Optimal Flow Path Research Articles

Optimization of Cavitation Performance of High-Speed Centrifugal Pump Based on the Meta-Model of optimal Prognosis

Abstract Using a specific type of high-speed centrifugal pump as an example, this study conducted a parameterized optimization design on geometric parameters of the impeller’s flow path. A response sample space was generated with the flow path geometric parameters as input and pressure increment and cavitation volume as output. Based on the Meta-Model of optimal Prognosis, the optimal surrogate model was fitted, and a global sensitivity analysis was conducted. The results indicated that the impeller’s inlet edge parameter and mid-curve parameter had a significant impact on the pressure increment and cavitation volume of the pump. Using a genetic algorithm, the optimal flow path geometric parameters were obtained, and numerical simulation methods were applied to verify the obtained parameters. The results showed that after optimization, the pressure coefficient of the centrifugal pump increased by 0.035, and the cavitation performance improved by 22.28%. The impeller cavitation area and void volume were significantly reduced, and the flow path pressure distribution and flow state were improved.

Pseudo-transient flow path optimization of a solar tower receiver operating with supercritical carbon dioxide

Aiming to further promote the decarbonization of energy production processes, this article simulates and optimizes the pseudo-transient behavior of a cylindrical solar receiver subjected to a spatially varying concentrated heat flux. The model employed, which accounts for its thermal–hydraulic behavior, uses supercritical carbon dioxide (s-CO2) as the heat transfer fluid and is based on a literature-validated hybrid formulation that axially discretizes the tube of the receiver and simultaneously solves the 2-D temperature distribution within the cross-section of each node. The operational conditions imposed on the receiver were determined such that it can produce 10 MW in a recompression Brayton cycle. Also, the receiver’s surface was exposed to a spatially variable concentrated solar boundary condition based on the direct normal irradiance (DNI) of a representative day for each month of the year, which was selected from the typical meteorological year (TMY) in Seville (Spain). The results showed that the combined thermal–hydraulic efficiency of the receiver increases with the number of panels and that the mass flow flowing through each symmetrical side of the receiver should not necessarily be identical for achieving maximal efficiency. More importantly, the results showed that by simply changing the location of the s-CO2 inlet and outlet ports, one can increase the efficiency of the receiver by about 3 % while considering the exact same concentrated solar irradiation.

Thermal management of fuel heat sink in aircraft via flow path optimization

With the rapid increase of aircraft thermal loads, efficiently utilizing the fuel heat sink has received widespread attention in recent years. To improve the performance of the aircraft fuel thermal management system (AFTMS), a concept of the fuel heat sink consumption rate (FHSCR) is proposed to assess the system heat dissipation, and an optimization criterion of fuel heat sink is established based on the FHSCR. Besides, a new architecture of the AFTMS with a middle fuel return branch (MFRB) and a recirculation fuel supply branch (RFSB) is designed to enhance the heat dissipation capacity, and unlike previous studies, only the flow path of the fuel supply and return subsystem (FSRS) has been changed here without additional fuel tanks. Moreover, a dynamic optimal controller based on the particle swarm optimization (PSO) algorithm with the minimum variation distance (MVD-PSO) is developed for obtaining the optimal control parameters and eliminating the parameter oscillation, which is applied in the comparison calculations under both a single condition and a complete mission profile. The calculation results show that compared to the original architecture, the new architecture can reduce the FHSCR by 14.16% under the standard condition, and the thermal endurance of the standard and extreme conditions is extended by 37.42% and 19.54%, respectively. In addition, the new architecture exhibits a better thermal management performance during the whole mission as well. To sum up, comprehensively dealing with the waste heat by both the combustion fuel and ram air is crucial for system cooling, and the new architecture improves the heat dissipation capacity of the AFTMS significantly. This paper provides a novel flow path optimization guide for the AFTMS.

