Water Hammer Effect Research Articles

Titanium surface roughening with ultrasonic pulsating water jet

Biomedical industries are looking for natural ways of processing biocompatible materials to improve their biological performances. One untested option is the use of the water hammer effect in the form of water droplets; this can create surfaces with high degrees of capillary elevation whose structures resemble a trabecular structure. In this study, we analyzed the modified surface morphologies and integrity of the titanium alloy Ti6Al4V using water droplet impingement generated with an ultrasonic pulsating water jet at starting frequencies of f = 20 kHz and 40 kHz. The water droplets were distributed along a linear offset trajectory. Two transition methods for producing modified surface morphologies were compared, one with a single transition and another with an additional secondary transverse transition. The created surfaces were classified according to the area surface roughness parameters, Sa and Sz. The results were compared with a control group of samples exposed to a continuous jet with ff = 0 Hz. By setting the technological parameters of an ultrasonic pulsating water jet, the aim was to create surface properties that increased biological interactions during osseointegration. The results positively support the initial indications that the pulsating water jet surface treatment was a more advantageous alternative than other techniques based on using solid particles for surface erosion, whose artifacts can become lodged in the material and contaminate surfaces.

An enhanced dynamic soft sensor–based online estimation of missing data for water distribution system with inherent disturbances

Interruption of water supply is an unfavourable event in water distribution system (WDS). The interruptions are mainly due to water hammer (WH) transients that are caused by sudden pump/valve failures. In this paper, the effects of hammer are mathematically realized considering the effect of valve coefficient integrated with the system. Due to economic and technical limitations, the system is generally equipped with some obsolete instruments for continuous monitoring, which creates a missing data problem. The problem of missing data estimation could be addressed using a novel customized Kalman filter (CKF), a customized version of conventional Kalman filter (KF) based on process model. Initially, to avoid the intricacies of obtaining the optimal estimates of missing instants, the vacancies in the data are filled assigned by the average values of available adjacent data. The measured quantities are considered distorted with state-, input-dependent and independent uncertainties. The effect of WH on a prototypical WDS is studied for different modes of operation, and the missing data points are reconstructed for regular and irregular sampled data set using the proposed CKF. The performance of the proposed algorithm is also compared with the conventional extended Kalman filter (EKF). The study indicates that the proposed missing data estimation algorithm is highly reliable to identify the missing instances in the states of distribution system.

Experimental study on fracture propagation and induced earthquake reduction by pulse hydraulic fracturing in shale reservoirs

Large-scale and complex cracks have always been the eternal goal of hydraulic fracturing (HF) technology in shale reservoirs, but there has been the public concern that the HF could trigger earthquake disasters. It is urgent to develop the new HF technology that can generate a large number of complex cracks and reduce the risk of induced earthquake. Herein, the fracture propagation, fluid pressure distribution and acoustic emission (AE) energy of four types of hydraulic fracturing are analyzed through laboratory experiment and numerical simulation in this study. The new rectangular pulse HF is proposed. It is concluded that the pulse HF with higher fluid pressure gradient takes a shorter time to fracture shale. It is easier to form complex cracks. Relying on reciprocating impact and strong “Water Hammer Effect”, the pulse HF can form a large number of micro-cracks and reduce the energy released at the moment of complete failure of shale. The research shows that the pulse HF with the larger pressure gradient performs better in fracturing shale and reducing the risk of induced earthquake. The rectangular pulse HF has more significant advantages than the sine and triangle pulse HF. It relies on low instantaneous rock rupture energy, long rupture time and widely distributed low energy rupture events to reduce induced earthquakes. These can help to develop the pulse HF technology and reduce the risk of induced earthquakes for shale gas exploitation.

An investigation of data analysis method for hydraulic fracturing based on the water hammer effect

Hydraulic fracturing plays a crucial role in the development of unconventional resources, and assessing fracture geometry is a fundamental aspect of hydraulic fracturing analysis. Among the various technologies for evaluating fracture geometry, the water percussion signal-based method has gained popularity due to its cost-effectiveness, convenience, and real-time capabilities. In this study, we present a methodology for analyzing fracture data that utilizes the water percussion effect. By leveraging the impact of fractures on water percussion pressure attenuation, we propose an inverse calculation approach to determine fracture geometry. Firstly, we introduce the RCI (Reservoir-Completion-Interaction) circuit model, which effectively addresses the bottom hole fracture boundary and simulates the variation of water percussion pressure in the wellbore. Secondly, the simulation results are utilized in an iterative process to determine the RCI values, which are then utilized for the inversion calculation of fracture geometry. Finally, we apply this method to a field case and compare the simulation results with microseismic monitoring data. A larger resistance (R) value indicates a smaller fracture volume, while the (C) value can be used to monitor any poorly performing stages of the fracturing simulation process. The (I) value primarily affects the parameter calculation of the fracture size, especially the fracture width. The results of the field application show that the accuracy rate exceeding 80%, validating the reliability of the model and providing a valuable reference for field fracturing data analysis.

