scholarly journals Feasibility Study of Fluidic Sealing in Turbine Shroud

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3477
Author(s):  
Filip Wasilczuk ◽  
Pawel Flaszynski ◽  
Lukasz Pyclik ◽  
Krzysztof Marugi
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Parametric Study ◽  
Manufacturing Process ◽  
Turbine Blades ◽  
Control Technique ◽  
Leakage Flow ◽  
Streamwise Vortices ◽  
Air Curtain ◽  
Effective Dimensions

This paper analyses the methods for manufacturing turbine blades, focusing on the possibility of manufacturing slots in the region of the shroud. The reason for this analysis is the new flow control technique that can be used to limit the shroud leakage flow in a turbine—the air curtain. The air curtain uses a bypass slot to connect the upstream cavern of a shroud seal with the tip of a shroud fin. The bypass slot is an essential part of the solution, while at the same time introducing difficulties in the manufacturing process. Additionally, a parametric study on the bypass slot dimensions is performed using numerical simulations. The features of the numerical model and its validation against experimental data are presented. The parametric study includes the inlet and outlet dimensions, as well as the width of the slot. The most effective dimensions are shown, along with a possible explanation as to why they are the most effective. Interestingly, a slot that does not cover the whole span of the fin is more effective than a slot covering the whole span of the fin. This is caused by additional streamwise vortices that are created in the proximity of the bypass slot.

Parametric study of slotted diffuser effects on a highly loaded centrifugal compressor

2019 ◽  
Vol 233 (6) ◽  
pp. 702-714
Author(s):  
Yingjie Zhang ◽  
Xingen Lu ◽  
Yanfeng Zhang ◽  
Ge Han ◽  
Junqiang Zhu
Keyword(s):  
Centrifugal Compressor ◽  
Flow Separation ◽  
Parametric Study ◽  
Control Technique ◽  
Leakage Flow ◽  
Suction Surface ◽  
Flow Angle ◽  
Stall Margin ◽  
Compressor Performance ◽  
Highly Loaded

Flow separations in the vaned diffuser play a critical role in the stall margin of centrifugal compressors. To extend the stable operating range of a highly loaded centrifugal compressor, a flow control technique of locating a slot near the vaned diffuser's leading edge is proposed. A parametric study of slot geometry variations, in terms of the slotted portion depth and length, is carried out to summarize the trend of compressor performance and to reveal the corresponding flow physics related to the slot geometries. The design methodology is concluded to provide a guideline for stall margin improvement by the slotted diffuser. Application of a well-designed slotted diffuser shows that the flow separations inside the diffuser passages are suppressed at low flow rates, and the stall margin is increased without performance deterioration. The leakage flow passing through the slotted portion intensifies the passage vortex at the hub/suction surface corner, and decreases the flow angle at the diffuser inlet, leading to the suppression of flow separations on both the suction and pressure surfaces of the diffuser, respectively. However, it is found that the compressor performance deteriorates with increasing slotted portion depth and length, even though the stall margin is increased. When the slot depth is increased by up to 12% of the diffuser vane height, the leakage flow is not able to roll-up into a vortex that has the potential to mitigate the flow separation at the hub/suction surface corner. Instead, it enhances the flow separation region near the suction surface due to the negative effect of leakage flow; eventually, the stage performance is deteriorated. In conclusion, the slot depth should not exceed 9% of the diffuser vane height, and the optimum slot length is no greater than 6%–12% of the diffuser chord length, which provides a basic guideline for slotted diffuser design.

Passive Reduction of Leakage by Transverse Jet

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Filip Wasilczuk ◽  
Paweł Flaszyński ◽  
Piotr Kaczyński ◽  
Ryszard Szwaba ◽  
Piotr Doerffer ◽  
...  
Keyword(s):  
Experimental Data ◽  
Numerical Simulations ◽  
Mass Flow ◽  
Streamwise Vortices ◽  
Bypass Flow ◽  
Air Curtain ◽  
Flow Reduction ◽  
Transverse Jet ◽  
Experimental Researches ◽  
Good Agreement

Abstract This article presents investigations of mass flow reduction in a gap above a fin by the air curtain technique. The proposed method uses slots in the fin to generate a bypass flow and to create a fluidic barrier in the gap above the fin. Both numerical and experimental researches were conducted and the air curtain proved to be effective, showing the mass flow reduction up to about 20%. The comparison of numerical simulations and experimental data showed good agreement, and the flow structure details were analyzed based on the numerical results. The analysis shows that the blown air in the gap leads to creation of streamwise vortices. They enforce crosswise nonuniformity of the flow velocity in the gap and downstream, what finally influences on higher dissipation effects and mass flow reduction in the gap.