Influence of the centrifugal pump impeller vanes parameters on its energy performance at operating with high-viscosity liquid

BACKGROUND: The currently existing methods for recalculating the operation of centrifugal pumps for viscous fluids cover a sufficiently small range of viscosities. In addition, the considered papers cover the recalculation only, not the search for the optimal geometry of the centrifugal pump for high-viscosity liquids. In this paper, computational fluid dynamics tools were used to test the ability of centrifugal impellers to pump liquids with a viscosity of up to 20,000 sSt, as well as to search for the optimal geometry of the flow path.
 AIM: Determination the dependence pattern of the geometric parameters, including vanes, of the optimal geometry of the centrifugal pump flow path at various values of flow rate and viscosity.
 METHODS: A numerical modeling method based on the solving of discrete analogs of the basic equations of hydrodynamics is used in this paper.
 RESULTS: It was proved that, with the considered viscosities, an impeller with a profiled vane, but with a smaller wrap angle and height, is capable of more efficient operation than a disk impeller. The dependences of the parameters of the optimal flow paths on the characteristics for which their optimization was carried out are given.
 CONCLUSION: Based on the study results, it can be stated that it is advisable to use centrifugal impellers in case of high viscosity of the liquid, taking into account the choice of non-classical values of the geometric parameters of the flow path, including the height and angle of its vanes.

Multi-objective reduced-order design optimization of single-phase liquid coolers for electronics

Thermal management using liquid cooled cold plates is a key enabler in modern electronic systems such as power converters and multi-chip arrays. Traditional cold plate designs are limited in their ability to handle the heterogeneous heat profiles in ever-larger modern multi-chip arrays requiring design optimization. This work demonstrates a design optimization method for liquid-cooled cold plates subjected to discrete heat dissipation profiles. We used reduced order performance modeling enabled by splitting the heat sink geometry onto a coarse grid with up to 50 elements each assigned with a simplified flow block such as a straight, elbow, or tee section. Correlations for thermal-fluidic performance metrics were used to obtain the pressure drop and surface temperature. Multi-objective design optimization focused on minimizing the pressure drop and temperature was broken down into layout and geometry optimization sub-steps. Layout optimization found the optimal flow path from inlet to outlet using a novel optimal path search method combining pathfinding algorithms with search on a random population. Geometry optimization solved for the dimensions of the coarse grid elements and the corresponding flow blocks using gradient based optimizers. We experimentally tested an aluminum water-cooled heat sink design generated by the reduced order optimization demonstrating a thermal resistance of 0.065 K/W. We compared the performance of our optimal designs with conventional and topology optimized cold plate designs to benchmark performance, computational cost, and computational time. Topology optimized designs showed a 22% reduction in average heated surface temperature for similar pressure drops. However, the computation time required to generate the topology optimized design was more than one order of magnitude higher than the reduced order method, requiring over 3,600 s to generate the optimal design. Our reduced order optimization in comparison provides optimal designs at computational timescales of 60 s.

A model of temporal and spatial river network evolution with climatic inputs

Predicting the temporal and spatial evolution of the river network is part of the Earth's critical zone investigations, which has become an important endeavor. However, modeling integration of the river network and critical zone over millions of years is rare. We address the problem of how to predict integrated river length development as a function of time within a framework of addressing the critical zone depth as a function of time. In case of groundwater-river interaction, we find a non-linear spatio-temporal scaling relationship between time, t, and total river length L, given by t≈Lp with power p being near 1.2. The basis of our model is the presumption that groundwater flow paths are relevant to river integration. As river integration may proceed over disconnected basins with irregular relief, the relevant optimal subsurface flow paths are proposed to be defined within a 3D network, with optimal path exponent 1.43. Because the 2D model of the river length has already been shown to relate to a power of the Euclidean distance across a drainage basin with the predicted universal optimal path exponent from percolation theory, Dopt = 1.21, the optimal groundwater paths should relate to the surface river length with an exponent equaling the ratio 1.43/1.21 = 1.18. To define a predictive relationship for the river length, we need to use specific length and time scales. We assume that the fundamental specific length scale is a characteristic particle size (which is commonly used to define the pore scale flow network), and the fundamental time scale is the ratio of the particle size to the regional groundwater flow rate. In this paper, we consider cases of predicting spatio-temporal scaling of drainage organization in the southwestern USA–the Amargosa, Mojave, Gila (and its tributaries) and the Rio Grande, and Pecos Rivers. For the Mojave and Gila Rivers, theoretical results for time scales of river integration since ca. 10 Ma are quite predictive, though the predicted time scales exceed observation for the Rio Grande and Pecos.

