This paper focuses on the response of a high aspect ratio,low speed contra-rotating fan with complex inflow distortion.The total pressure at the inlet is artificially distorted by means of two different sets of screen...This paper focuses on the response of a high aspect ratio,low speed contra-rotating fan with complex inflow distortion.The total pressure at the inlet is artificially distorted by means of two different sets of screens with different porosities to generate a hub-strong complex distortion and a tip-strong complex distortion.Detailed flow analyses were conducted for the design speed of rotor-1 in combination with off design speeds of rotor-2 both for the design and the peak pressure mass flow rates.In order to understand the extent of inlet distortion,the distortion sector was rotated circumferentially at intervals of 151 to cover the entire annulus.Detailed measurements of total pressure,static pressure,velocity components and flow angles were carried out at the inlet of the first rotor,between the two rotors and at the exit of the second rotor using three seven hole probes.The study reveals a few interesting aspects on the effect of complex inflow distortion on the flow behavior of a contra-rotating stage.The presence of a low porosity screen reduces the magnitude of axial velocity and generates higher spread of distortion near the localized region of placement of the screen.The hub-strong complex distortion has a greater effect of presence of this low porosity screen in both circumferential and radial directions.This leads to higher stagnation pressure variation at the inlet.On the other hand,for the tip-strong complex distortion case,the extent of distortion is observed to be higher in the circumferential direction towards the casing rather than radial.The localized improvement in the flow(in tip-strong inflow distortion)near the tip region improves the performance both in terms of pressure rise and efficiency of stage compared to hub–strong complex distortion.展开更多
Boundary layer ingesting(BLI)fans are required to operate under distorted inflow conditions,which significantly reduces their efficiency[1,2].Accurately predicting fan losses is crucial for designing high-performance,...Boundary layer ingesting(BLI)fans are required to operate under distorted inflow conditions,which significantly reduces their efficiency[1,2].Accurately predicting fan losses is crucial for designing high-performance,distortion-tolerant fans.展开更多
With increasing emphasis on renewable sources of energy,the gas turbine engine faces several challenges in evolving its design,to remain relevant.Compressor is one of the main components,which accounts for one-third o...With increasing emphasis on renewable sources of energy,the gas turbine engine faces several challenges in evolving its design,to remain relevant.Compressor is one of the main components,which accounts for one-third of the engine length.Compressor designers have been exploring different ideas to achieve maximum pressure rise with minimum number of stages required.Tandem blading is one such novel design that has demonstrated higher diffusion capability than a single rotor blade.A single blade,with a higher diffusion factor,carries the risk of flow separation against the adverse pressure gradient of the compressor flow.In the tandem blading concept,a single blade is split into forward and aft blade.The gap that is created between the forward and aft blade,serves as a mechanism to energize the sluggish flow over the aft blade suction surface,which in turn helps in mitigating the flow separation.The present experimental work is aimed at exploring the feasibility of a tandem rotor in an axial flow compressor under the clean and radially distorted inflows.Steady and unsteady experimental results of the tandem rotor are included in this paper.The stage performance characteristics,variation of total pressure,flow coefficient,and exit flow angle along the blade span for clean and distorted flow is included in this paper.Some results of a steady Reynolds-averaged Navier-Stokes simulation are also included to give some insight into the complex flow field of the tandem rotor.Wavelet transform,fast Fourier transform analysis,and visual inspection of casing pressure traces are used to analyze the unsteady result of the tandem rotor in clean and distorted flow.The tandem rotor is able to achieve its design pressure ratio and has a stall margin of 9%under the clean flow condition.Initially,stall appears as a low-intensity spike for all the cases,which turns into a long length-scale disturbance within three rotor revolutions.A modal wave of low frequency is also observed under clean and distorted inflows.展开更多
基金This work was partially funded by the Aeronautics Research and Development Board of India and is gratefully acknowledged.
文摘This paper focuses on the response of a high aspect ratio,low speed contra-rotating fan with complex inflow distortion.The total pressure at the inlet is artificially distorted by means of two different sets of screens with different porosities to generate a hub-strong complex distortion and a tip-strong complex distortion.Detailed flow analyses were conducted for the design speed of rotor-1 in combination with off design speeds of rotor-2 both for the design and the peak pressure mass flow rates.In order to understand the extent of inlet distortion,the distortion sector was rotated circumferentially at intervals of 151 to cover the entire annulus.Detailed measurements of total pressure,static pressure,velocity components and flow angles were carried out at the inlet of the first rotor,between the two rotors and at the exit of the second rotor using three seven hole probes.The study reveals a few interesting aspects on the effect of complex inflow distortion on the flow behavior of a contra-rotating stage.The presence of a low porosity screen reduces the magnitude of axial velocity and generates higher spread of distortion near the localized region of placement of the screen.The hub-strong complex distortion has a greater effect of presence of this low porosity screen in both circumferential and radial directions.This leads to higher stagnation pressure variation at the inlet.On the other hand,for the tip-strong complex distortion case,the extent of distortion is observed to be higher in the circumferential direction towards the casing rather than radial.The localized improvement in the flow(in tip-strong inflow distortion)near the tip region improves the performance both in terms of pressure rise and efficiency of stage compared to hub–strong complex distortion.
基金supported by the National Key Research and Development Program(Grant No.2022YFF0708903)the Ningbo Key Technology Re-search and Development Program(Grant No.2023Z018)+3 种基金the National Natural Science Foundation of China(Grant No.52275043)the Youth Fund of National Natural Science Foundation of China(Grant Nos.72301015,52105046)the Young Elite Scientist Sponsorship Program by China Association for Science and Technology(Grant Nos.2022QNRC001,YESS20220292)the Liupanshan Laboratory Basic Research Program(Grant No.LPS-2024-KY-D-JC-0009)。
文摘Boundary layer ingesting(BLI)fans are required to operate under distorted inflow conditions,which significantly reduces their efficiency[1,2].Accurately predicting fan losses is crucial for designing high-performance,distortion-tolerant fans.
文摘With increasing emphasis on renewable sources of energy,the gas turbine engine faces several challenges in evolving its design,to remain relevant.Compressor is one of the main components,which accounts for one-third of the engine length.Compressor designers have been exploring different ideas to achieve maximum pressure rise with minimum number of stages required.Tandem blading is one such novel design that has demonstrated higher diffusion capability than a single rotor blade.A single blade,with a higher diffusion factor,carries the risk of flow separation against the adverse pressure gradient of the compressor flow.In the tandem blading concept,a single blade is split into forward and aft blade.The gap that is created between the forward and aft blade,serves as a mechanism to energize the sluggish flow over the aft blade suction surface,which in turn helps in mitigating the flow separation.The present experimental work is aimed at exploring the feasibility of a tandem rotor in an axial flow compressor under the clean and radially distorted inflows.Steady and unsteady experimental results of the tandem rotor are included in this paper.The stage performance characteristics,variation of total pressure,flow coefficient,and exit flow angle along the blade span for clean and distorted flow is included in this paper.Some results of a steady Reynolds-averaged Navier-Stokes simulation are also included to give some insight into the complex flow field of the tandem rotor.Wavelet transform,fast Fourier transform analysis,and visual inspection of casing pressure traces are used to analyze the unsteady result of the tandem rotor in clean and distorted flow.The tandem rotor is able to achieve its design pressure ratio and has a stall margin of 9%under the clean flow condition.Initially,stall appears as a low-intensity spike for all the cases,which turns into a long length-scale disturbance within three rotor revolutions.A modal wave of low frequency is also observed under clean and distorted inflows.
