Results Of Hydraulic Analysis Research Articles

Avoiding Flood by Improving Cross-Sectional Capacity through River Normalization

Bekasi is one of the regions in Indonesia that often suffer from flooding. To overcome flooding problems in the Bekasi area, the Ciliwung Cisadane River Basin Center has begun a normalization project along the Bekasi River. This research aimed to evaluate the Bekasi River's cross-sectional capacity both before and after normalization. The analysis focused on the section where the Cileungsi and Cikeas rivers converge to the Bekasi weir. In this research, secondary data were employed, such as national digital elevation model data, detailed engineering designs of Bekasi River flood control activities, and rainfall data from the Cibinong Station that covers the period from 2006 to 2020. The result from planned flood discharge with the Nakayasu synthetic unit hydrograph method for a return period of 25 years on the Bekasi River was obtained at 665.81 m3/s. The results of hydraulic analysis before normalization with the HEC-RAS application show that flooding occurred at 102 out of 116 stations, with capacities of river cross-sections ranging from 453.49 m³/s to 665.71 m³/s at these overflow stations. Following the river normalization process, the cross-sectional capacity at all Bekasi River stations can accommodate flood discharge without any instances of overflow.Keywords: Flood, HEC-RAS, Nakayasu, Normalization, Rainfall.

ANALISA KAPASITAS KANAL PASSO KOTA AMBON MENGGUNAKAN HEC-RAS 5.03

Passo Village is a lowland area, where the Passo area has quite dense residential areas. . The increase in population growth and changes in land use that occur in the Passo Village area have resulted in many changes that will have negative impacts in the form of flooding or inundation. This is what happens in the Passo Village area, where during the high intensity rainy season there are often floods or puddles around the area. The existing canal system is not functioning properly. This is due to the narrowing of the Passo Canal channel due to the presence of buildings on the canal border such as residences and shops. The Passo Canal was used as a rubbish dump. The dimensions of the canal have changed and cannot accommodate the existing hydrological discharge. In overcoming this problem, the aim of this research is to determine the water level in the Passo Canal with the help of HEC-RAS 5.03 Software and to find out preventive methods for overcoming flooding problems in the Passo Canal. The initial stage is hydrological and hydraulic analysis. The results of the hydrological analysis are rainfall distribution using the Log Pearson III distribution, to calculate the planned discharge using the Der Weduwen method, it is obtained with a 10 year return period of 0.398 m3/sec. The results of hydraulic analysis using HEC-RAS 5.03 software showed that the highest water level at the S15 canal section was 0.52 meter. From this research it can be concluded that the Passo Canal requires flood management efforts, especially by normalizing the canal cross-section.

Evaluation of Krueng Tripa River Capacity in Ujung Krueng Village, Nagan Raya Regency, Indonesia

Flood events are very common in the lowlands as often happens in Ujong Krueng Village, Tripa Makmur District. This study aims to determine the magnitude of the design flood discharge using the Nakayasu method and evaluating the cross-sectional capacity of the Krueng Tripa River in Ujong Krueng Village. The data used are both primary and secondary. Primary data consists of measurements of river slope, river flow velocity, river depth and river width, while secondary data consists of rainfall data, Krueng Tripa watershed maps and Krueng Tripa River situation maps. The results of the design flood discharge calculation using the Nakayasu method show that the 2-year return period (RP) is 3237.46 m3/s, the 5-year RP is 4389.53 m3/s, the 10-year RP is 5177.08 m3/s, the 10-year RP is 5177.08 m3/s, the 25-year RP is 6199.32 m3/s, the 50-year RP is 6979.04 m/s, and the 100-years RP is 7778.23 m3/s. From the results of hydraulic analysis on the section of the Krueng Tripa river in Ujong Krueng Village using the HEC-RAS 6.1.0 software, it shows that in the 2-year return period, on pias 1, 7 and 8 experienced overflows on both sides while on pias 2, 3, 4, 5 and 6 only overflow on the right side. In the return periods of 5th, 10th, 25th, 50th - year and 100th, all the streams had overflowed, the highest overflow reached 4.84 m, while the lowest overflow reached 0.30 m.