scholarly journals Investigation of the Thickness Differential on the Formability of Aluminum Tailor Welded Blanks

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 875
Author(s):  
Jie Wu ◽  
Yuri Hovanski ◽  
Michael Miles
Keyword(s):  
Experimental Data ◽  
Finite Element ◽  
Numerical Model ◽  
Plastic Strain ◽  
Finite Element Model ◽  
Equivalent Plastic Strain ◽  
Element Model ◽  
Dome Height ◽  
Tailor Welded Blanks ◽  
Simulation Results

A finite element model is proposed to investigate the effect of thickness differential on Limiting Dome Height (LDH) testing of aluminum tailor-welded blanks. The numerical model is validated via comparison of the equivalent plastic strain and displacement distribution between the simulation results and the experimental data. The normalized equivalent plastic strain and normalized LDH values are proposed as a means of quantifying the influence of thickness differential for a variety of different ratios. Increasing thickness differential was found to decrease the normalized equivalent plastic strain and normalized LDH values, this providing an evaluation of blank formability.

scholarly journals Combining the Anticancer and Immunomodulatory Effects of Astragalus and Shiitake as an Integrated Therapeutic Approach

Nutrients ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 2564
Author(s):  
Biju Balakrishnan ◽  
Qi Liang ◽  
Kevin Fenix ◽  
Bunu Tamang ◽  
Ehud Hauben ◽  
...  
Keyword(s):  
Experimental Data ◽  
Manufacturing Process ◽  
Therapeutic Potential ◽  
Lentinus Edodes ◽  
Immunomodulatory Effects ◽  
Shiitake Mushrooms ◽  
Medicinal Foods ◽  
Medicinal Food ◽  
Immunogenic Properties ◽  
Prevention Approach

Astragalus root (Huang Qi) and Shiitake mushrooms (Lentinus edodes) are both considered medicinal foods and are frequently used in traditional Chinese medicine due to their anticancer and immunomodulating properties. Here, the scientific literatures describing evidence for the anticancer and immunogenic properties of Shiitake and Astragalus were reviewed. Based on our experimental data, the potential to develop medicinal food with combined bioactivities was assessed using Shiitake mushrooms grown over Astragalus beds in a proprietary manufacturing process, as a novel cancer prevention approach. Notably, our data suggest that this new manufacturing process can result in transfer and increased bioavailability of Astragalus polysaccharides with therapeutic potential into edible Shiitake. Further research efforts are required to validate the therapeutic potential of this new Hengshan Astragalus Shiitake medicinal food.

Validating Numerical CFD Simulations With Experimental Data for Turbulence Phenomena in Axial Flow Gas Turbine Diffusers

2009 ◽  
Author(s):  
Farrokh Zarifi-Rad ◽  
Hamid Vajihollahi ◽  
James O’Brien
Keyword(s):  
Experimental Data ◽  
Gas Turbine ◽  
Turbine Blades ◽  
Axial Flow ◽  
Experimental Results ◽  
Scale Model ◽  
Data Set ◽  
Pressure Profiles ◽  
Scale Models ◽  
Inlet Conditions

Scale models give engineers an excellent understanding of the aerodynamic behavior behind their design; nevertheless, scale models are time consuming and expensive. Therefore computer simulations such as Computational Fluid Dynamics (CFD) are an excellent alternative to scale models. One must ask the question, how close are the CFD results to the actual fluid behavior of the scale model? In order to answer this question the engineering team investigated the performance of a large industrial Gas Turbine (GT) exhaust diffuser scale model with performance predicted by commercially available CFD software. The experimental results were obtained from a 1:12 scale model of a GT exhaust diffuser with a fixed row of blades to simulate the swirl generated by the last row of turbine blades five blade configurations. This work is to validate the effect of the turbulent inlet conditions on an axial diffuser, both on the experimental front and on the numerical analysis approach. The object of this work is to bring forward a better understanding of velocity and static pressure profiles along the gas turbine diffusers and to provide an accurate experimental data set to validate the CFD prediction. For the CFD aspect, ANSYS CFX software was chosen as the solver. Two different types of mesh (hexagonal and tetrahedral) will be compared to the experimental results. It is understood that hexagonal (HEX) meshes are more time consuming and more computationally demanding, they are less prone to mesh sensitivity and have the tendancy to converge at a faster rate than the tetrahedral (TET) mesh. It was found that the HEX mesh was able to generate more consistent results and had less error than TET mesh.

