Parametric Investigation of Circumferential Grooves on Compressor Rotor Performance

2010 ◽  
Vol 132 (12) ◽  
Author(s):  
Yanhui Wu ◽  
Wuli Chu ◽  
Haoguang Zhang ◽  
Qingpeng Li
Keyword(s):  
Numerical Investigation ◽  
High Speed ◽  
Orthogonal Experiment ◽  
Experimental Investigations ◽  
Small Scale ◽  
Stall Margin ◽  
Compressor Rotor ◽  
Set Up ◽  
Compound Effect ◽  
Unloading Effect

This paper presents numerical and experimental investigations about grooved casing treatment with the help of a high-speed small-scale compressor rotor. First, the numerical investigation seeks to offer a contribution of understanding the working mechanism by which circumferential grooves improve stall margin. It is found that stall margin gain due to the presence of circumferential grooves arises from the suction-injection effect and the near-tip unloading effect. Based on that, the philosophy of design of experiment is then set up. Finally, parametric studies are carried out through systematical experiments. It is found that the orthogonal experiment and the factorial analyses are successful in identifying the “best casing configuration” in terms of stall margin improvement. However, the ineffectiveness of the deduction from simulations suggests that the secondary flow circulations on stall margin gain should not be neglected, and the overall contribution of each groove to stall margin gain depends on its unloading effect and the compound effect of suction-injection. Further numerical investigation will focus on how to set up quantitative criteria to evaluate the compound effect of suction-injection and the unloading effect on stall margin gain respectively in each groove.

Design and Experimental Study of a Vespiary Exsector

2012 ◽  
Vol 468-471 ◽  
pp. 397-400
Author(s):  
Yan Hai Tang ◽  
Jin Bing Hu ◽  
Ling Yang ◽  
Pei Xiang He
Keyword(s):  
High Speed ◽  
Orthogonal Experiment ◽  
Cutting Speed ◽  
Cutting Parameters ◽  
Small Scale ◽  
Feed Speed ◽  
Revolution Speed ◽  
Significance Levels ◽  
Sealing Mechanism ◽  
Low Efficiency

The traditional removal method of a vespiary is labor-costing with characteristics of low efficiency and safety. According to the work high above the ground with hidden risk of the vespiary removal, a mechanical vespiary exsector was designed. The exsector is driven by a high speed motor, and the vespiary is removed by a cutting wire with high revolution speed. The cutting part can rotate 90 through drawing a pulling rope. A 2-layer sealing mechanism is operated through another pulling rope. The vespiary exsector has overall characteristics of small scale, light weight and good dexterity. Orthogonal experiment results show that factors of cutting speed and feed speed significantly contribute the width of cutting slot at the significance levels of 0.01 and 0.05 respectively, and the optimum cutting parameters are: cutting speed 10000rpm, feed speed 0.04m/s and diameter of the cutting wire 2mm.

Application of an Arbitrary Lagrangian Eulerian Method to Describe High Velocity Gas-Particle Flow Behavior

2011 ◽  
Author(s):  
D. M. Fox ◽  
J. S. Lee
Keyword(s):  
High Velocity ◽  
High Speed ◽  
Flow Behavior ◽  
Constitutive Models ◽  
Experimental Investigations ◽  
Small Scale ◽  
Arbitrary Lagrangian Eulerian ◽  
High Velocity Flow ◽  
Solid Objects ◽  
Velocity Flow

Novel computational and small-scale experimental investigations were performed in order to better understand the high velocity flow behavior of gas-particle mixtures. The motion of solid objects impacted by the flow of the mixtures was measured by use of high-speed digital video photography. Computations were performed by use of an arbitrary Lagrangian Eulerian (ALE) treatment in a nonlinear finite element code. Constitutive models for description of the solid component of the gas-particle blend were developed based on quasi-statically determined test results. It was observed that there was very close agreement between experimental and computational results and that it was possible to accurately predict the high velocity flow behavior of the gas-particle mixture using quasi-statically determined constitutive models.

scholarly journals Numerical and Experimental Investigations of Composite Solar Walls Integrating Sensible or Latent Heat Thermal Storage

