measured by classical measurement techniques. The stagnation pressure and velocity measurements in a channel outlet plane were performed. The investigations concerning the flow field and heat transfer used in the design of radial cooling passages are often developed from simplified models. It is important to note that real engine passages do not have perfect rectangular cross sections, but include corner fillets, ribs with fillet radii and special orientation. Therefore, this work provides detailed fluid flow data for a model of radial cooling geometry which possesses very realistic features. The main purpose of these investigations was to study different channel configurations and their influence on the flow structure and pressure losses in a radial cooling passage of a gas turbine blade.

  • Marcin Kurowski and Piotr Doerffer Influence of Membrane Amplitude and Forcing Frequency on Synthetic Jet Velocity

    This paper presents the results of numerical investigations of a synthetic jet actuator for an active flow control system. The Moving-Deforming-Mesh method as a boundary condition is used to capture the real physical phenomenon. This approach allows precise investigation of the influence of the membrane amplitude, the forcing frequency and cavity effect on the jet velocity. A synthetic jet actuator is simulated using a membrane perpendicular to the surface arrangement. Two cases are investigated to maximize the jet velocity – an actuator with one and two membranes in a cavity. Two main forcing frequencies can be specified in the synthetic jet actuator application. One corresponds to the diaphragm natural frequency and the other corresponds to the cavity resonant frequency (the Helmholtz frequency). This study presents the results of actuators operating at the two abovementioned forcing frequencies. The simulation results show an increase in the jet velocity as a result of an increase in the membrane peak-topeak displacement. This study was a preliminary study of the synthetic jet actuator for single and double membrane systems. The optimization process of the synthetic jet actuator geometry and parameters is ongoing. Numerical results obtained in these investigations are to be validated in the experimental campaign.

  • Tomasz Lewandowski and Piotr Doerffer Hole Extension Effect on Transpiration Flow Efficiency

    The present analysis of the hole extension effect on the transpiration flow effiiency is a part of the research [1] which aims at defining a physical transpiration model of the flow through perforated plates. Perforated walls find a wide use as a method of flow control and efusive cooling. Some data on the L/D (hole length to diameter ratio) effect on the flow structure and mass flow rate may be found in the literature [2, 3], but all those works concern holes of a diameter at least one order of magnitude larger than those used in the simulations presented in this paper. Due to the size of the analyzed holes and their cylindrical shape, the only method of analysing the flow through such holes is the numerical method. In the conducted simulations, the holes were D = 0.6 mm, 0.3 mm and 0.125 mm in diameter and the perforation values were equal to 4%, 5%, 8% and 10%. The L/D ratio was changed between 0.25 and 8. The data bank of the flow through the cylindrical holes was produced. The hole extension has a significant influence on the obtained mass flow rate and, consequently, on the transpiration flow effiiency. In addition, entrance effects appear to be important.

  • Javier Martinez, Piotr Doerffer, Oskar Szulc and Fernando Tejero Aerodynamic Analysis of Wind Turbine Rotor Blades

    One of the main achievements of the PLGrid Plus project is the implementation of new tools and services designed for the numerical prediction of the aerodynamic performance of wind energy turbines. An innovative and unique integration tool (Aero-T) is aiming at automating all stages (pre-, solution and post-processing) of the numerical simulation of the flow around wind turbine rotor blades using commercial CFD software based on the RANS approach and block-structured computational grids. The FINE/Turbo package (Numeca Int.) is applied in the structured grid generation process and solution phases, while the analysis of results is left to the Tecplot 360 (Tecplot Inc.) software. A demonstrator based on the NREL Phase VI rotor experiment (conducted at NASA Ames) is introduced to prove the excellent prediction capabilities of Aero-T.

  • Michał Piotrowicz, Paweł Flaszyński and Ryszard Szwaba Influence of Limiting Walls on Shock Wave Structure in Single Passage Test Section with Compressor Profile

    The shock wave boundary layer interaction on the suction side of a transonic compressor blade is one of the main objectives of the TFAST project (Transition Location Effect on Shock Wave Boundary Layer Interaction). In order to look more closely into the flow structure on the suction side of the blade, a design of a turbine passage model in a rectilinear transonic wind tunnel was proposed. The model which could reproduce the flow structure, the shock wave location, the pressure distribution and the boundary layer development similar to the obtained in a reference cascade profile is the main objective of the design presented here. The design of the proposed test section is very challenging, because of the existence of a shock wave, its interaction with the boundary layer and its influence on the 3-D flow structure in the test section. The paper presents the influence of the test section geometry configuration on the flow structure as an effect of the shock wave boundary layer interaction.

