Influence of a Stability Control Device on the Performance of a Cavitating Water Pump Inducer

2014 ◽  
Author(s):  
R. Lundgreen ◽  
D. Maynes ◽  
S. Gorrell ◽  
K. Oliphant
Keyword(s):  
Fluid Dynamic ◽  
Stability Control ◽  
Control Device ◽  
Design Flow ◽  
Flow Coefficient ◽  
Low Flow ◽  
Stable Operation ◽  
Dynamic Simulations ◽  
The Stability ◽  
Rotordynamic Forces

An inducer performance has been explored with and without the implementation of a stability control device. Multiphase, time-accurate computational fluid dynamic simulations have been conducted at the design flow coefficient and at two low off-design flow coefficients. At the design flow coefficient, the inducer performance was similar with and without the stability control device. At low flow coefficients, the inducer without the stability control device exhibited significant cavitation instabilities, which led to high rotordynamic forces on the inducer blades. When the stability control device was incorporated into the inducer design, nearly all of the cavitation instabilities were suppressed at low flow coefficients and the rotordynamic forces were reduced by more than an order of magnitude. Stable operation at flow coefficients far below the design value leads to a significant increase in the suction performance of the inducer, allowing pumps to operate at lower inlet pressures.

Increasing Inducer Stability and Suction Performance With a Stability Control Device

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
R. Lundgreen ◽  
D. Maynes ◽  
S. Gorrell ◽  
K. Oliphant
Keyword(s):  
Fluid Dynamic ◽  
Leading Edge ◽  
High Energy ◽  
Stability Control ◽  
Control Device ◽  
Design Flow ◽  
Flow Coefficient ◽  
Blade Tip ◽  
Rotordynamic Forces ◽  
Suction Performance

An inducer is used as the first stage of high suction performance pump. It pressurizes the fluid to delay the onset of cavitation, which can adversely affect performance in a centrifugal pump. In this paper, the performance of a water pump inducer has been explored with and without the implementation of a stability control device (SCD). This device is an inlet cover bleed system that removes high-energy fluid near the blade leading edge and reinjects it back upstream. The research was conducted by running multiphase, time-accurate computational fluid dynamic (CFD) simulations at the design flow coefficient and at low, off-design flow coefficients. The suction performance and stability for the same inducer with and without the implementation of the SCD has been explored. An improvement in stability and suction performance was observed when the SCD was implemented. Without the SCD, the inducer developed backflow at the blade tip, which led to rotating cavitation and larger rotordynamic forces. With the SCD, no significant cavitation instabilities developed, and the rotordynamic forces remained small. The lack of cavitation instabilities also allowed the inducer to operate at lower inlet pressures, increasing the suction performance of the inducer.

Reynolds Number and Roughness Effects on Turbocompressor Performance: Numerical Calculations and Measurement Data Evaluation

2020 ◽  
Author(s):  
Fabian Dietmann ◽  
Michael Casey ◽  
Damian M. Vogt
Keyword(s):  
Reynolds Number ◽  
Measurement Data ◽  
Theoretical Models ◽  
Design Flow ◽  
Flow Coefficient ◽  
Low Flow ◽  
Roughness Effects ◽  
Flow Channels ◽  
Compressor Performance ◽  
Low Flow Coefficient

Abstract Further validation of an analytic method to calculate the influence of changes in Reynolds number, machine size and roughness on the performance of axial and radial turbocompressors is presented. The correlation uses a dissipation coefficient as a basis for scaling the losses with changes in relative roughness and Reynolds number. The original correlation from Dietmann and Casey [6] is based on experimental data and theoretical models. Evaluations of five numerically calculated compressor stages at different flow coefficients are presented to support the trends of the correlation. It is shown that the sensitivity of the compressor performance to Reynolds and roughness effects is highest for low flow coefficient radial stages and steadily decreases as the design flow coefficient of the stage and the hydraulic diameter of the flow channels increases.

