Supply Channel Research Articles

Assessment of a virtual boundary concept for efficient modeling of turbine film cooling

Film cooling is one of key technologies advancing the performance of gas turbine engines, which is extensively applied in the hot turbine component for thermal protection by injecting cooling air from numerous film holes. To achieve an optimal film cooling scheme, many iterations of the position, the diameter, and the orientation of the holes through computation simulations are required to well fit the aerodynamic profiles of the turbine blades. However, a conventional computational simulation that resolves each individual hole and its coolant supply channel implies substantial costs of computation resources. In this study, a novel film cooling modeling method that uses a virtual boundary to represent film holes is assessed by comparing to the conventional computational simulation in two representative test cases, involving flat-plate and turbine endwall inlet film cooling. Relevant experiments are carried out to provide experimental data for verifying the approach at various coolant injection rates. Generally, the virtual boundary model produces rather equivalent results to those predicted by the conventional simulation method. Though coolant concentration downstream of the holes is over-estimated by the virtual boundary model due to neglected in-hole mixing, the overall flow fields and film cooling performance are well captured, showing the feasibility of the novel strategy in accurately modeling film cooling in a much more efficient way by saving computational efforts. This novel concept thereby allows designers to modify the film hole geometries independently of the blade geometry and thus, is helpful to accelerate the design process of a film-cooled turbine or to assess multiple film cooling configurations more quickly, as compared to a conventional computation simulation.

Wicking-controlled interfacial water content for highly efficient solar desalination

Solar-driven interfacial evaporation offers a potential solution to address global freshwater scarcity. However, the water-thermal-vapor-salt imbalance issue severely affects the operating efficiency of the evaporator. This research examines the correlation among water supply height, spontaneous wicking rate, and interfacial water content. Subsequently, an engineering strategy is proposed to control the water concentration gradient within a two-dimensional solar absorber with vertical water supply channels. The results demonstrate that the hydrophilicity and internal structure of the material exert a crucial influence on the transport of bulk water. Specifically, longitudinal stripes within the water-conducting material promote a faster wicking rate and higher wicking height. This phenomenon occurs due to the combined effects of capillary forces and gravity, leading to a gradual decrease in liquid saturation along the capillary direction within the water-conducting material. By optimizing the water supply height and rate, the evaporation interface achieves a remarkable water evaporation rate of 1.50 kg m−2h−1. Building on this success, a novel configuration for a flow desalination evaporator is proposed, capable of sustaining the same evaporation rate even when operating continuously for 9 h in saltwater with a mass concentration of 20 %. Overall, this study emphasizes the importance of water and heat balance at the evaporative interface, reconciling conflicting requirements of interface flow and evaporation rate. These findings contribute to the development of highly efficient and reliable evaporators for sustainable freshwater generation.

Provenance and tectonic settings of the lower Permian siliciclastic rocks in central Inner Mongolia: Implications for the evolution of the Paleo-Asian Ocean

The fine siliciclastic rocks of the Early Permian Shoushangou Formation in West Ujimqin Banner, central Inner Mongolia are a hot spot for Late Paleozoic oil and gas exploration and hold key implications for the tectonic evolution during the closure of the Paleo-Asian Ocean (PAO). Therefore, the sedimentary characteristics of the Shoushangou Formation in West Ujimqin Banner, along with the geochemical and Sm–Nd isotopic characteristics of the clastic rock samples in Well MXD1, were investigated to privde additional constraints on its provenance and tectonic background.The mudstones contain large proportions of quartz, feldspars and igneous debris, and the CIAcorr (0.52–0.66), the A–CN–K plot and the lack of Ce anomalies in REE show a weakly weathered provenance and the chemically unaltered parent rocks, suggestive of the proximal deposition and rapid burial. Slip-roll beddings, gravity flow, Bouma sequences and the (trace) fossil assemblages in the profile indicate that the Shoushangou Formation is mainly a shallow- (semi-)abyssal submarine fan and the lithological information indicates the presence of microfaces including main and lesser water supply channels, interchannels, lobes, natural levees. Furthermore, a narrow continental shelf above the submarine fan and the concentrated zircon age population of the Shoushangou formation suggest that the tectonic background is most likely a retroarc basin.The Al2O3/TiO2 ratio (19–24, average 22), the multivariable principal element source identification diagram and the plots of Th/Sc vs. Zr/Sc and Co/Th vs. La/Sc indicate that the source is mainly felsic, with a minor proportion of intermediate rocks. Trace elemental characteristics (e.g., Th, Zr, Sc, Co, Nd, and REE) deomonstrate that the tectonic setting of the Shoushangou Formation is confined by continental arcs.The whole rock Sm–Nd isotopic spectra of the Carboniferous and Permian strata indicate that the Baolidao arc is the main source of central Inner Mongolia. Additionally, the comparison of the Nd model ages and the zircon U–Pb ages of the Baolidao arc and other entities in the Central Asian Orogenic Belt (CAOB) is in support of a prolonged subduction of the PAO since ∼510 Ma, suggesting that the Baolidao arc was developed from the southern continental arc of the original South Mongolia microcontinent. Accordingly, it is suggested that the Shoushangou Formation was deposited in a retro-arc basin which was strongly influenced by the steep subduction of the PAO and the results collectively suggest that the PAO terminated no earlier than the middle to late Permian.