Geolocalization of water-waves origin within water distribution networks using time reversal of first event detection

Drinking water distribution networks in urban areas are daily subject to fast propagating pressure waves resulting from routine operations. These water-hammer waves lead to structural aging and facility damages, the origin of which is not easy to find but are sometimes of high managerial interest. In this contribution, we demonstrate that using a reasonable number of high-frequency pressure detectors distributed within the network combined with a proper post-processing method permits a close geolocalization of the damaging wave origin. The method is first tested and validated on a real water distribution network having approximately 26000 pipes, whereas considering a known, prescribed waveorigin, so that the sensitivity to sensor number (sensor spatial density), sensor location and signal-to-noise ratio on the geolocalization robustness are analyzed in detail. It is then applied and illustrated over real sensor recordings the result of which are validated on the field from history matching. This paper thus presents the first field-scale geolocalization of water-hammer events origin test as well conditions for which, given sensor density and signal-to-noise ratio, the geolocalization success is to be expected.

Status of Research on Water Hammer Effect in Long Distance Pressure Pipelines

In the long distance pressure pipeline, the sudden change of instantaneous pressure caused by the rapid change of liquid velocity is called water hammer, which seriously threatens the safe operation of hydropower station. In this paper, the development and calculation methods of transient flow percussion theory are introduced, and different models and numerical methods are analyzed and compared. Finally, the problems in transient flow research and water hammer prevention measures are summarized, which is helpful to reduce the occurrence of water hammer accidents and guarantee the normal and stable operation of water supply pipeline system. This conclusion can provide reference for water hammer protection of long distance water supply system.

Modeling of water hammer effect during the single cavitating bubble oscillation

The paper presents the results of an analytical study of the vapor-gas bubble dynamics in cavitation processes, giving consideration to the liquid compressibility. The study is based on the concept that cavitation effects are directly related to the occurrence of hydraulic shock on the surface of an extremely compressed bubble. The purpose of this work is to study cavitation bubble dynamics accounting for the spherical water hammer effects. An equation for the bubble dynamics was obtained, which includes the coefficient of liquid adiabatic compressibility as a basic parameter that is directly related to the liquid compressibility. For this equation reduces to the classical Rayleigh-Plesset equation for incompressible liquids. The results of a computational experiment performed within the framework of the modified model are presented for which the behavior of a cavitation bubble both in compressible and in incompressible water was analyzed. Based on a detailed analysis of the results obtained, it is shown that over time .the compressed bubble is in the state of a supercritical fluid with temperature up to 2000 K and pressure of about 400 MPa. The potential energy of the compressed liquid, in the form of a powerful acoustic pulse, emitted by the bubble at the stage of its collapse, is irreversibly dissipated in the surrounding liquid.

Stress Characteristic Analysis of Pump-Turbine Head Cover Bolts during Load Rejection Based on Measurement and Simulation

It is not uncommon for pump-turbine units in pumped storage power plants to experience load rejections due to the sudden disconnection of the generator from the power grid. Load rejection can suddenly increase the rotating speed of the pump-turbine and cause strong pressure fluctuations in the flow passage of the pump-turbine unit. During load rejection, the strong pressure fluctuations caused by the water hammer effect can cause strong structural vibrations, high stresses and even damage to the turbine runner, head cover, stay ring, bottom ring, head cover bolts and bottom ring bolts. In order to study, in detail, the flow-induced stress characteristics of the prototype pump-turbine unit, and the pressure variations during load rejection in a high-head pumped storage power plant were measured first. Then the measured data were used to set up computational fluid dynamics (CFD) simulations in the entire flow passage of the prototype pump-turbine and to calibrate the simulation results. The calculated pressure distributions in the flow passage during load rejection were exported and mapped on the finite element model of the stationary structures of the pump-turbine unit so that the flow-induced stresses on the head cover, stay ring, bottom ring, head cover bolts and bottom ring bolts can be calculated. The results of the analysis show that the maximum stresses in the head cover bolts and bottom ring bolts are located on the rounded corner of the bolt near the stay ring and that the stresses in the bolts vary with time during load rejection. The maximum stresses of the head cover bolts are higher than the maximum stresses of the bottom ring bolts, and the maximum stresses of the bolts are above two-thirds of the yield strength of the bolt material. It is recommended to use larger nominal diameter bolts to avoid damage to the connecting bolts of the pump-turbine unit.

