scholarly journals Analysis of Pressure Pulsation Induced by Rotor-Stator Interaction in Nuclear Reactor Coolant Pump

2017 ◽  
Vol 2017 ◽  
pp. 1-18 ◽  
Author(s):  
Xu Zhang ◽  
Pengfei Wang ◽  
Xiaodong Ruan ◽  
Zhongbin Xu ◽  
Xin Fu
Keyword(s):  
Flow Rate ◽  
Pressure Pulsation ◽  
Operating Conditions ◽  
Impeller Blade ◽  
Coolant Pump ◽  
Guide Vanes ◽  
Rate Distribution ◽  
Reactor Coolant ◽  
Rotor Stator Interaction ◽  
Phase Differences

The internal flow of reactor coolant pump (RCP) is much more complex than the flow of a general mixed-flow pump due to high temperature, high pressure, and large flow rate. The pressure pulsation that is induced by rotor-stator interaction (RSI) has significant effects on the performance of pump; therefore, it is necessary to figure out the distribution and propagation characteristics of pressure pulsation in the pump. The study uses CFD method to calculate the behavior of the flow. Results show that the amplitudes of pressure pulsation get the maximum between the rotor and stator, and the dissipation rate of pressure pulsation in impellers passage is larger than that in guide vanes passage. The behavior is associated with the frequency of pressure wave in different regions. The flow rate distribution is influenced by the operating conditions. The study finds that, at nominal flow, the flow rate distribution in guide vanes is relatively uniform and the pressure pulsation amplitude is the smallest. Besides, the vortex shedding or backflow from the impeller blade exit has the same frequency as pressure pulsation but there are phase differences, and it has been confirmed that the absolute value of phase differences reflects the vorticity intensity.

Investigation on Rotor-Stator Interaction in a Low Specific Speed Centrifugal Pump

2015 ◽  
Author(s):  
Ning Zhang ◽  
Minguan Yang ◽  
Bo Gao ◽  
Zhong Li ◽  
Dan Ni
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Pulsation ◽  
Vortical Structure ◽  
Fluid Dynamic ◽  
High Amplitude ◽  
Operating Conditions ◽  
Rotor Stator Interaction ◽  
Low Specific Speed ◽  
Specific Speed

In centrifugal pump, due to intense rotor-stator interaction, high amplitude pressure pulsating would be induced, and it has a crucial influence on the stable operating of the pump. In this paper, a low specific speed centrifugal pump is investigated to illustrate unsteady flow within the centrifugal pump. Pressure pulsation signals are attained by mounting 20 monitoring points along the spiral volute, covering all the interested region of the model pump. FFT (Fast Fourier Transform algorithm) is applied to analyze the time-domain pressure signals. Results show that in pressure spectra, evident peaks at blade passing frequency fBPF together with its high harmonics can be identified, and the amplitudes are closely associated with operating conditions of the model pump and the positions of the monitoring points. At nominal flow rate, four vortical regions with high amplitude are captured inside the model pump. And the unsteady vortical structure at the near tongue region is related to the relative position of the impeller with respect to the tongue, and the upstream effect of the volute tongue significantly affects the vorticity distribution on the blade pressure side. At off-design conditions, the interaction pattern between the vortical structure and the volute tongue is significantly affected compared with that at the rated condition, as to the upstream effect of the tongue. At high flow rate, partial vortex would separate from the main vortex, but at low flow rate, the cutting and impingement effects of the tongue are much weaker due to almost all the vortex moving to the narrow side of the tongue. Based on the analysis of rotor-stator interaction in the model pump, some conclusions could be obtained. Pressure amplitudes at fBPF are associated with the positions of monitoring points and operating conditions of the model pump. Vorticity magnitude at blade exit increases as the impeller passes the volute tongue. And the fluid-dynamic blade-volute interaction is dominated by the vorticity shedding from blade trailing edge and their impingement on the volute tongue with subsequent cutting and distortion. And high pressure amplitude is generated with the corresponding high vorticity magnitude observed. So the intense interaction between flow structures (jet-wake pattern) and volute tongue is crucial to unsteady pressure pulsation. Thus, to lower pressure pulsation amplitude and fluid dynamic forces, controlling the vortical structure at blade trailing edge is an effective method.

