Validation of ATHLET Code by LOCA-Induced Pressure Wave Propagation Tests

2014 ◽  
Author(s):  
István Trosztel ◽  
Iván Tóth ◽  
György Ézsöl
Keyword(s):  
Wave Propagation ◽  
Flow Rate ◽  
Pressure Wave ◽  
High Speed ◽  
Low Frequency ◽  
Test Facility ◽  
Primary System ◽  
Pressure Waves ◽  
Test Results ◽  
System Pressure

Propagation of pressure waves inside the reactor vessel after a large break LOCA is an issue since it affects pressure drop across core internals and, as a result, induces stresses in different components, like core barrel, core structures and even fuel. For reactor safety analysis pressure wave propagation is traditionally performed by systems codes. However, strong dispersion among the calculated results calls for test results to validate the calculations. The pressure wave propagation following a larger LOCA is being systematically addressed by experiments in the PMK-2 integral-type test facility. In order to capture the high speed propagation of pressure waves special pressure transducers (capable to resolve the pressure variation with a frequency of 4 kHz) have been installed. The first four tests were conducted with rupture disks for opening the break, but a special quick opening valve will be installed for future tests, allowing the adjustment of the opening time between 12 and 50 ms. The paper presents results of validation of the ATHLET code by the test results. The low-frequency oscillation of the measured system pressure was shown to be caused by flow rate coming from the pressuriser that compensates mass lost via the break: the frequency of the oscillation was slightly under-predicted. The propagation of the first rarefaction wave from the top of the downcomer to the upper plenum is very well calculated by ATHLET: in spite of the first order discretisation no numerical diffusion can be observed. The calculated pressure differences between two different locations in the system are of primary interest, since they define the loads on primary system internals. ATHLET somewhat overestimates the amplitude of the pressure difference pulses, while it fairly well describes the frequency of oscillations. First analyses indicate an effect of the calculated break flow rate. ATHLET calculates a slower attenuation of the pressure oscillations as compared to test results. This can be the consequence of rigid walls assumed in the analysis. The tendency of increasing first pressure peak with increasing system pressure is well predicted by the code. In summary, it can be stated that ATHLET calculations produce slightly conservative results based on comparison with measured data.

Characteristics of pressure-wave propagation in a compliant tube with a fully collapsed segment

1985 ◽  
Vol 158 ◽  
pp. 113-135 ◽  
Author(s):  
Masashi Shimizu
Keyword(s):  
Wave Propagation ◽  
Wave Front ◽  
Flow Rate ◽  
Pressure Wave ◽  
High Speed ◽  
Wave Reflection ◽  
Positive Pressure ◽  
Rubber Tube ◽  
Korotkoff Sound ◽  
Steep Wave

In order to model the fluid dynamics of Korotkoff sound generation when the artery under the cuff is fully collapsed during most of the heart cycle, the characteristics of pressure-wave propagation in a long silicone-rubber tube were studied experimentally. The central portion of this tube was designed to collapse to zero cross-sectional area as a result of high negative transmural pressure, thus simulating a collapsed artery. Propagation of a single half-sinusoidal pressure wave in and around this segment was studied in detail by pressure, velocity and tube-longitudinal-shape measurements.A very steep wave front (shock wave) capable of producing a short tapping sound was formed by an overtaking phenomenon in the fully collapsed tube segment and it propagated into the inflated tube distal to the collapsed segment. An empirical equation relating the flow rate penetrating into the collapsed segment, the incident-wave pressure and the external pressure Pc over the collapsed segment was obtained. This equation predicts that the pressure-wave propagation in a fully collapsed segment depends only on the flow rate into the collapsed segment.The initial internal pressure of the tube distal to the collapsed segment Pd is one independent variable in the high-cuff-pressure condition. The amplitude of the steep wave front and the shape of the pressure wave in the inflated tube distal to the collapsed segment are governed by Pc–Pd and the flow rate penetrating the collapsed segment. For the same flow rate, if Pc–Pd is lower than a critical value, the amplitude of the pressure in the distal tube decreases with increasing Pd because of positive pressure-wave reflection at the exit of the collapsed segment. On the other had, if Pc–Pd is higher than that value, no wave reflection occurs and the amplitude of the pressure wave is independent of Pd. In the latter case a severe constriction exists near the distal end of the collapsed segment, and flow occurs as two thin high-speed jets.

