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Influence of Cavity Leakage flow on Corner Separation in a Shrouded Stator Cascade

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Journal of Thermal Science 2023年第1期32卷 351-365页

作者： KONG Xiaozhi HUANG Tianshuo LIU Yuxin LU Huawei WANG Long Naval Architecture and Ocean Engineering College Dalian Maritime UniversityDalian 116026China Marine Engineering College Dalian Maritime UniversityDalian 116026China

The impacts of the cavity leakage flow on the shrouded stator aerodynamic performance were investigated by modelling the annular cascade mainstream with the seal cavity flow path based on the validated numerical ***,the interactions between the cavity leakage and the mainstream were also determined in the current *** development of hub corner separation under the action of leakage was discussed and the total pressure loss coefficient as well as the entropy-based loss coefficient was employed to evaluate the performance changes at different seal clearances and cavity rotational *** results show that the cavity leakage flow induces a new vortex near the blade leading edge and plays an important role in the development of passage vortex and the size of concentrated shedding *** increasing the seal clearance with more cavity leakage flow rate,an increase in the pitchwise extent of the separation region under 15%span is significant and the total pressure loss in the separation core *** addition,with the increase of cavity rotating speed,the starting point of corner separation moves backward,reducing the size and depth of the hub corner *** mainstream loss reduction in combination with the entropy increase in the seal cavity causes the entropy-based loss coefficient to perform a trend of decreasing first and then increasing with the cavity speed.

关键词： shrouded stator cavity leakage flow corner separation loss coefficient

Pneumatic Measurements Downstream of a Radial Turbine Nozzle Cascade

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Journal of Thermal Science 2010年第1期19卷 42-46页

作者： Martin LUXA Rudolf DVORAK David SIMURDA Jan VIMMR Department of Fluid Dynamics Institute of Thermomechanicsv.v.i.Academy of Science of the Czech RepublicPragueCzech Republic Department of Mechanics University of West Bohemia in PilsenPlzeňCzech Republic

This paper deals mainly with pneumatic measurements on a radial turbine nozzle cascade. The fill radial cascade guarantees the exit flow field periodicity downstream of it. A special traversing mechanism with a five - hole conical probe moving along a circular path behind the cascade was used for flow field investigation in this type of cascade with very low aspect ratio. The analyses of results of 2D and 3D pneumatic measurements including loss coefficient values are presented.

关键词： radial turbine cascade aspect ratio pneumatic measurement loss coefficient

Investigation of pressure drop in flexible ventilation ducts under different compression ratios and bending angles

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Building Simulation 2021年第4期14卷 1251-1261页

作者： Ho Kam Dai Wenjie Huang Liye Fu Chao-Hsin Lin Daniel Wei Zhongzhe Dong Ruoyu You Chun Chen Department of Mechanical and Automation Engineering The Chinese University of Hong KongShatinN.T.999077Hong KongChina Department of Building Services Engineering The Hong Kong Polytechnic UniversityKowloon999077Hong KongChina Environmental Control Systems Boeing Commercial AirplanesEverettWA98203USA Boeing Research&Technology Beijing100027China Shenzhen Research Institute The Chinese University of Hong KongShenzhen518057China

Due to the large degree of freedom in terms of design and installation, flexible ventilation ducts are commonly used in ventilation systems. However, excessive use of flexible ducts may lead to greater pressure drop and higher energy consumption. This study conducted experimental measurements to characterize the pressure drop in flexible ventilation ducts with different compression ratios and bending angles. This investigation first measured the pressure drop in straight flexible ducts with four compression ratios under various airflow rates. The calculated friction factor for the straight flexible ducts was negatively associated with the compression ratio. Next, the pressure drops in single-bend flexible ducts with various bending angles from 30° to 150° were measured under various airflow rates. The calculated loss coefficient of the bend increased with the bending angle for single-bend flexible ducts. Finally, the influence of the intermediate duct length on the pressure drop across two bends was experimentally investigated. When the length of the intermediate duct was greater than eight times the inner diameter, the pressure drop across a double-bend flexible duct could be calculated from the friction factors and loss coefficients with a relative error less than 1%. The data obtained in this study can be used to calculate the total pressure loss in flexible ventilation ducting systems in buildings.

关键词： ventilation pressure loss flex duct fan energy friction factor loss coefficient

Numerical study of camber and stagger angle effects on the aerodynamic performance of tandem-blade cascades

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Propulsion and Power Research 2018年第1期7卷 30-42页

作者： Behshad Ghazanfari Mahdi Nili-Ahmadabadi Ashkan Torabi-Farsani Mohammad Hossein Noorsalehi Department of Mechanical Engineering Isfahan University of TechnologyIsfahan ***Iran

Jet engine manufacturers and designers are seeking for lighter and smaller type of axial *** the aerodynamic characteristics of blades is carried out by controlling the boundary *** way to control the boundary layer is using tandem ***-blade cascades are capable of using highly loaded stages for axial compressors because they provide more works than single-blade *** other words,tandem blades help to achieve a specified total pressure ratio with less number of ***,one of the most important problems for researchers is to optimize the aerodynamic parameters of tandem *** the geometrical parameters of blades is a method to achieve this *** this work,the stagger and camber angle of each blade are first changed while the other geometrical parameters such as overall camber,total stagger angle,the axial overlap,percent pitch and chord ratio are ***,the overall camber angle of tandem blade is changed by increasing the difference between the stagger angle of the first and second blade while the type of two airfoils,axial overlap and percent pitch,overall chord length and overall stagger angle are *** aerodynamic performances of the generated tandem-blade cascades are obtained using two-dimensional numerical solution of *** this,a viscous turbulent flow solver is used for solving the Navier-Stokes *** these simulations,inlet Mach number is fixed to 0.6.

关键词： Tandem blade Axial compressors Cascade Camber angle Stagger angle Flow deflection loss coefficient

The Influence of Modulated Slotted Synthetic Jet on the Bypass of Hump

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Journal of Mechanics Engineering and Automation 2014年第3期4卷 225-233页

作者： Petr Pick Miroslav Andrle Vladislav Saila Milan Matej ka Department of Fluid Mechanics and Thermodynamics Faculty of Mechanical Engineering at CTU in Prague Prague 12112 CzechRepublic

This paper deals with the influence of phase modulated synthetic jet on the aerodynamics of the hump in a closed test section Of the Eiffel-type wind tunnel. Three experimental methods of measurement techniques of this phenomenon were used： the pressure profile using the Kiel total pressure probe, the velocity profile using the CTA （constant temperature anemometry） probe and the visualization of the flow field using the hot film and the thermo camera, The experimental results with and without the influence of the synthetic jet were compared, as well the impact of the phase shift of the neighbouring synthetic jets. As a reference case, the flow around the hump without the influence of the synthetic jet was selected. The results of the measurement are presented in figures and compared.

关键词： Synthetic jet Kiel probe CTA probe loss coefficient phase shift modulation.

NUMERICAL ANALYSES OF FLOW FIELDS IN A VANED DIFFUSER WITH VARIOUS FLOW RATES

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NUMERICAL ANALYSES OF FLOW FIELDS IN A VANED DIFFUSER WITH V...