scholarly journals Investigating the In-Flow Characteristics of Multi-Operation Conditions of Cross-Flow Fan in Air Conditioning Systems

Processes ◽  
2019 ◽  
Vol 7 (12) ◽  
pp. 959
Author(s):  
Weijie Zhang ◽  
Jianping Yuan ◽  
Qiaorui Si ◽  
Yanxia Fu
Keyword(s):  
Pressure Distribution ◽  
Flow Rate ◽  
Total Pressure ◽  
Air Conditioning ◽  
Pressure Pulsation ◽  
Flow Characteristics ◽  
Cross Flow ◽  
Operating Conditions ◽  
Aerodynamic Noise ◽  
Cross Flow Fan

Cross-flow fans are widely used in numerous applications such as low-pressure ventilation, household appliances, laser instruments, and air-conditioning equipment. Cross-flow fans have superior characteristics, including simple structure, small size, stable airflow, high dynamic pressure coefficient, and low noise. In the present study, numerical simulation and experimental research were carried out to study the unique secondary flow and eccentric vortex flow characteristics of the internal flow field in multi-operating conditions. To this end the vorticity and the circumferential pressure distribution in the air duct are obtained based on the performed experiments and the correlation between spectral characteristics of multiple operating conditions and the inflow state is established. The obtained results show that when the area of the airflow passage decreases while the area of the eccentric vortex area gradually increases, then the airflow of the cross-flow fan decreases, the outlet expands, and the flow pattern uniformity reduces. It was found that wakes form in the vicinity of the blade and the tail of the volute tongue, which generate pressure pulsation, and aerodynamic noise. The pressure distribution along the inner circumference shows that the total minimum pressure appears in the eccentric vortex near the volute tongue and the volute returns near the zone. Moreover, it was found that the total pressure near the eccentric vortex is significantly smaller than that of the main flow zone. As the flow rate decreases, the pressure pulsation amplitude of the eccentric vortex region significantly increases, while the static and total pressure pulsation amplitudes are gradually increased. Close to the eccentric vortex on the inner side of the blade in the volute tongue area, total pressure is low, total pressure on the outside of the blade is not affected, and pressure difference between the inner and outer sides is large. When the flow rate of the cross-flow fan is 0.4 Qd, there is no obvious peak at the harmonic frequency of the blade passage frequency. This shows that the aerodynamic noise is caused by the main unstable flow.

scholarly journals Effect of Suction and Discharge Conditions on the Unsteady Flow Phenomena of Axial-Flow Reactor Coolant Pump

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1592
Author(s):  
Xin Chen ◽  
Shiyang Li ◽  
Dazhuan Wu ◽  
Shuai Yang ◽  
Peng Wu
Keyword(s):  
Unsteady Flow ◽  
Pressure Pulsation ◽  
Flow Reactor ◽  
Axial Flow ◽  
Hydraulic Performance ◽  
Uniform Flow ◽  
Coolant Pump ◽  
Reactor Coolant ◽  
Flow Phenomena ◽  
Rotating Impeller

In order to study the effects of the suction and discharge conditions on the hydraulic performance and unsteady flow phenomena of an axial-flow reactor coolant pump (RCP), three RCP models with different suction and discharge configurations are analyzed by computational fluid dynamics (CFD) method. The CFD results are validated by experimental data. The hydraulic performance of the three RCP models shows little difference. However, the unsteady flow phenomena of RCP are significantly affected by the variation of suction and discharge conditions. Compared with that of Model E-S (baseline, elbow-single nozzle), the pressure pulsation in rotating frame of Model S-S (straight pipe-single nozzle) and Model E-D (elbow-double nozzles) is weakened in different degrees and forms, due to the more uniform flow fields upstream and downstream of the impeller, respectively. It indicates that the generalized rotor-stator interaction (RSI) actually exists between the rotating impeller and all stationary components causing the circumferentially non-uniform flow. Furthermore, improving the circumferential uniformity of the flow upstream and downstream of impeller (suction and discharge flow) also contributes to reducing the radial dynamic fluid force acting on the impeller. Compared with those of Model E-S, the dynamic FX and FY of Model S-S are severely weakened, and those of Model E-D also gain a minor amplitude decrease at fBPF. In contrast, the general pressure pulsation in fixed frame is mainly related to the rotating impeller and barely affected by the suction and discharge conditions.