Active Attenuation of Low Frequency Noise Radiated from Tunnel Exit of High Speed Train

1994 ◽  
Vol 13 (2) ◽  
pp. 39-47
Author(s):  
Min Liang ◽  
Toshiya Kitamura ◽  
Katsushi Matsubayashi ◽  
Toshifumi Kosaka ◽  
Tatsuo Maeda ◽  
...  
Keyword(s):  
Pressure Gradient ◽  
Pressure Wave ◽  
High Speed ◽  
Outer Space ◽  
Low Frequency ◽  
Close Relation ◽  
Frequency Noise ◽  
High Speed Train ◽  
Low Frequency Noise ◽  
Active Cancellation

A pressure wave occurs at the instant when a high speed train enters into a long tunnel. The wave propagates downstream to the tunnel exit and low frequency noise is radiated from the exit to outer space. The low frequency noise causes a lot of problems1 to the residents living near the exit and has a close relation with the pressure gradient of the pressure wave. To attenuate the low frequency noise, an active cancellation system rather than a passive one is developed. This research uses a model tunnel to examine the characteristic of the pressure wave and investigates the possibility to reduce the low frequency noise by reducing the pressure wave gradient with active cancellation.

Growth of Flame Front Turbulence

1986 ◽  
Vol 108 (4) ◽  
pp. 877-881 ◽  
Author(s):  
T. Tsuruda ◽  
M. Harayama ◽  
T. Hirano
Keyword(s):  
Experimental Study ◽  
Combustion Chamber ◽  
Flame Front ◽  
Pressure Wave ◽  
High Speed ◽  
Wall Turbulence ◽  
Pressure Waves ◽  
Fuel Type ◽  
Fuel Concentration ◽  
Schlieren Photography

An experimental study was performed on the growth of flame front turbulence by stimulating a laminar propagating flame with weak pressure waves, which were generated by sudden breaking of the membrane separating a small chamber from the combustion chamber. The flame front behavior was explored by using high-speed schlieren photography. About one millisecond after the first weak pressure wave passed the flame front, a very fine disturbance appeared at the central part of the flame front, where no effect of the wall turbulence could appear. Then, the area and strength of the disturbance were observed to increase rapidly. The effects of the pressure wave intensity, fuel concentration, and fuel type on the growth of this type of flame front turbulence were examined in detail.

ROSA/LSTF Experiment on a PWR Station Blackout Transient With AM Measures and RELAP5 Post-Test Analysis

2014 ◽  
Author(s):  
Takeshi Takeda ◽  
Iwao Ohtsu ◽  
Taisuke Yonomoto
Keyword(s):  
Flow Rate ◽  
Large Scale ◽  
Heat Removal ◽  
Sensitivity Analyses ◽  
Test Facility ◽  
Primary System ◽  
Energy Agency ◽  
Coolant Injection ◽  
Station Blackout ◽  
Secondary Side

An experiment on a PWR station blackout transient with the TMLB’ scenario and accident management (AM) measures was conducted using the ROSA/large scale test facility (LSTF) at Japan Atomic Energy Agency under an assumption of non-condensable gas inflow to the primary system from accumulator (ACC) tanks. The AM measures proposed in this study are steam generator (SG) secondary-side depressurization by fully opening the safety valves in both SGs with the start of core uncovery and coolant injection into the secondary-side of both SGs at low pressures. The LSTF test revealed the primary pressure started to decrease when the SG primary-to-secondary heat removal resumed soon after the coolant injection into the SG secondary-side. The primary depressurization worsened due to the gas accumulation in the SG U-tubes after the completion of ACC coolant injection. The RELAP5 code predicted well the overall trend of the major phenomena observed in the LSTF test, and indicated remaining problems in the predictions of SG U-tube collapsed liquid level and primary mass flow rate after the gas ingress. The SG coolant injection flow rate was found to affect significantly the peak cladding temperature and the ACC actuation time through the RELAP5 sensitivity analyses.

An Investigation Into Quantifying Pressure Wave Oscillation in the Lung

2010 ◽  
Author(s):  
J. Mussa ◽  
A. M. Al-Jumaily ◽  
G. Ijpma
Keyword(s):  
Wave Propagation ◽  
Medical Devices ◽  
Pressure Wave ◽  
Pressure Oscillation ◽  
Variable Pressure ◽  
Pressure Waves ◽  
Pressure Oscillations ◽  
Wave Oscillation ◽  
Airway Tree

Understanding pressure wave propagation in the lung is of importance for a number of medical devices including those for diagnostics and treatments. The main objective of this research is to quantify the transmitability of the airway tree with respect to pressure oscillations. Ovine lungs are casted to produce a hollow airway tree. Variable pressure oscillations and airflow are supplied at the trachea of the casted model and pressure oscillations are measured at the bronchioles. The study indicates that pressure waves with different frequencies can be delivered to different locations of the lung by controlling the pressure oscillation source to the lung.