Inventory Management Literature Review: Based on Perishables, Channel Supply, Supply Chain Cooperation

Inventory management is an important problem in the enterprise, inventory is a double-edged sword, if used well, it will be the key to gain profits, if there is a problem, it will also become the last straw that breaks the camel. The inventory problem will be the key to the survival of enterprises. This paper mainly studies the literature of inventory management in the past 5 years, and expounds the inventory problems that researchers pay attention to from the issues of perishable goods and multi-channel supply. The conclusion of this paper has a positive impact on the future supply chain inventory cooperation of enterprises.

Russian industrial companies under the “second wave” of sanctions: Response strategies

The article presents initial findings of a research project aimed at analyzing the impact of the “second wave” of sanctions in 2022 on the behavior of Russian companies, assesses their actions to adapt to the new conditions. This paper is based on survey data collected from managers of 1860 Russian manufacturing companies between August and November 2022. Despite the severity and scope of the sanctions, one third of the companies did not take adaptation measures, particularly local, technologically backward firms without innovative activity. On the whole, firms integrated into the global economy reacted more actively to new threats than those confined to the domestic market. We found significant variability in companies’ responses to the sanctions shock. Four basic quasistrategies of firms’ response are identified. The first one involved reducing current activities, employment, and investments. These actions were most common in industries integrated into global value chains, notably automotive industry and wood processing. The second strategy included simplifying products to reduce dependence on imports, finding new markets, and changing investment directions — typically seen in pharmaceutical firms. The third one consisted of altering supply channels for materials and components, and it was frequently adopted by manufacturers of rubber and plastic products. The fourth strategy focused on digitalization, developing new products, and increasing interaction with authorities. This was characteristic of industries whose markets have carved out niches due to the exits of major foreign players, in particular, manufacture of furniture. We highlight the following recommendations for the state anti-crisis policy: In 2022, the relative success of companies’ adaptation was associated with the implementation of “easy” import substitution. However, in the future there will be a need to prioritize support for the development of domestic technologies and increased access to knowledge. In conditions of high uncertainty, it is crucial to assist companies in building their own value chains, and predictability of government actions appears to be a significant factor in enhancing private initiative.

A qualitative study on the development of short supply channels in the Spanish agri-food sector: Producers’ perspectives and expectations

This study focuses on gaining insight on the current state of implementation and development of short food supply channels (SFSC), as an alternative or complement to long food supply channels. Therefore, the aim of this study is to identify the various challenges, barriers and advantages that Spanish agri-food producers face regarding the use of SFSC. To this aim, 22 in-depth interviews were conducted with Spanish agri-food producers who used SFSC in their businesses. Each interview lasted approximately 30 min and covered all aspects associated with the implementation of SFSC, mainly including the drivers and the barriers they had met. The results show that the implementation of SFSC is mainly driven by consumers’ willingness to pay a premium for their products, which means a higher margin for the businesses, whereas the main barrier refers to transport and logistics, due to the potential impact on costs, quality, and consumer satisfaction. Therefore, the implementation of SFSC in the businesses has had a positive impact on their sales, although effective solutions for more sustainable and efficient distribution systems in the SFSC and more marketing activities are needed to boost this type of supply channel.