Identification of Flood-prone Areas using HEC-HMS and HEC-RAS, the Case of Ciberang River Basin, Lebak District of Banten Province

It is common practice that flood hydrograph simulations help to provide better flood prediction and flood damage reduction planning. These efforts require information on flood-prone areas identification from the hydrological and hydraulic analysis results. Historically, the Ciberang River Basin has experienced floods. Those floods cause the loss of human life and damage some houses along the river’s channels, especially in Lebak District, Banten Province, Indonesia. The main objective of this study is to identify flood-prone areas based on the simulation result of a hydrologic and hydraulic model of catchment response due to several extreme rainfall events using HEC-HMS and HEC-RAS software. Rainfall and discharge data measured at the Ciberang-Sabagi water level gauge on 10 January 2013 were used to calibrate hydrological watershed parameters. The hydraulics channel routing is started from the planned location of the Sabo dam to the downstream control point. The next stage was the simulation of rainfall-runoff transformation and 1D unsteady flow channel routing for the 2, 5, and 10-years floods return periods. The main result of this study is a flood hazards map that shows the spatial distribution of the area and inundation depth for each return period of the flood.

Parametric study of the hydraulic performance of counter flow LN2 cooled cold dielectric HTS cable

A hydraulic analysis is promising to perceive the complex turbulent flow behavior of sub-cooled liquid nitrogen (LN2) through counter flow cold dielectric high temperature superconducting (HTS) cables. Such counter flow HTS cables comprise of an annular (cryostat) and a central corrugated pipe separated by a HTS conductor layer. Flow of sub-cooled liquid nitrogen through central and annular corrugated pipe affects the hydraulic performance of HTS cable due to the sudden expansion and contraction in the corrugated pipes shape. Therefore, in the present work, the hydraulic performance in terms of friction factor, pressure drop, pumping power and flow pattern of LN2 through central (forward flow) and annular (return flow) corrugated pipe (cryostat) are investigated computationally. Moreover, the effect of various parameters (corrugation pitch and depth) on hydraulic performance is also examined. In order to analyze the effect of corrugation pitches (6, 8, 10 and 12mm) and depths (4, 6 and 8mm), ten different two dimensional (2-D) axisymmetric model of counter cooled HTS cable are developed and solved using computational fluid dynamics (CFD). Additionally, two-equation turbulence model (k-ϵ) is being used to accurately predict the complex flow pattern of LN2 in corrugated pipes. Furthermore, the results of pressure drop are validated with available experimental results. Hence, the hydraulic analysis results are beneficial in opting the corrugated pipes configuration and the allied cryo-units for fluid pumping.

Development of Preliminary Seismic Performance Evaluation Method for Water Supply Pipes considering Hydraulic Characteristics

The seismic performance evaluation of water supply systems is generally conducted in two stages: a preliminary and a detailed evaluation process. In the case of water pipelines, the priority pipes are selected through preliminary evaluation for a detailed evaluation. However, as the preliminary seismic performance evaluation method for existing water pipes solely focuses on their installation year and structural evaluation, it does not reflect the hydraulic characteristics of the water supply, which is the main purpose of water pipes. Therefore, this study proposed an evaluation method for the existing preliminary evaluation judgment index, by considering the calculation method for the probability of spatial failure, as well as the index obtained through hydraulic analysis results. The proposed methodology was applied to a domestic regional water supply system to be verified, and the results were analyzed. The proposed method is expected to serve as a result of basic research to enhance the seismic performance evaluation method in the future.

Thermo-mechanical assessment of the optimized CFETR water cooled ceramic breeder blanket

The Water Cooled Ceramic Breeder (WCCB) blanket is one of the candidates for Chinese Fusion Engineering Test Reactor (CFETR). Within the framework of the engineering design of CFETR, an updated design of WCCB blanket was proposed corresponding to the latest core parameters (major radius=7.2 m, minus radius=2.2 m). Thermal-hydraulic analyses preliminarily showed the feasibility of the previous blanket design. However, the flow distribution of the blanket was unsatisfactory. Thus, optimization of cooling systems of the blanket was performed accordingly. The optimized blanket design as well as the hydraulic analysis results are presented. Then, in order to investigate the thermal-hydraulic and thermo-mechanical behaviors of the optimized WCCB blanket under normal and accidental operation scenarios, thermo-mechanical analyses were performed following a computational approach based on the Finite Element Method (FEM), using the ANSYS commercial FEM code. The obtained results were assessed in order to verify the compliance with the blanket design criteria ITER SDC-IC code. Structural feasibility of the optimized blanket design was verified.

Conceptual design and analysis of a megawatt power level heat pipe cooled space reactor power system

A new conceptual design of a megawatt power level heat pipe cooled space reactor (HPCR) power system adopted the integrated heatpipe-fuel modules is developed. A moderated thermal-neutron spectrum reactor, is designed with the thermal power of 3.2 MW. It consists of 234 HP-Fuel elements, which is a central lithium heat pipe surrounded by highly enriched UN fuel pellet with cladding on both radial sides. The dual closed Brayton dynamic conversion using binary He-Xe gas as working fluid is adopted. System waste heat is transported by the sodium–potassium (NaK) alloy cooling circuit to the potassium heat pipe radiation panels. The neutronic and CFD thermal–hydraulic analysis results are provided for the current design. The normal operation condition and event of a heat pipe failure are calculated and assessed. The redundancy and reliability of the core design is evaluated. The main design parameters of the dual-Brayton energy conversion system and heat pipe radiation panel are also illustrated. System heat balance analysis is performed. The potassium heat pipe radiator is designed and evaluated for the thermal performance.