An Investigation Into the Characteristics of a “2D” Flow Control Valve

2000 ◽  
Author(s):  
J. Ruan ◽  
R. Burton ◽  
P. Ukrainetz
Keyword(s):  
Flow Control ◽  
Flow Rate ◽  
High Speed ◽  
Structural Parameters ◽  
Control Valve ◽  
Favorable Effect ◽  
Flow Control Valve ◽  
System Pressure ◽  
Hydrostatic Force ◽  
2D Flow

Abstract In hydraulic servo systems, a pilot stage is often used to reduce the influence of Bernoulli’s forces and frictional forces when trying to accurately position a spool. A unique pilot controlled valve, (defined as a “2D” flow control valve), which utilizes both rotary and linear motions of a single spool, is presented. The rotary motion uses a spiral groove in the sleeve combined with high and low pressure holes on the spool land to control the pressure in the spool chamber, while the linear motion of the spool is actuated by a hydrostatic force. Both linear theory and numerical simulation are adopted in the investigation of the characteristics of the valve. A criterion for stability is established from a linearized model of the valve. The analysis establishes the effects that certain structural parameters have on the valve’s static and dynamic characteristics. Special experimental procedures were designed to obtain properties such as mechanical stiffness, leakage flow rate, and dynamic response under different structural parameters and system pressure. It was shown that the leakage through the spool-sleeve clearance had a favorable effect on the valve stability. Theoretical and experimental results show that it is necessary to establish a balance between the static and dynamic performance in establishing appropriate structural parameters. It is also shown that the 2D flow control valve can demonstrate a high speed of response, while maintaining the pilot flow rate at a low level.

scholarly journals Experimental Study of Thermo-Acoustic Instability Triggering in a Staged Liquid Fuel Combustor Using High-Speed OH-PLIF

2017 ◽  
Author(s):  
Antoine Renaud ◽  
Shigeru Tachibana ◽  
Shuta Arase ◽  
Takeshi Yokomori
Keyword(s):  
Flow Rate ◽  
High Speed ◽  
Pressure Fluctuations ◽  
Low Frequency ◽  
Frequency Change ◽  
Main Stage ◽  
Fuel Flow Rate ◽  
Acoustic Instability ◽  
Driving Mechanisms ◽  
Fuel Flow

A staged injector developed by JAXA and fueled with kerosene is studied in a high-pressure combustion experiment. With a stable pilot fuel flow rate, the fuel flow rate in the main stage is progressively increased. A high-speed OH-PLIF system is used to record the flame motion at 10,000 fps. In the beginning of the recording, POD modes shows that the flame behavior is dominated by relatively low-frequency rotation due to the swirling motion of the flow. These rotational motions then coexist with a thermo-acoustic instability around 475 Hz which increases the amplitude of the pressure fluctuations inside the chamber. DMD analyses indicate that this instability is associated with a widening of the flame occurring when the pressure fluctuations are the highest, giving the instability a positive feedback. The instability frequency then abruptly switches to 500 Hz while retaining the same driving mechanisms. Potential candidates for this frequency change are proposed.

Propagation velocity and reflection of pressure waves in the canine coronary artery

1979 ◽  
Vol 237 (4) ◽  
pp. H469-H474 ◽  
Author(s):  
T. Arts ◽  
R. T. Kruger ◽  
W. van Gerven ◽  
J. A. Lambregts ◽  
R. S. Reneman
Keyword(s):  
Coronary Artery ◽  
High Frequency ◽  
Pressure Wave ◽  
Pressure Pulse ◽  
Peripheral Resistance ◽  
Low Frequency ◽  
Pressure Waves ◽  
Cross Sectional ◽  
Frequency Components ◽  
Canine Coronary Artery

In this study the pressure wave velocity in the anterior descending branch of the left coronary artery (LADC) of the dog was measured by determining the delay time between pressure pulses along this artery. This method can only be applied if reflections of the pressure wave distal to the sites of pressure measurement are insignificant. From araldite casts of the coronary arteries the following relation between the diameter proximal to (dprox) and distal to (ddist 1, ddist 2) a bifurcation was found: dprox2.55 = ddist12.55 + ddist 22.55, indicating that reflections at a bifurcation areminimal. In dogs reflections were studied by inducing during diastole a pressure pulse in the aorta and measuring pressure and volume flow proximal to and pressure distal to a segment of the LADC at various levels of the coronary peripheral resistance. Reflection of high-frequency components (greater than 7 Hz) was found to be insignificant, allowing application of the above-mentioned method for measuring the wave-front velocity, which is insensitive to low-frequency reflection. At a pressure in the LADC of 13.3 kPa this velocity was 8.6 +/- 1.4 m.s-1 (mean +/- SD). The calculated dynamic cross-sectional stiffness (deltaP/(deltaA/A)) of the LADC was 97 +/- 11 kPa (mean +/- SE) at an arterial pressure of 13.3 kPa.

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.

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