Study on pressure pulsation characteristics of reactor coolant pump during the idling transition process

2019 ◽  
Vol 25 (18) ◽  
pp. 2509-2522 ◽  
Author(s):  
Xiuli Wang ◽  
Yonggang Lu ◽  
Rongsheng Zhu ◽  
Yuanyuan Zhao ◽  
Qiang Fu
Keyword(s):  
Pressure Pulsation ◽  
Transient Flow ◽  
Guide Vane ◽  
Transition Process ◽  
Dynamics Simulation ◽  
Discrete Wavelet ◽  
Flow Process ◽  
Coolant Pump ◽  
Rotating Speed ◽  
Reactor Coolant

The idling characteristic of the reactor coolant pump is one of the important indicators for the safe operation of the nuclear power system. The idling transition process of the reactor coolant pump under the power failure accident condition belongs to the transient flow process. During most of the time of the idling transition process, the parameters of flow, rotating speed, and head are all nonlinear changes, and the study of the idling change law is extremely difficult. This paper introduces the nonlinear inertia transient phase of the reactor coolant pump and the principle of wavelet analysis. Based on the experimental results of the idling transition process, the polynomial fitting of the flow curve and the rotating speed curve is fitted, and the idling transient equation is established which is a boundary condition for computational fluid dynamics simulation of the nonlinear idling transient stage of the reactor coolant pump with different types of guide vanes. The signal fluctuation of pressure pulsation time-domain change at the volute outlet in different sub-bands is analyzed by means of a fast, discrete wavelet transform, and the effects of different vane optimizations in different idling stages are analyzed. It was found that the pressure fluctuation amplitude of each sub-frequency range of pump outlet in the model of the shunt guide vane is significantly smaller than that of the normal guide vane.

scholarly journals The Flow Rate Influence on the Interaction of a Radial Pump Impeller and the Diffuser

2004 ◽  
Vol 10 (4) ◽  
pp. 309-317 ◽  
Author(s):  
A. Akhras ◽  
M. El Hajem ◽  
J.-Y. Champagne ◽  
R. Morel
Keyword(s):  
Flow Rate ◽  
Angular Position ◽  
Operating Conditions ◽  
Laser Doppler Velocimeter ◽  
Pump Impeller ◽  
Vaned Diffuser ◽  
Time Resolved ◽  
Flow Investigation ◽  
Rotor Stator Interaction ◽  
Radial Pump

This article presents the results of a detailed flow investigation within a centrifugal pump equipped with a vaned diffuser. The measurements were made with a laser Doppler velocimeter and were carried out at different operating points. The flow was investigated for different rotor–stator relative positions.Unsteady velocity measurements, obtained in phase with the rotor angular position, gave access to the flow inside the impeller channels where three sections were explored. In the diffuser, five sections were studied. Thus, time resolved details of the flow were examined for a better understanding of the complex unsteady flow existing between the two interacting blade rows.Results obtained at different operating conditions show that the rotor-stator interaction is affected by the diffuser position and the flow rate.

Unsteady Pressure Pulsation Measurements and Analysis of a Low Specific Speed Centrifugal Pump

2017 ◽  
Vol 139 (7) ◽  
Author(s):  
Bo Gao ◽  
Pengming Guo ◽  
Ning Zhang ◽  
Zhong Li ◽  
MinGuan Yang
Keyword(s):  
Frequency Band ◽  
Flow Rate ◽  
Pressure Pulsation ◽  
Operating Conditions ◽  
Stable Operation ◽  
Centrifugal Pumps ◽  
Pressure Transducers ◽  
Unsteady Pressure ◽  
Low Specific Speed ◽  
Response Pressure