A Boost-Type Three-Port Resonant Forward Converter With Flexible Power Flow Path Optimization for PV Systems

This brief proposes a three-port resonant forward topology for low power applications. Specifically, a modified boost converter, which adds a controllable freewheeling path, is combined with a resonant forward converter to simultaneously fulfill PV voltage regulation and battery charging management. Then, by taking the benefit of more flexible power flow adjustment, the PV and the battery can adaptively share the load current with reduced power conversion stages. Therefore, in comparison to other LLC-type three-port converters, the proposed scheme achieves the better compromise between cost and power efficiency.

Effects of passive-storage conceptualization on modeling hydrological function and isotope dynamics in the flow system of a cockpit karst landscape

Abstract. Conceptualizing passive storage in coupled flow–isotope models can improve the simulation of mixing and attenuation effects on tracer transport in many natural systems, such as catchments or rivers. However, the effectiveness of incorporating different conceptualizations of passive storage in models of complex karst flow systems remains poorly understood. In this study, we developed a coupled flow–isotope model that conceptualizes both “fast-flow” and “slow-flow” processes in heterogeneous aquifers as well as hydrological connections between steep hillslopes and low-lying depression units in cockpit karst landscapes. The model tested contrasting configurations of passive storage in the fast- and slow-flow systems and was optimized using a multi-objective optimization algorithm based on detailed observational data of discharge and isotope dynamics in the Chenqi Catchment in southwestern China. Results show that one to three passive-storage zones distributed in hillslope fast-/slow-flow reservoirs and/or depression slow-flow reservoirs provided optimal model structures in the study catchment. This optimization can effectively improve the simulation accuracy for outlet discharge and isotope signatures. Additionally, the optimal tracer-aided model reflects dominant flow paths and connections of the hillslope and depression units, yielding reasonable source area apportionment for dominant hydrological components (e.g., more than ∼ 80 % of fast flow in the total discharge) and solute transport in the steep hillslope unit of karst flow systems. Our coupled flow–isotope model for karst systems provides a novel, flexible tool for more realistic catchment conceptualizations that can easily be transferred to other cockpit karst catchments.

EDCSuS: Sustainable Edge Data Centers as a Service in SDN-Enabled Vehicular Environment

Cloud computing has emerged as one of the popular technologies which provide on-demand services to the end users. Such services are hosted by massive geo-distributed data centers (DCs). Nowadays, connected vehicles in a smart city can also avail cloud services through Internet using cellular technologies. But, the advent of 5G technology has posed challenges for DCs such as-low latency and higher data rate requirements. To handle these challenges, edge-DCs (EDCs) can be deployed across a smart city to provide low latency services to the connected vehicles. In lieu of this, in this paper, EDCSuS: Sustainable EDC as a service framework in software defined vehicular environment is proposed. In EDCSuS, first, a software defined controller handles the incoming requests and suggest an optimal flow path. Second, a multi-leader multi-follower Stackelberg game is presented for resource allocation. Third, to improve the resource utilization, a cooperative resource sharing scheme is designed, thereby minimizing the energy consumption of servers in the EDCs. Lastly, a caching scheme is presented to avert excessive energy consumption for retracing the lost link due to vehicular mobility. The efficacy of the proposed scheme has been evaluated using extensive simulations with respect to various parameters. The results obtained prove the effectiveness of EDCSuS.

