According to the influence of the combination of short-distance coal seam group on mining roadway, using numerical simulation software FLAG2D to draw the abutment pressure distribution ahead the working face and the a...According to the influence of the combination of short-distance coal seam group on mining roadway, using numerical simulation software FLAG2D to draw the abutment pressure distribution ahead the working face and the area of influence in fully-mechanized mining conditions, the variation rules of surrounding rock supporting pressure of floor roadway and the deformation rules were summarized. GYS-300 anchor dynamometer was used to measure the roadway surface displacement, and the conclusions of numerical simulation were verified.展开更多
Aiming at the problem that the total pressure loss of the flue of the electric precipitator of the 350 MW unit of a power plant to the inlet of the draft fan is too large,the numerical simulation software Fluent and t...Aiming at the problem that the total pressure loss of the flue of the electric precipitator of the 350 MW unit of a power plant to the inlet of the draft fan is too large,the numerical simulation software Fluent and the standard k-εmodel was used to simulate the flue,the results show that the main part of the flue mean total pressure loss is derived from the confluence header and elbow.In order to reduce the loss and consider the cost of transformation,the concept of twodimensional feature surface is established,gradually proposed three sets of flue transformation program and analysis of the flue transformation program drag reduction effect,the results show that the total reduction of the flue can be reduced from 486 Pa to 89 Pa and the reduction rate is 81.7%,which is the best solution;The concept of two-dimensional feature plane is helpful for quick condensing of flue;Double V-type structure of the convergence of the box has a better drag reduction effect.展开更多
Inlet total pressure distortion has great adverse effects on the aero-engine performance. The distorted flow passes through the compressor and becomes non-uniform in the downstream blade rows. Different from previous ...Inlet total pressure distortion has great adverse effects on the aero-engine performance. The distorted flow passes through the compressor and becomes non-uniform in the downstream blade rows. Different from previous studies based on the assumption of circumferential uniformity, this study aims to improve circumferential non-uniform flow with the non-axisymmetric structure. Non-axisymmetric stator clearance was adopted to resolve the effects of non-uniform flow caused by inlet total pressure distortion in this paper. The 9 stators with tip clearance were installed in the distorted region and the flow field structure and performance under different operating conditions was studied. The study finds that the non-axisymmetric compressor with 9 tip clearance stators can ensure compressor efficiency while improving compressor stability margin. What’s more, the separation range and strength in the distorted region can be reduced significantly and the anti-distortion capability of compressor can be enhanced.展开更多
Significant aerodynamic engine instability can occur during the operation of marine gas turbines as airflow enters the compressor through a 90°turning and causes inlet distortion.This study adopts the method of s...Significant aerodynamic engine instability can occur during the operation of marine gas turbines as airflow enters the compressor through a 90°turning and causes inlet distortion.This study adopts the method of simulating board equivalence to provide the target distortion flow field for ship compressors.The characteristics of the flow field behind the simulated board are obtained through experiments and numerical simulations,through which the relationship between the height of the simulated board and the total pressure distortion is elucidated.Subsequently,the study summarizes the prediction formula to achieve a distortion prediction of 0.8%–7.8%.In addition,this work analyzes the effects of drilling methods and diameters on flow nonuniformity by drilling holes into the simulation board.The results indicate that drilling holes on the board can weaken the nonuniformity of the flow field within a certain range and change the distribution pattern of total pressure in the cross-section.Furthermore,the total pressure distortion no longer changes significantly when the number of holes is too large.The proposed double simulation board structure is capable of obtaining the following two types of distorted flow fields:symmetrical dual lowpressure zones and low-pressure zones with high distortion intensity at the compressor inlet.The distortion equivalent simulation method proposed in this work can obtain various types of distortion spectra,thereby meeting the distortion parameter requirements for the antidistortion testing of marine engines.展开更多
为了考察不同抽吸状态下卷烟动态通风特征,测量了3R4F卷烟在非燃烧不同抽吸状态下的压降与总通风率,建立了包含通风孔结构的全烟支气体流动3维数学模型,通过测量3R4F卷烟在17.5 m L/s恒速抽吸过程中的压降与总通风率对数学模型进行了验...为了考察不同抽吸状态下卷烟动态通风特征,测量了3R4F卷烟在非燃烧不同抽吸状态下的压降与总通风率,建立了包含通风孔结构的全烟支气体流动3维数学模型,通过测量3R4F卷烟在17.5 m L/s恒速抽吸过程中的压降与总通风率对数学模型进行了验证,发现测量值和模拟值两者相对误差均小于1.5%。利用所建数学模型分析了17.5 m L/s恒速抽吸状态下与ISO标准抽吸状态下3R4F卷烟内部气流压降和速率的3维分布规律以及轴向分布规律。结果显示:在恒速抽吸状态下,从3R4F卷烟纸进入卷烟内部的气流速率与距卷烟气流入口端距离成正比例关系;在ISO标准抽吸状态下,3R4F卷烟压降与抽吸流量呈正比例关系,而卷烟总通风率与抽吸流量无关并保持恒定不变。所得结果可为深入理解卷烟燃烧过程中气流运动规律、燃烧过程调控机理以及卷烟参数优化设计提供理论支持。展开更多
文摘According to the influence of the combination of short-distance coal seam group on mining roadway, using numerical simulation software FLAG2D to draw the abutment pressure distribution ahead the working face and the area of influence in fully-mechanized mining conditions, the variation rules of surrounding rock supporting pressure of floor roadway and the deformation rules were summarized. GYS-300 anchor dynamometer was used to measure the roadway surface displacement, and the conclusions of numerical simulation were verified.