scholarly journals РЕЗУЛЬТАТЫ УСОВЕРШЕНСТВОВАНИЯ СТУПЕНИ ВЫСОКОНАГРУЖЕННОЙ ТУРБИНЫ НИЗКОГО ДАВЛЕНИЯ

2019 ◽  
pp. 30-37
Author(s):  
Игорь Федорович Кравченко ◽  
Сергей Александрович Хомылев
Keyword(s):  
Flow Separation ◽  
Wedge Angle ◽  
Operating Conditions ◽  
Design Flow ◽  
Flow Coefficient ◽  
Low Flow ◽  
Energy Losses ◽  
Suction Surface ◽  
Experimental Development ◽  
Leading Edges

One of the characteristic features of high loaded low-pressure turbine (LPT) with a low flow coefficient is the high-level flow deflection in the blade rows, which have sufficiently thin and strongly curved cross-section profiles. Such profiles are very sensitive to off-design flow angles, especially to positive incidence. Therefore, the effectiveness of a high loaded LPT strongly depends on the working conditions. At the same time, for various reasons, in the process of research tests or operating the engine, the operating conditions may differ greatly from the design ones. Therefore, the creation of a robust LPT design is an actual task. The article considers the computational approbation of the method of increasing the resistance to large off-design angles of attack of vane and blade rows of the intermediate stage of a high loaded LPT of an experimental engine by changing the shape of the leading edges. The turbine was previously tested as part of a full-scale engine, where it was determined that the operating conditions of the LPT and its efficiency are significantly different from the calculated ones. Numerical (CFD) analysis of the flow showed that one of the reasons for the low efficiency is the large angles of attack on the vane and blade rows of the second stage, which lead to the flow separation and an increase of the energy losses coefficients at final. The modernization of the profiles was carried out by reducing the radius and a local increase of the leading edges wedge angle without changing the basic profiles. According to the calculation results, it was allowed to significantly improve the stream. The intensity of the flow deceleration behind the shock wave at the point of transition from the circumference of the edge to the suction surface was reduced, this made it possible to eliminate or reduce the intensity of the flow separation in the vane row and significantly reduce the energy losses coefficient. A more favorable flow was also achieved in the blade row, where a slight decrease in the losses coefficient was also obtained. As a result, the efficiency of the stage and the whole LPT was increased at the off-design operating conditions. This approach can be recommended both to increase the efficiency of the turbine at the experimental development, and when designing new turbines to increase their robustness.

Continuous Spectrum of the Rotordynamic Forces on a Four Bladed Inducer

2011 ◽  
Author(s):  
Lucio Torre ◽  
Angelo Pasini ◽  
Angelo Cervone ◽  
Luca d’Agostino
Keyword(s):  
Continuous Spectrum ◽  
Experimental Technique ◽  
Cavitation Number ◽  
Flow Coefficient ◽  
Test Facility ◽  
Liquid Temperature ◽  
Qualitative And Quantitative ◽  
Experimental Campaign ◽  
The Stability ◽  
Rotordynamic Forces

The paper illustrates the results of an experimental campaign conducted in the CPRTF (Cavitating Pump Rotordynamic Test Facility) at ALTA S.p.A., aimed at characterizing the rotordynamic forces acting on a whirling four-bladed, tapered-hub, variable-pitch inducer, designated as DAPAMITO4. The roles of the imposed whirl motion of the rotor, flow coefficient, cavitation number and liquid temperature have been investigated. A novel experimental technique, consisting in measuring the continuous spectra of the forces as functions of the whirl ratio, has been developed and validated. This technique gives the possibility of extracting valuable information from the experiments by clearly identifying the qualitative and quantitative behavior of the forces, and is therefore useful to catch the unlikely foreseeable complexity of the rotordynamic forces and their consequences on the stability of axial inducers.

scholarly journals Segment-specific associations between local haemodynamic and imaging markers of early atherosclerosis at the carotid artery: an in vivo human study

2018 ◽  
Vol 15 (147) ◽  
pp. 20180352 ◽  
Author(s):  
Diego Gallo ◽  
Payam B. Bijari ◽  
Umberto Morbiducci ◽  
Ye Qiao ◽  
Yuanyuan (Joyce) Xie ◽  
...  
Keyword(s):  
Carotid Artery ◽  
Fluid Dynamic ◽  
Human Study ◽  
Low Flow ◽  
Wall Thickening ◽  
Dynamic Simulations ◽  
Vessel Wall Thickness ◽  
Imaging Markers ◽  
Early Atherosclerosis