Level-set based topology optimization for a microfluidic static mixer with two flow modelings

Static mixers have been widely used in the biochemical industry because they are portable, reliable and low-energy. We construct a rection-diffusion equation-based (RDE) level-set method (LSM) to conduct topology optimization (TO) for a T-junction static mixer design. The RDE-based TO method combines the concept of the Ersatz material approach with the boundary variation level set-based method. In the context of a fluid-based TO problem, a fluid-solid system can be modeled by using either a monolithic formulation or a system of separate equations. In this paper, we present a comparative study and discuss their different features. After describing the numerical example model, we show the optimized flow path based on both flow modeling strategies. The generally optimized flow paths are quite similar, indicating the CPU time to calculate. Due to algorithmic differences, the use of a system of separate equations is more advantageous with respect to CPU time.

Specific Features of the Replacement of the Available Flow Path by the Optimal Flow Path when Upgrading the Steam Turbine High-Pressure Cylinder

This scientific paper gives the main research data obtained during the solution of the search problem to define optimal parameter values for the thermal circuit of the К-540-23.5 turbine unit that would provide the most efficient operation both for the optimal version of the high pressure cylinder (HPC) as part of the turbine unit and the turbine unit on the whole. The effect of the distribution of heat differences in the stages of the optimal flow part of the high pressure cylinder used by the К-540-23.5 turbine on the integral quality factors of the turbine unit has been assessed. The calculation studies of the thermal circuit of the turbine unit with the optimal flow section of the high-pressure cylinder showed that the temperature of the underheated feed water in the high pressure heater (HPH) arranged near the steam generator has the most critical effect on the power and economical efficiency of the high pressure cylinder and entire turbine unit. The two-criterion Pareto problem for the upgrading of the turbine unit was formulated and solved to define optimal underheating temperature values. Consideration was given to the two variants of the solution of the optimization problem for the feed water underheating temperature in the high pressure heater. Comparison and analysis of the two variants of solution for the two-criterion optimization problem showed the identity of the obtained data and it confirms the correctness of the problem formulation and the algorithms used for its solution.

A throughflow-based optimization method for multi-stage axial compressor

A multi-objective optimization tool for multi-stage axial compressors is developed based on an automatically calibrated throughflow method. The Euler-based throughflow equations with blade force terms are solved using a time-marching finite volume method to obtain the meridional flow fields, while the traditional empirical deviation and loss correlation are substituted by several Kriging metal models constructed based on the circumferentially averaged results of three-dimensional computational fluid dynamics simulations. Optimization maximizing both the total pressure ratio and adiabatic efficiency is performed to search for the optimal flowpath and radial distributions of geometrical parameters by using the non-dominated sorted genetic algorithm II method. A low-speed 4.5-stage axial compressor is chosen as the test case to verify the procedures, including throughflow solver validation, design optimization, etc. The throughflow solver has proved to be reliable. The optimization under the design operation condition achieves a great increase in the total pressure ratio and a small increase in adiabatic efficiency. Moreover, improvements in the total pressure ratio and stall margin are also observed for the optimal configuration in this optimization, with a decrease in the cost of adiabatic efficiency under the operation condition near stall.

Non-linear hydrologic organization

Abstract. We revisit three variants of the well-known Stommel diagrams that have been used to summarize knowledge of characteristic scales in time and space of some important hydrologic phenomena and modified these diagrams focusing on spatiotemporal scaling analyses of the underlying hydrologic processes. In the present paper we focus on soil formation, vegetation growth, and drainage network organization. We use existing scaling relationships for vegetation growth and soil formation, both of which refer to the same fundamental length and timescales defining flow rates at the pore scale but different powers of the power law relating time and space. The principle of a hierarchical organization of optimal subsurface flow paths could underlie both root lateral spread (RLS) of vegetation and drainage basin organization. To assess the applicability of scaling, and to extend the Stommel diagrams, data for soil depth, vegetation root lateral spread, and drainage basin length have been accessed. The new data considered here include timescales out to 150 Myr that correspond to depths of up to 240 m and horizontal length scales up to 6400 km and probe the limits of drainage basin development in time, depth, and horizontal extent.