2020 ◽  
Vol 10 (5) ◽  
pp. 1854 ◽  
Author(s):  
Enghok Leang ◽  
Pierre Tittelein ◽  
Laurent Zalewski ◽  
Stéphane Lassue
Keyword(s):  
Weather Conditions ◽  
Energy Performance ◽  
Cold Season ◽  
Experimental Investigations ◽  
Small Scale ◽  
Storage Element ◽  
Storage Wall ◽  
And Performance ◽  
Set Up ◽  
Solar Wall

This article studies a composite solar wall with latent storage (TES) designed to heat rooms inside buildings during the cold season. No numerical model of the composite solar wall is currently available in the Dymola/Modelica software library. The first objective of this work is to develop one such model. The article describes the elementary components, along with the equations that allow modeling the heat transfers and storage phenomena governing both the thermal behavior and performance of the solar wall. This model was built by assembling various existing basic elements from the software’s “Building” library (e.g., models of heat transfer by convection, radiation and conduction) and then creating new elements, such as the storage element incorporating the phase change material (PCM). To validate this solar wall model, numerical results are compared to experimental data stemming from a small-scale composite solar wall manufactured in our laboratory, and the experimental set-up could be tested under real weather conditions. After verifying the level of confidence in the model, the energy performance of two solar walls, one with a conventional storage wall (sensible heat storage) the other containing a PCM (the same as in the experiment), are compared. The result indicates that the solar wall incorporating a PCM does not in this case release any more energy in the room to be heated.

On the effect of surface roughness on velocity profiles and runout lengths of dry granular flows

2020 ◽  
Author(s):  
Lukas Reider ◽  
Roland Kaitna
Keyword(s):  
Surface Roughness ◽  
Cross Sections ◽  
High Speed ◽  
Maximum Flow ◽  
Velocity Profiles ◽  
Small Scale ◽  
Relative Roughness ◽  
Laser Sensors ◽  
Mass Flows ◽  
Set Up

<p>Gravitational mass flows like debris flows are often physically modelled as an assembly of particles flowing in simplified flume configurations. There is indication that natural flows exhibit a combined movement of sliding and internal deformation, which is not well understood and underrepresented in scaled laboratory experiments. In this study we investigate the effect of the surface roughness on the velocity profile and the runout of small-scale, dry granular avalanches. The experimental set-up is a 0.17 m wide flume with an inclination of 34° for the first 1.5 m, following an 0.8 m curved transition zone with a radius of 1.7 m, and ending in a runout zone with an angle of 4°. The tested material consisted of non-perfect spherical ceramic beads with a diameter of 2.8 to 4.3 mm. We tested four different types of surface roughness ranging from 0 to 6 mm height and additionally one macro roughness, which was higher than the maximum flow height. To also get information about the influence of the relative roughness experiments with three different starting volumes were undertaken. All fourteen experimental variations were repeated three times. Flow heights were measured with laser sensors at four different positions along the channel. Three of them were used to calculate the mean front velocity of the flowing mass in two cross sections. Furthermore, the experiments were recorded with a high-speed camera through one sidewall out of acrylic glass. The recordings were analysed using a PIV (Particle Image Velocimetry) software to derive velocity profiles in 1/1500 second time steps. Results show that the velocity profiles changed from the head to the tail of the flow and that the profiles of the two roughest surfaces are more alike than the smooth roughness configurations. The fraction of sliding on the total movement varied between 0 and close to unity. The runout length decreased the higher the roughness was and increased with higher starting volume. The shape of the velocity profiles at the deepest sections of the flows changed with surface roughness and with starting volumes. Only the velocity profiles for the two roughest surfaces show an inflection point. Our experiments highlight the importance of surface roughness as well as relative roughness for granular mass flows and provide data for model testing.</p>

Numerical Investigation of Different Casing Treatments on Performance of a High Speed Centrifugal Compressor Stage

2011 ◽  
Author(s):  
Yan Ma ◽  
Guang Xi ◽  
Guangkuan Wu
Keyword(s):  
Numerical Investigation ◽  
Centrifugal Compressor ◽  
High Speed ◽  
The Other ◽  
Compressor Stage ◽  
Stall Margin ◽  
Casing Treatment ◽  
Centrifugal Compressor Stage ◽  
And Performance ◽  
Casing Treatments