Reliability Analysis of Water Supply Channels for Conveying Design Flow

Reliability Analysis of Water Supply Channels for Conveying Design Flow

Foreign trade of the USSR in agricultural products in the period 1941-1945

The object of the study is the import and export supplies of food products, agricultural raw materials and live animals to the USSR during the Great Patriotic War, the War with Japan and until the end of 1945. The subject of the study is the dynamics, trends and patterns of changes in the volume and structure of import and export of various types of agricultural products into the country and changes in the ratio of various supply channels of these products. The main content of the study is the creation of a statistical database based on a number of archival statistical sources containing data on agricultural imports and exports for the specified period and the analysis of this database. The article provides a brief description of the research on the topic of the work and an analysis of archival sources. When creating a statistical database containing data on the natural volumes of imports and exports of agricultural products, methods of historical, source-based and statistical analysis were used. As a result of reviewing the created statistical sample with data on agricultural imports and exports of the country, the following results were obtained containing elements of scientific novelty: 1. The characteristics of agricultural imports are more complete than in most previous studies. 2. The characteristics of the export of agricultural products for these years are given, which is absent in most previous studies. 3. In connection with the above, a more accurate description of the trends in the characteristics of imports and exports of agricultural raw materials and food during the years of the Great Patriotic War and the War with Japan is given, and the share of imports of a number of types of agricultural products in the total domestic production is calculated in a new way.

Research on the Material and Human Resource Allocation in Rural Schools Based on Social Capital Theory

The allocation of resources in rural schools directly affects the quality of rural education development. However, rural schools have long faced inadequacies in both material and human resource allocation. Social capital, as an intangible resource, can play a significant role. This article first analyzes the current problems in the allocation of material and human resources in rural schools, highlighting issues of inadequacy and imbalance. Then, from the perspective of social capital, it analyzes its impact on resource allocation, which can not only expand resource supply channels but also enhance allocation efficiency and promote sharing. In addition, the article proposes strategies and recommendations for leveraging social capital to optimize resource allocation in rural schools. Finally, empirical research using typical cases and questionnaire surveys verifies the effectiveness of social capital in resource allocation. The study demonstrates that social capital can effectively improve resource allocation efficiency and play a crucial role in enhancing rural education development.

The Effects of Channel Supplies on Overall Film-Cooling Effectiveness

Abstract Cooling components in the hot section of a gas turbine are essential to component durability. Common methods of cooling include rib turbulators in internal passages and film cooling on external surfaces. The holes that produce the film cooling are fed from the internal channels often containing ribs. Consequently, there is an interdependence of internal heat transfer and external film cooling. The purpose of this study was to obtain a better understanding of the interaction of ribs and film cooling. To quantify the cooling performance, the surface temperatures were measured, from which overall effectiveness was calculated. For the experiments, additively manufactured test coupons were made of Inconel 718 to match engine Biot numbers. These test coupons had internal feed channels with and without ribs and had both cylindrical holes and meter-diffuser-shaped holes with 15 deg lateral expansion angles and a 1 deg forward expansion angle. A single rectangular channel was one type of feed channel. The other type of feed channel was individual circular channels, with each circular channel supplying an individual film-cooling hole. The experimental results showed that the circular individual channels have 80% higher baseline overall effectiveness than the single rectangular channels without any film cooling. Ribbed turbulators without film cooling also increased the overall effectiveness by 21% for single rectangular channels and by 29% for the circular individual channels compared to the respective non-ribbed channels. While the film cooling increased the overall effectiveness of all geometries, the single rectangular channels had increased overall effectiveness levels by up to twice that of the no film-cooling case. On average, the single rectangular channels had an 80% improvement from film cooling, whereas the individual channel feeds, on average, had only a 50% improvement, given their high baseline effectiveness levels.

Who benefits from postponement in multi-period supply channel optimization?

Duopolistic price-setting supply channels competing in a bilevel framework have been extensively studied in single-period (static) settings. However, such supply channels typically face uncertain and time-varying demand; and thus require a dynamic analysis. Dynamic channel optimization while addressing uncertain demand has received limited attention due to the highly nested structure of the ensuing equilibrium problems. The level of complexity rises when demand is dependent on current and previous prices. We consider a decentralized (non-cooperative) supply channel whose members, a manufacturer and a retailer, competing in a Stackelberg framework, must address the demand for a perishable commodity within a multi-period discrete-time setting. In the first part of the paper, we propose a constructive theorem providing an explicit solution algorithm to obtain equilibrium states at each period. Next, we prove that the resulting equilibria are subgame perfect. In the second part, we allow the retailer (follower) to postpone the supply and pricing decisions until demand uncertainty is resolved in each period. Using subgame perfection of the equilibria, we propose solution algorithms that use the delayed information obtained by the postponement. Our comparative theorems and simulated scenarios indicate that postponement strategies are always beneficial for the follower, and, for a centralized (cooperative) channel. Whereas in a decentralized channel, due to vertical competition, there may be scenarios wherein postponement strategies, i.e., access to extra information, turn out to be detrimental to the manufacturer (leader).