Flow Path Optimization for Soft Pneumatic Actuators: Towards Optimal Performance and Portability

Soft pneumatic actuators (SPAs) are highly desirable for interactive robotics applications owing to their unconventional properties like high compliance, safe human-machine interaction and adaptable design space. The SPA dynamic behaviour is governed by pneumatic supply systems (PSSs) consisting of source, valve, tubing and fittings. Although their functionality is well known, the inter-dependence of PSS components and their impact on the SPA behaviour has not been quantified, especially in the context of performance and portability. Using the metrics of maximum actuation frequency, air and energy consumption per actuation cycle, here we systematically investigate the effect of five parameters: SPA size, tubing diameter and length, source pressure and valve flow capacity. We model the SPA pressure dynamics model using first principles and define a large study set of 162 model parameter combinations based on commonly used SPAs and PSS components. We then simulate and experimentally measure the maximum actuation frequency in these parameter combinations, while additionally defining experimental protocols for flow characterization of PSS components and valve control strategy for maximizing actuation frequency. Results from experiments and simulations show good agreement, depicting the trends of how different parameters affect SPA performance. An interesting observation was that for a set of SPA size, tubing length and valve flow capacity, there exists a unique optimal tubing diameter that maximizes the actuation frequency. By further analyzing air and energy consumption, this work allows us to define and solve a multi-objective optimization problem to select and control PSS components to optimize SPA performance and portability simultaneously.

열간 단조금형 이형제 분사용 매니폴드 적층 제조 설계 및 평가

In this study, design for additive manufacturing (DfAM) of release agent injection manifold for hot forging has been performed to achieve weight reduction and flow path optimization. The weight reduction of 53.5% was achieved, thereby enabling the application of stainless steel 316L, which has high strength and corrosion resistance. Lightweight manifolds using Al-Mg-10Si and SUS316L materials were fabricated by PBF-type metal 3D printer. The feasibility test showed that mold life was improved by 14% by solving residual release agent problem. In addition, the flow path optimization results suggested that the flow standard deviation of each outlet dropped sharply from 264 to 75 ㎤/s. This approach demonstrated that DfAM for release agent manifold could be applied to increase mold life and improve product quality and productivity for hot forging.

Optimal power flow-path determination for voltage control in electricity distribution using the modified dijkstra’s algorithm

This paper examines the electric power distribution network system of the Port Harcourt Electricity Distribution Company (PHEDC); its shortcomings, costs and voltage loss in distribution with a view to finding optimal solution through determination of optimal power flow path. The Modified Dijsktra’s Algorithm was applied to generate optimal flow path model of the distribution network with seven (7) nodes from Afam Thermal Power Station (source) to the Calabar Distribution Centre (destination) via the interconnected substations. The structural design of the PHEDC distribution network and a review of relevant literatures on shortest path problems were adopted. The modified Dijkstra’s algorithm was simulated using JavaScript and is able to run on any web browser (Google Chrome, Mozilla Firefox, etc). It was applied to a practical 330kV network using the relevant data obtained from the company and the result shows the negative effect of distance on voltage quality. It was observed that the Modified Dijkstra’s Algorithm is suitable for determining optimal power flow path with up to 98 percent level of accuracy because of its suitability for determining the shortest route in both transportation and power energy distribution as well as its overall performance with minimal memory space and fast response time.