In this paper, two different casing treatment devices—one adopting inlet recirculation at the shroud side of the impeller inlet and the other adopting circumferential casing grooves at the shroud side of the vaneless space, are designed for a high speed centrifugal compressor stage. The effects of different casing treatments to the flow range and performance of the centrifugal compressor stage are studied numerically. The results indicate that traditional inlet recirculation at impeller inlet does not extend the stall margin of the stage and the performance deteriorates due to the adding of the extra device. The study also shows that, when the location of the bleed slot moves downstream, the performance of the stage deteriorates due to the longer flow path. Moreover, the 2mm depth circumferential casing grooves extend the stall margin by about 12.05%. By contrast, the 6mm depth and 10mm depth grooves extend the stall margin by 3% and 2.4% respectively.

scholarly journals SDN-Based WAN Optimization: PCE Implementation in Multi-Domain MPLS Networks Supported By BGP-LS

2017 ◽  
Vol 22 (1) ◽  
pp. 35-48 ◽  
Author(s):  
Grzegorz Rzym ◽  
Krzysztof Wajda ◽  
Piotr Chołda
Keyword(s):  
Traffic Engineering ◽  
High Speed ◽  
Experimental Investigations ◽  
Optimization Approach ◽  
Path Delay ◽  
Path Computation ◽  
Flexible Resource ◽  
Virtual Routers ◽  
Set Up ◽  
Sdn Controller

Abstract In order to provide efficient and flexible resource management and path set-up in high-speed MPLS/GMPLS networks, the PCE (Path Computation Element) architecture was proposed by IETF. Implementation of a central module for the path set-up enables network operators to run path establishment operations for applications with explicitly defined objective functions and QoS requirements. The paper reports on recent research and experimental investigations with PCE-based path computation performed according to the 3- layered traffic engineering (TE) system consisting of: (1) a PCE module equipped with the IBM Cplex LP solver used in the highest layer 3, and (2) a SDN controller in the intermediate layer 2 responsible for transferring path setup requests towards virtual routers in the lowest layer 1. The presented results show usefulness of the PCE-supporting architecture with an SDN controller and applicability of bandwidth-oriented optimization based on real-time focused constraints (path delay limits). We emphasise that even a simple optimization approach shows the power provided by the SDN, i.e., flexibility of flows. This property is in practice not feasible in classical IP or MPLS networks, that is the usage of flow-based routing provided by network programmability really opens opportunities in network tuning

3D Numerical Investigation of Tandem Airfoils for a Core Compressor Rotor

2008 ◽  
Author(s):  
Jonathan McGlumphy ◽  
Wing-Fai Ng ◽  
Steven R. Wellborn ◽  
Severin Kempf
Keyword(s):  
Turbulent Flow ◽  
Fluid Mechanics ◽  
Numerical Investigation ◽  
Boundary Layers ◽  
Three Dimensional ◽  
Compressor Blade ◽  
Stall Margin ◽  
Compressor Rotor ◽  
Blade Geometry

The tandem airfoil has potential to do more work as a compressor blade than a single airfoil without incurring higher losses. The goal of this work is to evaluate the fluid mechanics of a tandem rotor in the rear stages of a core compressor. As such, the results are constrained to shock-free, fully turbulent flow with thick endwall boundary layers at the inlet. A high hub-to-tip ratio 3D blade geometry was developed based upon the best-case tandem airfoil configuration from a previous 2D study. The 3D tandem rotor was simulated in isolation in order to scrutinize the fluid mechanisms of the rotor, which had not previously been well documented. A geometrically similar single blade rotor was also simulated under the same conditions for a baseline comparison. The tandem rotor was found to outperform its single blade counterpart by attaining a higher work coefficient, polytropic efficiency and numerical stall margin. An examination of the tandem rotor fluid mechanics revealed that the forward blade acts in a similar manner to a conventional rotor. The aft blade is strongly dependent upon the flow it receives from the forward blade, and tends to be more three-dimensional and non-uniform than the forward blade.