Location estimation of subsurface fluid-filled fractures: Cepstral predominant peak analysis and numerical study

In various subsurface resource development or fluid piping transportation problems, subsurface fluid-filled fractures often appear. Fracture location determination has always been critical in the related fields. Acoustic wave reflection at the junction and boundary in the pipeline can carry information about the property of the system. By using the accompanying acoustic wave information combined with the water hammer effect, the location of subsurface fractures can be estimated. A numerical fluid flow model for instantaneous shut-in is presented based on the water hammer effect. Fluid penetration effects, wellbore storage effect, and fluid inertial effect are considered. A method for determining the locations of subsurface fractures using cepstral predominant peak (CPP) is first proposed. By cepstral, we mean the inverse Fourier transform of the logarithm of the estimated signal spectrum. Also, the relationship between instantaneous shut-in pressure and cepstrum response is investigated in detail. To improve the robustness, CPP analysis based on Kaiser windowed cepstrum is used to identify the impulse period of fracture. Compared with the original cepstrum, Kaiser windowed cepstrum has the better performance for CPP analysis. The proposed flow model is impactful as it can provide pressure data with known fracture locations. Meanwhile, the data can be used to optimize and examine the performance of CPP analysis with Kaiser windowed cepstrum. A field experiment is conducted to validate the analysis about the acoustic wave in a pipeline system with fractures. By installing a high-frequency pressure monitoring device at the pump, the actual instantaneous shut-in pressure for an oil well is obtained. The experiment results show that the CPP analysis can obtain the fracture location efficiently and accurately, which can provide insights for engineering practices.

On the critical pressure pulse width for ignition of hydrogen–air and dimethyl ether–air mixtures

Under certain situations, such as a water hammer event, a volume of gas can undergo a rapid compression immediately followed by a rapid expansion, which could lead to auto-ignition under certain conditions. The goal of the present study was to investigate under which critical conditions such a pressure pulse could lead to an ignition event. To simulate the pressure pulse, a simplified Gaussian pressure pulse model was implemented in Cantera. Hydrogen–air and dimethyl ether–air mixtures were employed to study the ignition dynamics of chemical systems with a single and a double step of heat release. The numerical simulations were performed for three peak pressures of 101.3, 1013.2, and 5066 kPa, for a range of compression ratios between 5 and 45, and various pulse widths, which determine the characteristics of the pressure pulse. Depending on the width of the Gaussian pulse, either ignition or chemical quenching were observed. Critical ignition, just at the limit between ignition and quenching, is the result of the competition between chemical reaction and volumetric expansion due to the imposed specific volume changes. This competition can be summarized by the concept of critical pressure pulse width, which is an extension of the critical decay rate concept. To further investigate the mechanisms responsible for critical ignition and quenching, quantitative thermo-chemical analyses were performed for sub-critical, critical and super-critical conditions. A Damköhler number was defined as the ratio of characteristic time of expansion to ignition delay time to characterize the competition between ignition and quenching. A simplified non-dimensional pressure pulse model for which the derivative of the naperian logarithm of density was assumed to follow a linear law was established. It can be employed to derive the critical conditions for which ignition fails. The evolution of non-dimensional temperature was obtained numerically and showed the existence of a critical pulse width for successful ignition and that the location of ignition delay time moves from the expansion phase to the compression phase as the non-dimensional pulse width is increased.