Development of the Tip-Leakage Flow Downstream of a Planar Cascade of Turbine Blades: Vorticity Field

1989 ◽  
Author(s):  
M. Yaras ◽  
S. A. Sjolander
Keyword(s):  
Simple Model ◽  
Turbine Blades ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Vorticity Field ◽  
Trailing Edge ◽  
Tip Leakage ◽  
Blade Row ◽  
Axisymmetric Structure ◽  
Insight Into

The paper presents detailed measurements of the tip-leakage flow emerging from a planar cascade of turbine blades. Four clearances of from 1.5 to 5.5 percent of the blade chord are considered. Measurements were made at the trailing edge plane, and at two main planes 1.0 and 1.56 axial chord lengths downstream of the cascade. The results give insight into several aspects of the leakage flow including: the size and strength of the leakage vortex in relation to the size of the tip gap and the bound circulation of the blade; and the evolution of the components of vorticity as the vortex diffuses laterally downstream of the blade row. The vortex was found to have largely completed its roll-up into a nearly axisymmetric structure even at the trailing edge of the cascade. As a result, it was found that the vortex could be modelled surprisingly well with a simple model based on the diffusion of a line vortex.

Analysis of Blunt Trailing Edge Airfoils

2003 ◽  
Author(s):  
K. J. Standish ◽  
C. P. van Dam
Keyword(s):  
Experimental Data ◽  
Wind Turbine ◽  
Turbine Blades ◽  
Navier Stokes ◽  
Computational Techniques ◽  
Wind Turbine Blades ◽  
Trailing Edge ◽  
Blunt Trailing Edge ◽  
Large Wind ◽  
Structural Volume

The adoption of blunt trailing edge airfoils for the inner regions of large wind turbine blades has been proposed. Blunt trailing edge airfoils would not only provide increased structural volume, but have also been found to improve the lift characteristics of airfoils and therefore allow for section shapes with a greater maximum thickness. Limited experimental data makes it difficult for wind turbine designers to consider and conduct tradeoff studies using these section shapes. This lack of experimental data precipitated the present analysis of blunt trailing edge airfoils using computational fluid dynamics. Several computational techniques are applied including a viscous/inviscid interaction method and several Reynolds-averaged Navier-Stokes methods.

Leakage Flow Investigations on a Through-Wall Crack Related to Thermal Fatigue of Nuclear Power Plant Piping

2017 ◽  
Author(s):  
Stefan Schmid ◽  
Rudi Kulenovic ◽  
Eckart Laurien
Keyword(s):  
Experimental Data ◽  
Nuclear Power ◽  
Numerical Models ◽  
Measurement Techniques ◽  
Experimental Investigations ◽  
Leakage Flow ◽  
Test Rig ◽  
Reduced Pressure ◽  
Flow Rates ◽  
Set Up

For the validation of empirical models to calculate leakage flow rates in through-wall cracks of piping, reliable experimental data are essential. In this context, the Leakage Flow (LF) test rig was built up at the IKE for measurements of leakage flow rates with reduced pressure (maximum 1 MPA) and temperature (maximum 170 °C) compared to real plant conditions. The design of the test rig enables experimental investigations of through-wall cracks with different geometries and orientations by means of circular blank sheets with integrated cracks which are installed in the tubular test section of the test rig. In the paper, the experimental LF set-up and used measurement techniques are explained in detail. Furthermore, first leakage flow measurement results for one through-wall crack geometry and different imposed fluid pressures at ambient temperature conditions are presented and discussed. As an additional aspect the experimental data are used for the determination of the flow resistance of the investigated leak channel. Finally, the experimental results are compared with numerical results of WinLeck calculations to prove specifically in WinLeck implemented numerical models.

Research Regarding the Effects of 120 mm HE Mortar Bombs on Advanced Materials

2021 ◽  
Vol 42 ◽  
pp. 128-134
Author(s):  
Daniela Pintilie ◽  
Iuliana Florina Pană ◽  
Adrian Malciu ◽  
Constantin Puică ◽  
Cristina Pupăză
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Initial Velocity ◽  
High Explosive ◽  
Numerical Approach ◽  
Advanced Materials ◽  
Physical Mechanisms ◽  
Shock Wave Generation ◽  
3D Numerical Model ◽  
Experimental Trials

High Explosive Mortar bombs are used on the battlefield for destroying the manpower, non-armoured equipment and shelters. The paper describes an original experimental and numerical approach regarding the potential threats caused by the detonation of 120 mm HE mortar bombs. The evaluation of the bomb effect presumes the fulfillment of experimental trials that focus on two physical mechanisms which appear after the detonation of the cased high explosive. These mechanisms are the shock wave generation and the fragments propulsion, which were also studied by a numerical model that provides results over the bomb fragmentation mode. The novelty of the paper consists in the calibrated 3D numerical model confirmed by the experimental data, which provides information over the fragmentation process of the case and the initial velocity of its fragments, proving that the main threat of this type of ammunition is the effect through metal fragments. The results of numerical simulation and experimental data are used for their comparative analysis and the assessment of the phenomena.

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