文摘Aiming at the problem that the total pressure loss of the flue of the electric precipitator of the 350 MW unit of a power plant to the inlet of the draft fan is too large,the numerical simulation software Fluent and the standard k-εmodel was used to simulate the flue,the results show that the main part of the flue mean total pressure loss is derived from the confluence header and elbow.In order to reduce the loss and consider the cost of transformation,the concept of twodimensional feature surface is established,gradually proposed three sets of flue transformation program and analysis of the flue transformation program drag reduction effect,the results show that the total reduction of the flue can be reduced from 486 Pa to 89 Pa and the reduction rate is 81.7%,which is the best solution;The concept of two-dimensional feature plane is helpful for quick condensing of flue;Double V-type structure of the convergence of the box has a better drag reduction effect.
基金supported by the National Natural Science Foundation of China(No.51576024,51436002)the Double First Class Construction Special Innovation Project of Dalian Maritime University(No.BSCXXM008)。
文摘Inlet total pressure distortion has great adverse effects on the aero-engine performance. The distorted flow passes through the compressor and becomes non-uniform in the downstream blade rows. Different from previous studies based on the assumption of circumferential uniformity, this study aims to improve circumferential non-uniform flow with the non-axisymmetric structure. Non-axisymmetric stator clearance was adopted to resolve the effects of non-uniform flow caused by inlet total pressure distortion in this paper. The 9 stators with tip clearance were installed in the distorted region and the flow field structure and performance under different operating conditions was studied. The study finds that the non-axisymmetric compressor with 9 tip clearance stators can ensure compressor efficiency while improving compressor stability margin. What’s more, the separation range and strength in the distorted region can be reduced significantly and the anti-distortion capability of compressor can be enhanced.
基金Supported by the National Natural Science Foundation of China(No.52101348)the National Science and Technology Major Project(Y2019-VIII-0013-0174)the Fundamental Research Funds for the Central Universities(No.3072022JC0301)。
文摘Significant aerodynamic engine instability can occur during the operation of marine gas turbines as airflow enters the compressor through a 90°turning and causes inlet distortion.This study adopts the method of simulating board equivalence to provide the target distortion flow field for ship compressors.The characteristics of the flow field behind the simulated board are obtained through experiments and numerical simulations,through which the relationship between the height of the simulated board and the total pressure distortion is elucidated.Subsequently,the study summarizes the prediction formula to achieve a distortion prediction of 0.8%–7.8%.In addition,this work analyzes the effects of drilling methods and diameters on flow nonuniformity by drilling holes into the simulation board.The results indicate that drilling holes on the board can weaken the nonuniformity of the flow field within a certain range and change the distribution pattern of total pressure in the cross-section.Furthermore,the total pressure distortion no longer changes significantly when the number of holes is too large.The proposed double simulation board structure is capable of obtaining the following two types of distorted flow fields:symmetrical dual lowpressure zones and low-pressure zones with high distortion intensity at the compressor inlet.The distortion equivalent simulation method proposed in this work can obtain various types of distortion spectra,thereby meeting the distortion parameter requirements for the antidistortion testing of marine engines.
文摘为了考察不同抽吸状态下卷烟动态通风特征,测量了3R4F卷烟在非燃烧不同抽吸状态下的压降与总通风率,建立了包含通风孔结构的全烟支气体流动3维数学模型,通过测量3R4F卷烟在17.5 m L/s恒速抽吸过程中的压降与总通风率对数学模型进行了验证,发现测量值和模拟值两者相对误差均小于1.5%。利用所建数学模型分析了17.5 m L/s恒速抽吸状态下与ISO标准抽吸状态下3R4F卷烟内部气流压降和速率的3维分布规律以及轴向分布规律。结果显示:在恒速抽吸状态下,从3R4F卷烟纸进入卷烟内部的气流速率与距卷烟气流入口端距离成正比例关系;在ISO标准抽吸状态下,3R4F卷烟压降与抽吸流量呈正比例关系,而卷烟总通风率与抽吸流量无关并保持恒定不变。所得结果可为深入理解卷烟燃烧过程中气流运动规律、燃烧过程调控机理以及卷烟参数优化设计提供理论支持。