Design of the Cooling Water System for the EAST Lower Divertor

The new lower tungsten divertor is a crucial component to achieve the targets of long pulse and high <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\beta $ </tex-math></inline-formula> H-mode operation of Experimental Advanced Superconducting Tokamak (EAST) device. The cooling water system (CWS) of lower divertor should have sufficient heat removal capability and be able to cope with pressure transients caused by the potential water hammer events, which makes the design challenging. In this study, the system process and details of main component are determined based on the design requirements. The thermal-hydraulic analysis model has been developed by Flowmaster (FLOWMASTER) to conduct the heat transfer analysis. Furthermore, the system water hammer transients under one pump trip condition have been analyzed. The results show that the flow distribution of each client is uniform, and the pressure and temperature of key points meet the design requirements. The maximum pressure fluctuation, 0.16 MPa, caused by the sudden closing of the check valve is within the acceptable range. The experiment data are in good agreement with the simulation values, which proves the correctness of the model and the feasibility of the design.

Dynamic Simulation of Starting and Emergency Conditions of a Hydraulic Unit Based on a Francis Turbine

The Francis hydro-turbine is a typical nonlinear system with coupled hydraulic, mechanical, and electrical subsystems. It is difficult to understand the reasons for its operational failures, since the main cause of failures is due to the complex interaction of the three subsystems. This paper presents an improved dynamic model of the Francis hydro-turbine. This study involves the development of a nonlinear dynamic model of a hydraulic unit, given start-up and emergency processes, and the consideration of the effect of water hammer during transients. To accomplish the objectives set, existing models used to model hydroelectric units are analyzed and a mathematical model is proposed, which takes into account the dynamics during abrupt changes in the conditions. Based on these mathematical models, a computer model was developed, and numerical simulation was carried out with an assessment of the results obtained. The mathematical model built was verified on an experimental model. As a result, a model of a hydraulic unit was produced, which factors in the main hydraulic processes in the hydro-turbine.

Study on the Influence of Overflow Well Shut-In Mode on Wellbore Pressure Distribution in Ultradeep Wells

Summary With the deepening of exploration and development of oil and gas resources, more complex oil and gas reservoirs have been found, and oil and gas well drilling has gradually developed to ultradeep (&amp;gt;8000 m). In the oil and gas exploration and development of deep and ultradeep wells, a small-size borehole is usually used to uncover the target layer. In the drilling stage, the annular space gap of slimhole construction is small, the pressure difference is large, and the tripping fluctuation pressure is large; therefore, overflow is easy to occur. Because the upward channeling speed after overflow is fast, the pressure fluctuation caused by shut-in is large, and the requirements for well control are high, making it very important to study the shut-in mode after drilling overflow and the fluctuation of annulus pressure to ensure the safety of ultradeep well drilling. However, the current research on shut-in mode only focuses on changing the length of shut-in time and does not consider the operation steps of closing different components. It is obviously not rigorous to simplify semisoft shut-in and soft shut-in into a hard shut-in process with a long time. In this paper, the pressure wave velocity model and transient flow model of multiphase flow in the annulus are established. The shut-in process of different wellhead components is considered for the first time, the corresponding wellhead opening function is constructed, and the effects of different well shut-in methods on annulus pressure distribution and water hammer effect are studied. Some conclusions can be drawn: The annulus pressure wave velocity aam decreases rapidly with the increase of void fraction and decreases gradually with the increase of solid particle concentration. After hard shut-in, the wellhead pressure increases rapidly and fluctuates periodically. The shorter the shut-in time, the greater is the wellhead pressure. The displacement of drilling fluid has little influence on the pressure peak but has a great influence on the amplitude of pressure fluctuation. When the annulus pressure rises, the casing bulges outward to produce additional tension, while the drillpipe shrinks inward to produce additional pressure. When the annulus pressure drops, the casing shrinks inward to produce additional pressure, while the drillpipe bulges outward to produce additional tension. During soft shut-in, the closing time of the blowout preventer (BOP) has a great impact on the annulus pressure of the wellhead. When the shut-in time is short, the pressure rises instantaneously and fluctuates violently and the cycle is short; during semisoft shut-in, the larger the opening of the throttle valve, the smaller is the fluctuating pressure of the wellhead when the BOP is closed. When the throttle valve is closed after the BOP is closed, then the larger the opening of the throttle valve, the greater will be the fluctuating pressure. With the calculation and discussion of wellbore stress distribution during shut-in of an overflow well in this paper, we hope to provide reference for two groups of people mainly. For one thing, it can offer a new idea, calculation method, and meaningful conclusion to other researchers who are studying in this area. For another, it will help engineers making decisions when overflow occurs.