Low and oscillatory wall shear stress (WSS) has long been hypothesized as a risk factor for atherosclerosis; however, evidence has been inferred primarily from model and post-mortem studies, or clinical studies of patients with already-developed plaques. This study aimed to identify associations between local haemodynamic and imaging markers of early atherosclerosis. Comprehensive magnetic resonance imaging allowed quantification of contrast enhancement (CE) (a marker of endothelial dysfunction) and vessel wall thickness at two distinct segments: the internal carotid artery bulb and the common carotid artery (CCA). Strict criteria were applied to a large dataset to exclude inward remodelling, resulting in 41 cases for which personalized computational fluid dynamic simulations were performed. After controlling for cardiovascular risk factors, bulb wall thickening was found to be weakly, but not significantly, associated with oscillatory WSS. CE at the bulb was significantly associated with low WSS ( p < 0.001) and low flow helicity ( p < 0.05). No significant associations were found for the CCA segment. Local haemodynamics at the bulb were significantly correlated with blood flow rates and heart rates, but not carotid bifurcation geometry (flare and curvature). Therefore low, but not oscillatory, WSS is an early independent marker of atherosclerotic changes preceding intimal thickening at the carotid bulb.

Efficiency improvement of regenerative pump using blade profile modification: Experimental study

2018 ◽  
Vol 233 (3) ◽  
pp. 448-455 ◽  
Author(s):  
J Nejad ◽  
A Riasi ◽  
A Nourbakhsh
Keyword(s):  
Experimental Study ◽  
Experimental Tests ◽  
Design Flow ◽  
Flow Coefficient ◽  
Low Flow ◽  
Impeller Blade ◽  
Profile Modification ◽  
Compact Size ◽  
Curved Blade ◽  
Regenerative Flow

Regenerative flow pump is a kind of turbomachine with the ability to generate high heads at relatively low flow rates. Despite having low hydraulic efficiency, regenerative pumps have found many applications in industries due to their simplicity, compact size, low manufacturing costs, and low specific speed. In this paper, an experimental study has been carried out to investigate the influence of impeller blade change on the performance of regenerative pump. To this end, the straight radial blades were changed to curved blades with the same inlet/outlet angles. Three forward curved blade impellers as well as straight radial blade impeller were designed and manufactured. Since the regenerative pump comply with the affinity laws, the results of experimental tests were expressed in nondimensional coefficients. The results showed that by increasing the blade angle to 10°, the efficiency increased and at higher blade angles of 30° and 50°, the efficiency decreased for all flow conditions. The best angle was obtained about 15° by curve fitting to the experimental data at the design flow coefficient.

scholarly journals The research of configuration for stability control device in smart substation

2021 ◽  
Vol 260 ◽  
pp. 02007
Author(s):  
Ye He ◽  
Binjiang Hu ◽  
Dongxu Chang ◽  
Jie Zhang ◽  
Lingfang Li ◽  
...  
Keyword(s):  
Stability Control ◽  
Control Device ◽  
Protection Device ◽  
Soft Switch ◽  
Operation And Maintenance ◽  
Technical Specifications ◽  
The Stability ◽  
Configuration Scheme ◽  
Smart Substation

A unified specification to design and operate the stability control device in smart substation has not been formed yet, which has greatly affected the promotion and application of stability control device in smart substation. Thus, referring to the technical specifications of protection device and combining to the specificity of stability control device, a full and detailed configuration scheme is proposed to meet the requirement, including the device configuration principle, the access configuration of SV and GOOSE for variable primary connection types, the virtual terminal and soft switch. This solution is beneficial to standardize the R&D of stability control device in smart substation, and to facilitate on-site debugging, operation and maintenance.