The Influence of Supply Channel Design on the Gas-Dynamic Structure of Air Flow in a Vertical Conical Diffuser

Vertical conical diffusers are used in power engineering, chemical industry, technological processes, and other industries. The efficiency of many machines and pieces of equipment is determined by the gas-dynamic and heat-exchange perfection of processes in diffusers. This study assesses the influence of the air supply method on flow structure in a diffuser. The studies were carried out on a test bench with thermal imaging for air flow rates ranging from 0.018 to 0.057 m3/s (42,500 < Re < 150,000). Two designs were examined: (1) a conventional air supply through one channel from below and (2) a nozzle air supply through four tubes at an angle of 45° to the vertical axis. In addition, the influence of the cross-sectional shape of the supply channels of both designs was studied. It is established that the use of a conventional air supply through one channel leads to the generation of a pronounced central flow along the vertical axis (all configurations of the supply channel) and the creation of stagnant zones in the corners of the diffuser (round and triangular channels; the use of a square supply channel causes the most uniform air distribution throughout the entire volume of the diffuser (while maintaining the central flow). It is found that with nozzle air supply, there are no stagnant zones in the corners and intense air movement generation in the centre of the diffuser (round and triangular tubes) can be observed; the use of square nozzle tubes causes intense flow movement at the base of the diffuser, which quickly collapses upstream, uniformly filling the entire volume of the diffuser’s cylindrical part. The presented data can be useful for designing various machines and pieces of equipment with vertical conical diffusers.

POLISH FOREIGN TRADE OF AGRICULTURAL AND FOOD PRODUCTS DURING THE COVID-19 PANDEMIC

In the research on the impact of the COVID-19 pandemic on the economic situation in agriculture, the demand and supply channels are distinguished. They indicate how restrictions on economic activity translate into the volume and structure of production and the demand for agricultural products. The aim of the research was to identify and assess the impact of the COVID-19 pandemic on Polish agriculture through the transmission channel of foreign trade. The research period covered the years of 2017-2022. The primary research tool used was time series indicator analysis. During the pandemic, changes in foreign trade were limited only to short-term disruptions, which intensified in the first wave of COVID-19 (2020, second quarter). Trade in agri-food products turned out to be more resistant to shocks caused by the pandemic compared to trade in non-agricultural sectors. Therefore, disruptions on foreign markets did not significantly affect the production and economic situation of Polish agriculture. In the second quarter of 2020, the value of exports of agri-food goods decreased by 2.8% compared to the previous quarter. As it comes to other groups of goods, export values were lower by 7.2-40.1%. At the same time, the value of imports of agri-food goods was lower by 6.1% compared to the previous quarter. Imports of other goods collapsed much more severely as decrease in the value of imported goods ranged from 8.4 to 47.4%.

Experimental investigation and correlation analysis of pool boiling heat transfer on the array surfaces with micro-fins using FC-72 for the electronic thermal management

Pool boiling heat transfer characteristics were investigated on the both homogeneous and fractal array micro-pin-finned surfaces using FC-72 as working fluid. Two distinct fractal geometry pattern surfaces (Array4 and Array9) were designed to further explore their boiling heat transfer performance. The effect of different subcoolings (0 K, 15 K and 25 K) has also been analyzed combining fractal array surfaces. Bubble dynamics were captured using a high-speed camera. The results present the the array micro-pin-finned surfaces with less heat transfer area ratio can achieve similar or even higher CHF compared to the uniform micro-pin-finned surface (PF0.3–0.2–2), especially for subcooled boiling (ΔTsub = 25 K). Notably, bubbles nucleate and grow prior to reaching the micro-pin-finned unit region. This phenomenon is evident in visual images, indicating that the fractal array effectively impedes bubble coalescence, particularly during subcooled boiling. Besides, this fractal array surface can provide liquid supply channels and prevent dry-out. The mechanism behind the heat transfer enhancement and CHF triggering is elucidated based on liquid replenishment and bubble coalescence behaviors. A CHF prediction model was established considering the effect of liquid subcooling, rectangular array distribution, and micro-fins feature size. And the prediction results from this model show well agreement with experimental values and data points from literature, with mean absolute deviation being less than ± 15 %.