Intense pressure pulsation, resulted from the flow structure shedding from the blade trailing edge and its interaction with the volute tongue and the casing, is detrimental to the stable operation of centrifugal pumps. In the present study, unsteady pressure pulsation signals at different positions of the volute casing are extracted using high response pressure transducers at flow rate of 0–1.55ΦN. Emphasis is laid upon the influence of measuring position and operating condition on pressure pulsation characteristics, and components at the blade passing frequency fBPF and root-mean-square (RMS) values in 0–20.66fn frequency band are mainly analyzed. Results clearly show that the predominant components in pressure spectra always locate at fBPF. The varying trends versus flow rate of components at fBPF differ significantly for different points, and it is considered to be associated with the corresponding flow structures at particular positions of the volute casing. At the near-tongue region, high pressure amplitudes occur at the position of θ = 36 deg, namely the point at the after tongue region. For different measuring points, angular distributions of amplitudes at fBPF and RMS values in 0–20.66fn frequency band are not consistent and affected significantly by the pump operating conditions.

Study on the Four-Quadrant Homologous Characteristic and Two-Phase Flow Head Degradation of a Reactor Coolant Pump

2021 ◽  
Vol 143 (4) ◽  
Author(s):  
Bin Huang ◽  
Meimei Zhang ◽  
Kexin Pu ◽  
Peng Wu ◽  
Dazhuan Wu
Keyword(s):  
Two Phase Flow ◽  
Operating Conditions ◽  
Entropy Generation Rate ◽  
Phase Flow ◽  
Two Phase ◽  
Coolant Pump ◽  
Reactor Coolant ◽  
Rate Analysis ◽  
Four Quadrant ◽  
Flow Head

Abstract This paper studies the four-quadrant homologous characteristic and analyzes the gas–liquid two-phase flow head degradation of ACP100 reactor coolant pump. The theoretical basis and the operating conditions of the pump's four-quadrant homologous characteristic are introduced. To verify the reliability of the computational fluid dynamics (CFD), the comparison of the results from CFD and test is implemented, and with these datum for the pump is plotted with homologous curves. In this paper, homologous pump characteristics are used to make the proper estimation on complete characteristic outside the testing range. Meanwhile, a combined method of impeller Euler head distribution and entropy generation rate analysis are applied for the head degradation of ACP100 reactor coolant pump under gas–liquid two-phase flow condition, and 70% of gas void fraction (GVF) is shown as the maximum degradation point. In addition, head degradation multiplier plots homologous curves are used to predict the homologous characteristic of specific GVF.

Numerical Investigation of Transient Flow in a Prototype Centrifugal Pump during Startup Period

2017 ◽  
Vol 34 (2) ◽  
Author(s):  
Yu-Liang Zhang ◽  
Zu-Chao Zhu ◽  
Hua-Shu Dou ◽  
Bao-Ling Cui ◽  
Yi Li ◽  
...  
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Transient Flow ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Transient Performance ◽  
Pipe System ◽  
Incompressible Viscous Flow ◽  
Rotor Stator Interaction ◽  
Startup Period

AbstractTransient performance of pumps during transient operating periods, such as startup and stopping, has drawn more and more attentions recently due to the growing engineering needs. During the startup period of a pump, the performance parameters such as the flow rate and head would vary significantly in a broad range. Therefore, it is very difficult to accurately specify the unsteady boundary conditions for a pump alone to solve the transient flow in the absence of experimental results. The closed-loop pipe system including a centrifugal pump is built to accomplish the self-coupling calculation. The three-dimensional unsteady incompressible viscous flow inside the passage of the pump during startup period is numerically simulated using the dynamic mesh method. Simulation results show that there are tiny fluctuations in the flow rate even under stable operating conditions and this can be attributed to influence of the rotor–stator interaction. At the very beginning of the startup, the rising speed of the flow rate is lower than that of the rotational speed. It is also found that it is not suitable to predict the transient performance of pumps using the calculation method of quasi-steady flow, especially at the earlier period of the startup.