An Application of the A-PDA Model For the Interconnected Operation Among Adjacent Blocks of Water Distribution Systems In Case of Emergency

The water distribution system is an important social infrastructure providing customers with stable and safe water supply. The fact, however, is that it is not free from various abnormal situations arising from internal / external factors. In case of a water supply failure due to abnormal situations, the emergency interconnected operation between adjacent blocks in the system is one of the most effective countermeasures. To simulate these types of emergency operations, existing hydraulic analysis models, which are based on the infinite water supply assumption, may simulate unrealistic results such as satisfying sufficient water supply for more demand nodes than actual ones. If they want to have more realistic hydraulic simulation result for these situations, it is required to adopt a new hydraulic analysis which is able to consider insufficient water supply for all demand nodes. Demand Driven Analysis (DDA) and Pressure Driven Analysis (PDA) are most commonly used hydraulic analysis. DDA performs a hydraulic analysis based on the assumption that the demand at demand nodes is always 100% satisfied which derives unrealistic results in abnormal situations. In the case of the PDA, it considers the relationship between hydraulic pressure and available flow rate, which is more reliable than the DDA for abnormal operating conditions. However, since DDA and PDA are basis on the infinite water supply assumption, unrealistic hydraulic analysis results may be obtained when they are applied to the insufficient water supply condition such as the emergency interconnected operation between adjacent blocks due to one or more reservoirs may not be working properly. Therefore, Lee et al. (2018) has proposed the Advanced-Pressure Driven Analysis (A-PDA) applying the concept of limited source to the existing PDA. In this study, we apply the PDA and the A-PDA to simulate the hydraulic condition of the emergency interconnected operation between adjacent blocks for a water supply network in Korea and compare the results from them. The target network supplies water to 84,000 households and it consists of 3 reservoirs, 1,492 nodes, 1,937 pipelines, 8 pumps and 10 interconnected emergency pipes. Each reservoir takes responsible for its individual block. When one of the reservoirs cannot supply water to its individual block, the block will be supplied water through the emergency pipes from the adjacent reservoir. Fig 1 shows the layout of target network and Table 1 shows the properties of each reservoir. To explore the effect of the limited water supply condition, we generate an operation scenario: RES1 stops water supply at 00:00hr (mid night) and RES2 and RES3 supply water to Block1 for the emergency. Then, the PDA and the A-PDA are used to simulate this emergency operating condition. The initial water depth of RES2 and RES3 is 3m and 2.7m, respectively. Fig. 2 shows the available supply ratio (ASR, = available demand/required demand) with time by the PDA and the A-PDA for Block1. The ASR with time by the PDA for Block1 show us that emergency water supply to Block1 from RES2 and RES3 can be maintained through the simulation period even though the ASR are 20% to 40%. On the other hand, The ASR with time by the A-PDA for Block1 show us that the emergency water supply to Block1 ceases after 16:00hr. The reason we obtain two different water supply results for Block1 is due to the assumption of the PDA which is that the amount of water supply is unlimited during the simulation period. In the PDA, the water depth of a reservoir is always maintained at the initial set value so that the amount of water demand at demand nodes should be provided. However, for the emergency operating condition we generate for this study, the amount of water from RES2 and RES3 is insufficient to supply water for the entire network without RES1. As shown in Fig. 3, the water depths of RES2 and RES3 are continuously decreased and RES2 is empty at 16:00hr and RES3 is depleted after 39:00hr. After 16:00hr, RES3 is the only water source for the entire network and Block1 cannot be supplied water from RES3 sufficiently. From this simulation results, the A-PDA simulates this type of the water supply situation more realistic than the PDA does since without RES1, obviously, the entire network cannot be provided with sufficient water from RES2 and RES3. Therefore, in the case of the hydraulic analysis which needs to consider water supply quantity such as the interconnection operation required, the application of the A-PDA model is indispensable. Additionally, the application of the A-PDA can anticipate the possible water supply time and the possible emergency interconnected operating time in the abnormal operating condition, which is impossible to obtain by the existing hydraulic analysis. These two values will be used to design or to establish the emergency operating plan for a water supply network for better service quality.