Water hammer issues in refurbishment of a high-head hydropower plant equipped with Francis turbine

Refurbishment and upgrading of ageing hydropower plants contribute to increase of renewable energy share in modern electrical grid systems. The potential increase of discharge and flexibility of load variation may result in much higher dynamic loads on both refurbished and non-refurbished plant components during transient operating events. First, water hammer control strategies are outlined including operational scenarios, surge control devices, redesign of the pipeline components, or limitation of operating conditions. Water hammer models and solutions are briefly discussed in the light of their capability, availability and uncertainty. The core of the paper is devoted to investigations of water hammer effects in a high-head hydropower plant Piva, Montenegro which is currently in the final phase of refurbishment. The flow-passage system of the Piva HPP is comprised of the intake structure, followed by three parallel penstocks each with Francis type water turbine at the downstream end. The outlet part starts with three parallel draft tubes that are connected to a common lower orifice-type surge tank followed by tailrace tunnel and outlet structure. Computed and measured results for a selected emergency shut-down (ESD) of one turbine form full-load are compared and discussed. Then the validated computational model is used for simulation of ESDs for a wide operating range.

About Inverse Laplace Transform of a Dynamic Viscosity Function.

A dynamic viscosity function plays an important role in water hammer modeling. It is responsible for dispersion and decay of pressure and velocity histories. In this paper, a novel method for inverse Laplace transform of this complicated function being the square root of the ratio of Bessel functions of zero and second order is presented. The obtained time domain solutions are dependent on infinite exponential series and Calogero–Ahmed summation formulas. Both of these functions are based on zeros of Bessel functions. An analytical inverse will help in the near future to derive a complete analytical solution of this unsolved mathematical problem concerning the water hammer phenomenon. One can next present a simplified approximate form of this solution. It will allow us to correctly simulate water hammer events in large ranges of water hammer number, e.g., in oil–hydraulic systems. A complete analytical solution is essential to prevent pipeline failures while still designing the pipe network, as well as to monitor sensitive sections of hydraulic systems on a continuous basis (e.g., against possible overpressures, cavitation, and leaks that may occur). The presented solution has a high mathematical value because the inverse Laplace transforms of square roots from the ratios of other Bessel functions can be found in a similar way.

Numerical investigation of water hammer effect in pipeline of NPP considering two-phase compressible flow

In this paper, the water hammer effect of nuclear power plant (NPP) pipeline caused by pump switch and valve closure was investigated using numerical simulation. A piecewise formula was defined to approximately describing the process of pump opening. Different from the existing research, this paper emphatically focuses on the influence of the air cavity at the margin of pipeline on the pressure fluctuation. To observe the interaction of water and air phases, the volume of fluid (VoF) method was utilized here. The results conveyed that the amplitude and frequency of pressure are significantly dominated by the air cavity volume. A smaller air cavity volume corresponds to a lower maximum pressure, which is beneficial to the security of the pipeline. And with the reduction of air cavity volume, the pressure wave dissipates faster. This study suggests that the effective exhaust should be executed in advance before the operation of pump and valve.

Development of POLON—A Green Microsatellite Propulsion Module Utilizing 98% Hydrogen Peroxide

The following paper presents the key design and test activities associated with the development of POLON—a green microsatellite propulsion module using 98% Hydrogen Peroxide (HTP). POLON, which stands for “Polish Propulsion Module”, is the first step toward the development of a full, ready-to-be-commercialized satellite propulsion system at the Łukasiewicz—Institute of Aviation (Ł-IoA). The development of an entire microsatellite propulsion system within the frame of the POLON project effort is the natural milestone on the Ł-IoA green propulsion roadmap, which so far embodied research on fundamental HTP chemistry, work on elementary propulsion technologies, as well as the development of individual propulsion components. Within this article, POLON propulsion development logic is introduced first, and the major challenges associated with utilizing HTP for an orbital propulsion system are described. Consequently, the specific R&amp;D activities aimed at mitigating the identified issues and risks are discussed. Those cover analytical as well as experimental work, including, but not limited to, HTP compatibility studies with candidate construction materials, waterhammer effect studies, HTP catalyst testing and evaluation, and propellant tank manufacturing studies. The initial results for those activities are presented and, finally, further development plans are discussed.