Advancement of Reactor Coolant Pump (RCP) Performance Verification Test in KAERI

2014 ◽  
Author(s):  
Yun-Je Cho ◽  
Yeon-Sik Kim ◽  
Seok Cho ◽  
Seok Kim ◽  
Byoung-Uhn Bae ◽  
...  
Keyword(s):  
Flow Rate ◽  
Performance Test ◽  
Pressure Pulsation ◽  
Test Facility ◽  
Working Fluid ◽  
Production Test ◽  
Test Results ◽  
Flow Meter ◽  
Reactor Coolant ◽  
Type Test

Korea Atomic Energy Research Institute (KAERI) has designed and constructed a test facility for reactor coolant pumps (RCPs). The RCP Test Facility (RCPTF) has the capability to test a RCP under the operation condition of an Advanced Power Reactor 1400 MW (APR1400). The design values of the facility are 17.2 MPa, 343 °C, 11.7 m3/s, and 13 MW in maximum pressure, temperature, flow rate, and electrical power, respectively. In the facility, it is possible to perform a type test for a newly-developed RCP as well as a production test for a RCP before its installation in a nuclear power plant. For the production test, H-Q curves under the cold and hot conditions are acquired. For the type test, various transient tests are additionally performed including four types of seal transient tests, a thrust bearing transient test, a cost down test, and so on. To acquire H-Q curves of a RCP, the flow rate should be controlled by varying the flow resistance in the test loop. The RCPTF uses a Variable Restriction Orifice (VRO) whose flow area can be controlled by moving the two orifice plates installed in-parallel. The need for flow control valves and bypass lines was eliminated using the VRO such that the flow disturbance was minimized. The flow rate in the main loop of the RCPTF is measured by a standard venture flow meter. The flow rate in the RCPTF is very high and thus the venture flow meter could not be calibrated in the entire range of Reynolds number corresponding to the operating condition in the APR1400. The calibration was conducted at the Colorado Experiment Engineering Station Inc. (CEESI) in the USA where natural gas is used for a working fluid. If a discharge coefficient calibrated with the gas is applied in the test results performed using the water as a working fluid, a discrepancy can occur due to the static hole error. Therefore, the static hole error was compensated in the test results and the result shows the improvement. The effect of the temperature on the pressure pulsation amplitude was also evaluated. During a cold performance test and heat-up phase to the condition of a hot performance test, an abnormal increase in the pressure pulsation amplitude was observed near the specific temperature range. This is acoustic resonance phenomena that occur when a blade passing frequency of the RCP is proportional to the harmonic resonance frequency of the RCPTF.

scholarly journals Influence of Circumferential Placement Position of Guide Vanes on Performance and Dynamic Characteristics of Nuclear Reactor Coolant Pump

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Xiaorui Cheng ◽  
Boru Lv ◽  
Chenying Ji ◽  
Ningning Jia ◽  
Dorah N
Keyword(s):  
Nuclear Reactor ◽  
Guide Vane ◽  
Equivalent Stress ◽  
Hydraulic Loss ◽  
Stress Strain ◽  
Coolant Pump ◽  
Guide Vanes ◽  
Reactor Coolant ◽  
Maximum Equivalent Stress ◽  
Exit Edge

In order to study the influence of the circumferential placement position of the guide vane on the flow field and stress-strain of a nuclear reactor coolant pump, the CAP1400 nuclear reactor coolant pump is taken as the research object. Based on numerical calculation and test results, the influence of circumferential placement position of the guide vane on the performance of the nuclear reactor coolant pump and stress-strain of guide vanes are analyzed by the unidirectional fluid-solid coupling method. The results show that the physical model and calculation method used in the study can accurately reflect the influence of the circumferential placement position of the guide vane on the nuclear reactor coolant pump. In the design condition, guide vane position has a great influence on the nuclear reactor coolant pump efficiency value, suction surface of the guide vane blade, and the maximum equivalent stress on the hub. However, it has a weak effect on the head value, pressure surface of the guide vane blade, and the maximum equivalent stress on the shroud. When the center line of the outlet diffuser channel of the case is located at the center of the outlet of flow channel of the guide vane, it is an optimal guide vane circumferential placement position, which can reduce the hydraulic loss of half of the case. Finally, it is found that the high stress concentration area is at the intersection of the exit edge of the vane blade and the front and rear cover, and the exit edge of the guide vane blade and its intersection with the front cover are areas where the strength damage is most likely to occur. This study provides a reference for nuclear reactor coolant pump installation, shock absorption design, and structural optimization.

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