Flow Path Optimization Design of Labyrinth-type Regulator Throttle Disc

Flow Path Optimization Design of Labyrinth-type Regulator Throttle Disc

Optimal design of variable-path heat exchanger for energy efficiency improvement of air-source heat pump system

The optimal number of paths for the heat exchanger of an outdoor unit of a heat pump system depends on whether this heat exchanger functions as a condenser or an evaporator. A variable-path heat exchanger (VPHE) is proposed that can provide an optimal flow path for both condenser and evaporator conditions with one heat exchanger. The performance of VPHE was numerically analyzed, and the results showed that both the heat transfer capacity and pressure drop of the VPHEs increased. The performance of a VPHE with an upper and lower region ratio of 34:24 was enhanced by 22.1% in terms of heat transfer capacity per pumping power. Based on numerical simulation results, the potentially optimal refrigerant flow path was selected and VPHEs were manufactured to be incorporated into a heat pump system. The performance of the heat pump was experimentally measured under heating conditions, standard cooling conditions, part load cooling conditions, and overload cooling conditions. It was demonstrated that the COP of the heat pump employing VPHEs was increased by 15% under the standard rating condition and by 23% under part load cooling condition.

ВЫБОР И ОПТИМИЗАЦИЯ ОСНОВНЫХ ПАРАМЕТРОВ ТУРБОКОМПРЕССОРОВ ПРИ ПРОЕКТИРОВАНИИ И ДОВОДКЕ ГТД

The choice and optimization of the rotational speed, the number of stages, the axial velocities distribution, reactivity, diametric dimensions and flow path shape, the blade rows width, changes in the height of the flow path in the compressors and turbines of the gas turbine engine are considered. The method for determining the total pressure recovery ratio and its relationship with the efficiency of blade rows, stages, compressors and turbines is proposed. It is shown that with the same value of this indicator in these elements, the maximum efficiency of compressors and turbines in the composition of turbocompressors is achieved. It is proposed to use this indicator at an early design stage to determine the optimal stages number and the work distribution between them, the change in work along the flow path height. It is shown how the position of the points for the stages and the optimal flow path shape are determined on the Smith diagrams. Various methods are proposed for parameters choosing of the blade profiles for the first, last and for intermediate steps. It is shown how these methods are used when fine-tuning compressors and turbines based on the results of GTE tests. The results of approbation of the developed design and refinement methods are given on examples of changing the geometry of the blade rows and the flow path in the replaceable flow path of the centrifugal blower for the R-16 "Ufa" gas compressor unit, the refinement of the 3-stage LPC for perspective two spool turbofan engine, comparison with the results of simulation in the DVIGw system , 2D and 3D CAD / CAE-modeling.

Identifying the Optimal Path and Computing the Threshold Pressure for Flow of Bingham Fluids Through Heterogeneous Porous Media

Understanding flow of non-Newtonian fluids in porous media is critical to successful operation of several important processes, including polymer flooding, filtration, and food processing. In some cases, such as when a non-Newtonian fluid can be represented by the power-law model, simulation of its flow in a porous medium is a straightforward extension of that of Newtonian fluids. In other cases, such as flow of Bingham fluids, there is a minimum external threshold pressure below which there would be no macroscopic flow in the porous medium. Computing the threshold pressure is a difficult problem, however. We present a new algorithm for determining the threshold pressure for flow of a Bingham fluid through a porous medium, modeled by a pore-network (PN) model. The algorithm, the ant colony optimization (ACO), is described in detail and together with the PN model is used to determine the minimum pressure for flow of Bingham fluids in a heterogeneous porous medium, the Mt. Simon sandstone, whose PN and morphological properties were extracted from the sandstone’s image. To assess the accuracy and computational efficiency of the ACO algorithm, we also carry out the same computations with two previous methods, namely invasion percolation with memory (IPM) and the path of minimum pressure (PMP) algorithms. The IPM does not guarantee identification of the optimal flow path with the minimum threshold pressure, while the PMP algorithm provides an approximate, albeit accurate, solution of the problem. We also compare the computational complexity of the three methods. For large PNs, both the IPM and PMP are much less efficient than the ACO algorithm. Finally, we study the effect of the morphology of the pore space on the minimum threshold pressure.