Status of Indian LLCB TBM program and R&D activities

The Indian LLCB TBM, currently under development, will be tested from the first phase of ITER operation (H–H phase) in one-half of the ITER port no-2. The present LLCB TBM design has been optimized based on the neutronic as well as thermal hydraulic analysis results. LLCB TBM R&D activities are primarily focused on (i) development of technologies related to various process systems such as Helium, Pb–Li liquid metal and tritium, (ii) development and qualification of blanket materials viz., structural material (IN-RAFMS), tritium breeding materials (Pb–Li, and Li2TiO3), (iii) development and qualification of fabrication technologies for TBM system. The present status of LLCB TBM design activities as well as the progress made in major R&D areas is presented in this paper.

Accuracy quantification metrics for CFD simulation of in-vessel flows

Within more general frameworks dealing with uncertainty evaluation and code assessment, well assessed methodologies exist for the accuracy evaluation of system thermal hydraulic analysis results. As long as multi-dimensional transient data is involved, such as space and time distributions obtained from CFD calculations and experiments, the task of quantifying the accuracy and defining acceptance criteria becomes harder, and there seems to be a lack of systematic approaches available to that purpose.An example of such multi-dimensional data is represented by the time and space distribution of coolant properties (e.g. temperature, boron concentration) at the reactor core inlet, which is relevant to reactor safety as local perturbations potentially induce power excursions. An attempt is made here to tackle the accuracy quantification issue for that class of data, in a somewhat empirical way, i.e. by proposing a set of parameters that can be used, after proper qualitative analysis of measured data and code simulation results, to characterize the target variable time and space distributions, and to quantify the deviation of the simulation from the experimental data. The advantage of using such kind of metrics based on many parameters relies in the ability to cover different relevant features of the target variables and thus provide a more complete assessment and allow statements about the overall agreement.

Zeuch method-based injection rate analysis of a common-rail system operated with advanced injection strategies

In the present paper the results of an experimental hydraulic analysis of a common rail injection system are discussed. A complete wet system, composed of an automotive injection pump, a rail and a Bosch CRI2.16 injector, is analyzed in realistic operating conditions. The hydraulic analysis is carried out by a Zeuch method-based instrument which is used to measure the injected volume and the injection rate; both these quantities are obtained in mean terms and shot-to-shot resolved in order to investigate the system operation dispersion. The injection rate measurement is supplemented by both the rail pressure and the needle movement measurements to better analyze the injector behavior. Some different advanced injector driving strategies are analyzed, focusing on reduced dwell time operation conditions.Peculiar attention is devoted to the injection process start detection, which is of special interest in case of multiple injections. An accurate analysis of the injection rate time-history suggests that in the initial part of the process the flow is directed toward the injector nozzle (negative flow) and only after a short time the injection rate profile becomes positive, apparently indicating the start of the injection process. In order to define a proper start time detection criterion, the results of the hydraulic analysis were compared with the spray evolution analysis based on imaging carried out by an ensemble-averaged approach. This comparison suggested that the injection start can be derived by the hydraulic analysis: the outflow onset is generally synchronized with the first positive values of the injected volume, computed as the time integral of the injection rate profile.

Thermal hydraulic and safety analysis for core conversion (HEU–LEU) of Syrian Miniature Neutron Source Reactor

The paper presents the behavior and properties analysis of the low enriched uranium fuel compared with the original high enriched uranium fuel. The MNSR reactor core was modeled with both fuel materials and the reactor behavior was studied during the steady state and abnormal conditions. The MERSAT code was used in the analysis. The steady state thermal hydraulic analysis results were compared with that obtained from the experimental results hold during commissioning the Syrian MNSR. Comparison with experimental data shows that the steady-state behavior of the HEU core was accurately predicted by the MERSAT code calculations. The validated model was then used to analyze LEU cores with two proposed UO2 fuel pin designs. With each LEU core, the steady state and 3.77 mk rod withdrawal transient were run and the results were compared with the available published data in the literatures for the low enriched uranium fuel core. The results reveal that the low enriched uranium fuel showed a good behavior and the peak clad temperatures remain well below the clad melting temperature during reactivity insertion accident.