Performance Desensitization for a High-Speed Axial Compressor

2018 ◽  
Author(s):  
Yassine Souleimani ◽  
Huu Duc Vo ◽  
Hong Yu
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Tip Clearance ◽  
Lower Sensitivity ◽  
Tip Leakage Flow ◽  
Stall Margin ◽  
Casing Treatment ◽  
Compressor Rotor

The increase in compressor tip clearance over the lifespan of an aero-engine leads to a long-term degradation in its fuel consumption and operating envelope. A highly promising recent numerical study on a theoretical high-speed axial compressor rotor proposed a novel casing treatment to decrease performance and stall margin sensitivity to tip clearance increase. This paper aims to apply and analyze, through CFD simulations, this casing treatment concept to a representative production axial compressor rotor with inherently lower sensitivity to tip clearance increase and complement the explanation on the mechanism behind the reduction in sensitivity. Simulations of the baseline rotor showed that the lower span region contribute as much to the pressure ratio sensitivity as the tip region which is dominated by tip leakage flow. In contrast, the efficiency sensitivity is mainly driven by losses occurring in the tip region. The novel casing treatment was successfully applied to the baseline rotor through a design refinement. Although the casing treatment causes some penalty in nominal performance, it completely reversed the pressure ratio sensitivity (i.e. pressure ratio increases with tip clearance) and reduced the efficiency sensitivity. The reversed pressure ratio sensitivity is explained by a rotation in the core flow in the lower span region indirectly induced by the flow injection from the casing treatment. The lower efficiency sensitivity comes from a reduction in the amount of fluid that crosses the tip clearance of two adjacent blades, known as double leakage. The casing treatment’s beneficial effect on stall margin sensitivity is less obvious because of the stall inception type of the baseline rotor and its change in the presence of the casing treatment.

The Effect of Steam Ingestion on Transonic Rotor Stall Margin

2007 ◽  
Author(s):  
A. J. Gannon ◽  
G. V. Hobson ◽  
T. A. Payne ◽  
S. E. Zarro
Keyword(s):  
High Speed ◽  
Initial Conditions ◽  
Flow Conditions ◽  
Stall Margin ◽  
Transonic Compressor ◽  
Compressor Rotor ◽  
High Speed Data ◽  
Inlet Conditions ◽  
Transonic Rotor ◽  
Temperature Water

The adverse effect of high temperature water vapor on the stall margin of a transonic compressor rotor is investigated. This type of flow condition is experienced during the takeoff of carrier born aircraft. An experiment is designed to replicate these flow conditions on a transonic compressor test rig. The transient inlet conditions are measured and the changes in gas properties as well as the reduction in stall margin for differing steam inlet pressures are presented. High speed data measurements are used to investigate the initial conditions of the compressor before steam is introduced to the flow. Evidence of pre-cursors rotating at near half rotor speed are found and the strength of these appear to give an indication of the compressor’s susceptibility to stall.

Performance enhancement in transonic axial compressors using blade tip injection coupled with casing treatment

2005 ◽  
Vol 219 (5) ◽  
pp. 321-331 ◽  
Author(s):  
B. H. Beheshti ◽  
B Farhanieh ◽  
K Ghorbanian ◽  
J. A. Teixeira ◽  
P. C. Ivey
Keyword(s):  
Flow Injection ◽  
High Speed ◽  
Performance Enhancement ◽  
Three Dimensional ◽  
Stall Margin ◽  
Casing Treatment ◽  
Transonic Compressor ◽  
Compressor Rotor ◽  
Blade Tip ◽  
Tip Injection

The casing treatment and flow injection upstream of the rotor tip are two effective approaches in suppressing instabilities or recovering from a fully developed stall. This paper presents numerical simulations for a high-speed transonic compressor rotor, NASA Rotor 37, applying a state-of-the-art design for the blade tip injection. This is characterized by introducing a jet flow directly into the casing treatment machined into the shroud. The casing treatment is positioned over the blade tip region and exceeds the impeller axially by ∼30 per cent of the tip chord both in the upstream and in the downstream directions. To numerically solve the governing equations, the three-dimensional finite element based finite volume method CFD solver CFX-TASCflow (version 2.12.1) is employed. For a compressible flow with varying density, Reynolds-averaging leads to appearance of complicated correlations. To avoid this, the mass-weighted or Favre-averaging is applied. Using an injected mass flow of 2.4 per cent of the annulus flow, the present design can improve stall margin by up to 7 per cent when compared with a smooth casing compressor without tip injection. This research can lead to an optimum design of recirculating casing treatments or other mechanisms for performance enhancement applying tip flow injection.

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