New Integrated Energy Solution Idealization: Hybrid for Renewable Energy Network (Hy4REN)

A review of different energy components is detailed, as a baseline of fundamentals for the new integrated energy concept idealization. This innovative solution is a Hybrid for Renewable Energy Network (Hy4REN) based on well-studied elements to produce the best final solution. This proposal has the objective of improving energy system sustainability, facing fossil fuel and climate change restrictions, and increasing energy network flexibility. The most mature energy storage technology, pumped hydropower energy storage (PHES), is used to support both the grid connection and stand-alone modes, as an integrated hybrid energy system. The hybrid system idealization is modular and scalable, with a complementary nature among several renewables, using sea water in offshore mode to build an integrated solution. By evaluating a variety of energy sources, complemented with economic analysis, the benefits associated are evidenced using this sustainable methodology based only on renewable sources. Combined production of hydropower, using sea water, with pumped storage and water hammer events to create potential energy to supply hydropower in a water loop cycle, without consuming electrical energy, is explored. Other renewable sources are also integrated, such as floating solar PV energy and an oscillating water column (OWC) with coupled air-venting Wells and wind turbines, all integrated into the Hy4REN device. This complementarity of available sources allows us to improve energy storage flexibility and addresses the energy transition toward net-zero carbon emissions, inducing significant improvements in the sustainability of the energy network as a whole.

Instantaneous acceleration-based modeling of pumping systems response under transient events

Water hammer can cause pipeline eruptions after uncontrolled pump trip. In order to protect the pipeline from water hammer effects and monitor the transient flow, it is imperative to accurately predict pressure oscillation and surge energy dissipation for longer simulation periods. This study investigates the effectiveness of the water hammer control strategy by adjusting the rotational inertia of a pumping system alongside valve closing operations. In addition, it also explores the complex nature of the transient energy dissipation by using the one-dimensional instantaneous acceleration-based (IAB) unsteady friction models. To this end, the IAB unsteady friction (UF) models were improved to calculate the water hammer pressure by investigating the elastic pipe's response under transient events that are caused by pump trip and valve closure. Various boundary equations were derived and combined with water hammer governing equations to form the final system of equations to predict the transient pressure variation with time. After that, the numerical results of two IAB friction models (i.e., one and two-decay coefficient models, respectively) were compared with previous experimental data to verify the proposed transient solver. This solver was based on Method of Characteristics (MOC) and UF models. The results indicate that one-coefficient and two-coefficients UF models yield almost similar results that match with the experimental outcomes; however, the latter model is comparatively more complex in terms of formulation. Furthermore, a parametric study shows that increasing the moment of inertia of the pump and integrating it with the optimal operation of the valve helps in significantly controlling the transient pressure. This helps in reducing the check-valve slam and controls the water hammer with no need for additional protection devices. Results of the integral energy equation describe that the role of UF on the total dissipation of transient energy diminishes with an increase in the valve's closing time and inertia of the pumping system. Finally, the IAB-UF model acts as a valuable numerical tool that provides comprehensive information about the physical parameters required to protect high-head water supply systems from transient incidents.

RELAP5 application for water hammer analysis in different thermal-hydraulic systems

• Causes of water hammers: rapid valve operation, void-induced, condensation-induced. • RELAP5 code may represent water hammer due to valve operation and appearance of void. • The developed modelling recommendations are based on comparative analysis. • Water hammer in nuclear, fusion and district heating systems possible due to fast valve actions. • Integrity of pipelines in nuclear, fusion and district heating systems remain not violated. The water hammer phenomenon investigations employing RELAP5 code with one-dimensional two-fluid six-equation models of water and steam flow were performed and the main results shared in this paper. The capability of RELAP5 code to simulate transients leading strong pressure pulses was investigated employing the measurement results of three test facilities for different water hammer types: PPP at UMSICHT, CWHTF at FZR Dresden and PMK-2 at AEKI. Based on the benchmarking results the recommendations for the modelling of piping systems, which could be affected by different types of water hammer were developed and tested. The recommendations cover selection of thermal-hydraulic system conditions, parameters of modelling and RELAP5 code correlations. These recommendations have enabled to develop a detail RELAP5 models for the simulation of water hammer effects in further research works. The applications of RELAP5 code for water hammer analysis in different thermal-hydraulic systems (RBMK-1500 reactor main circulation loop, targets cooling/heating circuit in Wendelstein 7-X experimental stellarator facility and pipelines in district heating system) are presented in this paper. The performed analyses of transients demonstrated that the pressure pulsations could appear in all these systems as results of check valve closures. However, pressure surges are not so strong due to specific of such systems and integrity of pipelines remains not violated.