Effects of Inlet Pressure Distortion on the Performance and Flow Field of a Centrifugal Compressor at Off-Design Conditions

2012 ◽  
Author(s):  
N. Sitaram ◽  
M. Govardhan ◽  
K. V. Murali
Keyword(s):  
Flow Field ◽  
Centrifugal Compressor ◽  
Total Pressure ◽  
Static Pressure ◽  
Design Flow ◽  
Flow Coefficient ◽  
Low Flow ◽  
Performance Measurements ◽  
Perforated Sheet ◽  
Sector Angle

The present paper presents experimental results on the effects of inlet total pressure distortion on the performance and flow field of a centrifugal compressor. The total pressure at inlet is artificially distorted by means of a perforated sheet, which is supported by a support mesh. A total of eleven configurations, including clean inlet configuration, are tested. Performance measurements and impeller inlet and exit flow studies at three flow coefficients, one near design flow coefficient, one below design flow coefficient and one above design flow coefficient, are carried out. The present paper presents and discusses results at off-design flow coefficients and the effects of stage loading on the distortion effects are presented. A new parameter, Distortion Index (DI) is introduced. As DI increases, the mass averaged total pressure at exit stations decreases. Distortion sector angle of 60° having the lowest total pressure is found to be the critical sector for circumferential distortion configurations. As the Distortion Correlation parameter, DC(60) increases, the mass averaged total pressure for circumferential distortion configuration decreases, except in the case of low flow coefficient where DC(60) is nearly constant. DC(60) also increases with sector angle. The static pressure normalized with static pressure for clean inlet decreases as the distortion sector angle is increased. Distortion attenuates the static pressure as the flow passes through the vaneless diffuser. The attenuation increases with the distortion sector angle.

The Application of Safety and Stability Control Device in Middle of Henan Power Grid

2013 ◽  
Vol 860-863 ◽  
pp. 2068-2072
Author(s):  
Li Hua Zhang ◽  
Hui Lin Wang ◽  
Hong Qing Gan
Keyword(s):  
Control System ◽  
Power System ◽  
Control Strategies ◽  
Stability Control ◽  
Control Device ◽  
The Other ◽  
Stable Operation ◽  
Secondary Line ◽  
Stability Control System ◽  
Safety And Stability

Safety and stability control device is the secondary line of defense of power system stable operation. Firstly, this paper proposed the requisite of the regional safety and stability control system installed in Wuzhou 500kV switching station and the other two stations which belonged to the middle Henan power system. And then, it presented the components and elaborated control strategies of the system. It listed the situations of the united testing, at last, it summarized notes of this safety and stability control system in daily operation.

Predictability of Rotating Stall and Surge in a Centrifugal Compressor Stage With Dynamic Simulations

2014 ◽  
Author(s):  
Néstor González Díez ◽  
Jan P. M. Smeulers ◽  
Libero Tapinassi ◽  
Alberto Scotti Del Greco ◽  
Lorenzo Toni
Keyword(s):  
Centrifugal Compressor ◽  
Rotating Stall ◽  
Low Flow ◽  
Stable Region ◽  
Stable Operation ◽  
Performance Curve ◽  
Dynamic Simulations ◽  
Cycle Frequency ◽  
Flow Rates ◽  
Test Loop

A testing campaign performed on a centrifugal compressor test-loop showed that multiple areas of stable operation existed that were not expected. It was shown during the tests that after a first region of instability at low flow rates, a second stable region would appear at even lower flow rates. Dynamic simulations based on a modified Greitzer’s model have been performed in order to assess the predictability of these unsteady phenomena. The study is focused on matching the dynamic simulations and the experimental results, concerning the different stable and unstable regions. It was of particular interest to verify the simulation results for the first region of instability, where rotating stall is suspected to occur. In this region the time-averaged performance curve showed a positive, i.e. unstable, slope. The performance curve presents then two regions with negative, stable, slope. The model shows good agreement with the measured pressure fluctuations when operated in surge conditions, both in terms of fundamental surge cycle frequency and pulsation amplitude. Capturing the pressure variations for the rotating stall range proved more difficult and subject to the implemented performance curve, which is considered uncertain in this range. By tuning the performance curve in the corresponding range of flow rates, a satisfactory match with the test results could be achieved. The second range of stability was correctly captured by also modifying the compressor performance curve.

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