Water distribution system model calibration under uncertainty environments

The calibration process of water distribution system models allows for accurate and reliable hydraulic analysis results. Thus, calibration is of utmost importance if adequate operation and maintenance model-based procedures are sought. However, in emerging economies, there is a series of factors that make it more difficult to construct accurate models, including very poor information management, unusually high leakages and the presence of a large number of illegal connections. While some of the model variables are assumed to be known under normal circumstances, these factors make it necessary to consider them for calibration as well. This paper presents a calibration methodology flexible enough to address such problems allowing the calibration of pipe diameter, roughness and minor losses, and nodal demands and leakages. A genetic algorithm was implemented as well as a constraint programming algorithm that makes direct use of hydraulic criteria to advance in the solution space. The methodology was tested on a real system in Colombia with a satisfactory outcome. The use of these techniques results in major reduction of calculation time and similar or superior results in comparison to manual methods.

水理解析を目的とした流域ＧＩＳデータのオブジェクト構造化と応用

Considering the concept of object-oriented GIS, the mutual relationship of GIS data for hydraulic analysis was considered, and GIS data of drainage basin was constituted for object-oriented structure model. To facilitate the processing and representation of GIS object data, a GIS software program with the customized functions was developed. Customized functions were 1) auxiliary editing, 2) automated functions for elucidating relationships between objects and others, and 3) automatic generation and display functions for the results of hydraulic analysis. The program was applied to the hydraulic analysis in a river basin with 191 reservoirs and 211 channels, and hydraulic analysis data in this basin was automatically generated. As a result, large labor saving was enabled. The program was also applied to a multiphase functional evaluation of an agricultural waterway, and was proved useful for assessing the continuity of a fish habitation network divided by weirs or pumps.

Treatment of the thermal–hydraulic uncertainties in the pressurized thermal shock analysis

The pressurized thermal shock (PTS) analysis is a quantitative analysis to calculate the vessel failure probability of the embrittled reactor pressure vessel. The PTS analysis consists of three major parts, such as the probabilistic safety analysis (PSA), the thermal–hydraulic analysis (T/H), and the probabilistic fracture mechanics (PFM) analysis. Because each analysis involves many parameters and assumptions associated with the uncertainties, it is important to identify and incorporate them into the analysis. Though the PSA and PFM analysis can be easily treated statistically, the thermal–hydraulic analysis results are very difficult to be treated statistically. Instead, sensitivity analyses of the thermal–hydraulic inputs were performed to understand the significance of the variation in the thermal–hydraulic inputs to the PFM analysis. In this study, the existing PFM code was modified to incorporate the uncertainties in the thermal–hydraulic inputs for the PFM analysis. The effects of the uncertainties in the thermal–hydraulic inputs for the vessel failure probabilities were evaluated using the modified code. The results showed the effects of uncertainties in the thermal–hydraulic inputs on the vessel failure probabilities are not significant for the ranges of the transient types. Even for the larger uncertainties, the effects on the vessel failure probabilities are small. Also, the effects of the thermal–hydraulic uncertainties vary depending on the transient characteristics such that the effects are greatest for the pressure dominant transient. Within the transient, the relative increases in the failure probabilities are greatest for the circumferentially oriented semi-elliptical flaws. It was found that the results of the sensitivity analysis using one standard deviation are conservative enough to bound the analysis results considering the uncertainties in the thermal–hydraulic inputs.

Fuel behavior comparison for a research reactor

The paper presents the behavior and properties analysis of the low enriched uranium fuel, which will be loaded in the Romanian TRIGA 14MW steady state research reactor compared with the original high enriched uranium fuel. The high and low enriched uranium fuels have similar thermal properties, but different nuclear properties. The research reactor core was modeled with both fuel materials and the reactor behavior was studied during a reactivity insertion accident. The thermal hydraulic analysis results are compared with that obtained from the safety analysis report for high enriched uranium fuel core. The low enriched uranium fuel shows a good behavior during reactivity insertion accident and a revised safety analysis report will be made for the low enriched uranium fuel core.

Thermal–hydraulic feasibility analysis on uprating the HTR–PM

In order to meet energy demand in China, the high temperature gas-cooled reactor–pebble-bed module (HTR–PM) is being developed. It adopts a two-zone core, in which graphite balls are loaded in the central zone and the outer part is fuel ball zone, and couple with a steam cycle. Outer diameter of the reactor core is 4.0 m and height of the core is 9.43 m. The helium inlet and outlet temperature are 250 and 750 °C, respectively. The reactor thermal power is 380 MW. Preliminary studies show that the HTR–PM is feasible technologically and economically. In order to increase the reactor thermal power of the HTR–PM, some efforts have been made. These include increasing the height of reactor core, optimizing the thickness of fuel zone and better selection of the scheme of central graphite zone, etc. Basic design concepts and thermal–hydraulic parameters of the HTR–PM are given. Measures to increase the thermal power are introduced. Thermal–hydraulic analysis results are presented. The results show that, from the viewpoint of thermal–hydraulics, it is possible to increase the reactor power.