  • Ryszard Szwaba, Paweł Flaszyński, Jan Artur Szumski and Piotr Doerffer Influence of Air Cooling and Air-Jet Vortex Generator on Flow Structure in Turbine Passage

    The paper concerns the experimental investigations and numerical simulations of a high loaded model of a turbine blade. An increase in the blade load leads to enlargement of a local supersonic zone terminated by a shock wave on the suction side. The Mach number upstream of the shock reaches up to 1.6. The interaction of the shock wave with a boundary layer at such a high Mach number leads to a strong separation. Streamwise vortices generated by air-jets were used for the interaction control. The work presents the experimental and numerical results of the application of an air-jets vortex generator on the suction side of cooled turbine blades. Very interesting results were obtained in the context of the air cooling and air-jet vortex generator influence on the flow structure in the turbine passage.

  • Fernando Tejero, Piotr Doerffer and Oskar Szulc Shock Wave Induced Flow Separation Control by Air-Jet and Rod Vortex Generators

    Flow separation control by Vortex Generators (VGs) has been analyzed over the last decades. The majority of the research concerning this technology has been focused on subsonic flows where its effectiveness for separation reduction has been proven. Less complex configurations should be analyzed as a first step to apply VGs in transonic conditions, commonly present in many aviation applications. Therefore, the numerical investigation was carried out for a Shock Wave-Boundary-Layer Interaction (SWBLI) phenomenon inducing strong flow separation at the suction side of the NACA 0012 profile. For this purpose, two kinds of VGs were analyzed: well documented Air-Jet Vortex Generators (AJVGs) and our own invention of Rod Vortex Generators (RVGs). The results of the numerical simulations based on the RANS approach reveal a large potential of this passive flow control system in delaying stall and limiting separation induced by a strong, normal shock wave terminating a local supersonic area.

  • Oskar Szulc, Piotr Doerffer, Fernando Tejero, Jerzy Żółtak and Jacek Małecki Numerical Analysis of High-Speed Impulsive (HSI) Noise of PZL W3-A “Sokół” (Falcon) Helicopter Main Rotor in Forward Flight

    The paper presents the results of a numerical simulation of the flow and acoustic field generated by the PZL W3-A “Sokół” (Falcon) helicopter main rotor in high-speed forward flight conditions based on the URANS approach and the chimera overlapping grids technique. A refined CFD model (40+ million of control volumes, 600+ blocks chimera mesh) was designed to resolve the flow-field together with the low-frequency content of the acoustic pressure spectrum in the near-field of the rotor blades to allow high-speed impulsive (HSI) noise prediction. Detailed 3D data was recorded for one rotor revolution (approx. 3 TB) allowing exceptional insight into the physical mechanisms initiating the occurrence and development of the HSI noise phenomenon.

  • Janusz Telega, Piotr Doerffer, Ryszard Szwaba and Piotr Kaczyński Parallelized Numerical Code for Derivation of Heat Transfer Coefficient from Experimental Data

    An application of parallel computation capabilities in the MATLAB language for the analysis of experimental data concerning the heat transfer coeffiient on ribbed walls is presented in this paper. A description of the experimental study, mathematical model and numerical implementation is also given. The obtained results of measurements and calculations shown here clearly indicate the influence of ribbed walls on the heat transfer coeffiient distribution in an internal, subsonic flow.

  • Helena Nowakowska, Marcin Lackowski, Tomasz Ochrymiuk and Ryszard Szwaba Novel Electrostatic Wind Energy Converter: an Overview

    The article discusses the historical development and embodiments of the concept of generating electricity from wind energy without the use of wind turbines, so called electrostatic bladeless generators or generators without moving parts. A simplified theory and the principles of operation of generators that use a motion of charged particles in an electric field occurring under the drag force of the wind are described. Two contemporary solutions utilising the principle that has reached an implementation stage, EWICON and AerovoltaicTM, are presented in detail.