Stable Communications in Green Unmanned Aerial Relaying Systems

Green unmanned aerial relaying (UAR) systems, featuring solar-powered unmanned aerial vehicles (UAVs) to provide agile and flexible communication services, have recently gained significant attention for their wide applications. Nonetheless, due to the essential dynamics of wireless channel conditions and solar energy supply, maintaining system stability is a critical concern in practical green UAR systems, as fluctuation in these two factors can significantly affect communication performance. To address this issue, this paper proposes a scheme design for stable communications in a UAR system with dynamic solar energy supply and wireless channel conditions. Specifically, we first formulate an optimization problem, called OFL, to control the power allocation and flow data rate assignment to minimize long-term time-averaged energy consumption while ensuring the demanded data rate and system stability. Considering that solving OFL needs complete prior information about the solar power supply and wireless channel conditions, which is hardly acquired, we then explore the Lyapunov theory to transform OFL as an online optimization problem, called ONL. To find the solution to ONL, we subsequently design a distributed algorithm that enables each UAV to make its own decision locally, thus reducing the computational overhead of each UAV. Particularly, we prove that stability can be guaranteed by employing the designed algorithm. Extensive simulations are conducted to show the performance achieved by the proposed scheme.

Comparison of different taxation models on cross-border supply chain decisions: Considering disruption forecast and cost differences

In this paper, we consider disruption forecast and channel operating cost differences in a cross-border dual-channel supply chain and construct a dual-channel supply chain strategy game model under different taxation models. We compare the optimal pricing, order volume and profits of supply chain members under four strategies. We also analyze how the tariff rate and channel cost difference coefficient affect each member’s optimal decisions and profits. First, we find that under different taxation models, the impact of tariff rate on optimal order volume is different, but it always has a negative effect on optimal wholesale price. Second, in some threshold intervals of the channel cost difference coefficient, the size relation of optimal pricing is consistent with order volume under either taxation model, regardless of whether to wait for a disruption forecast. Finally, when the supply chain disruption probability and channel cost difference coefficient take different combinations, with the change in tariffs, the e-retailer and overseas manufacturer tend to adopt different strategies.

Разработка общего критериального уравнения расчета теплоотдачи к углеводородным и неуглеводородным средам при их естественной конвекции в условиях локального осадкообразования

The paper presents a new general criterion equation for calculating heat transfer under conditions of natural convection of the hydrocarbon and non-hydrocarbon media with local deposit formation on the heat exchange surface. Information sources on the research topic were analyzed. Examples of deposits in certain power plants and jet engines are provided. Main factors influencing the carbon-containing deposits on the heated walls of the fuel and coolant supply channels are considered. The new equation for calculating heat transfer was obtained based on a new deposit formation similarity criterion created by the author of this article, which simultaneously takes into account both the thermal and electrochemical nature of this process. Values of the new electrochemical numbers used in the calculation and included in the deposit formation similarity criterion were found for the carbon-containing deposits in the kerosene media and for the salt deposits (NaCl salt). Results of the experimental studies were generalized in the TS-1 kerosene media, salt solution and air with local deposit formation on the heat exchange surface. Some generalization results are presented in the corresponding graphs.

Water-Supply Potability Status of Bangladesh University of Health Sciences (BUHS)

Water that is free of disease-producing microorganisms and chemical substances harmful to health is called potable water. Drinking water quality has a microbiological and a physicochemical dimension. In public water supply systems, water should be disinfected. This observational study was conducted through a multiple-tube method. And the water supply channel of Bangladesh University of Health Sciences (BUHS) served as the study's sample. Using an aseptic procedure, 105 ml of water from various sources is collected for each sample on a conical flask. The selected sample was from the four different water supply points at BUHS institution. From sample 1, the MPN (Most Probable Number) index we found the combination of positive sets (0-1-0). The MPN value per 100ml water is (1). From sample 2, the MPN index we found the combination of positive sets (1-1-1). The MPN value per 100ml water is (5). From sample 3, the MPN index we found the combination of positive sets (1-2-1). The MPN value per 100ml water is (7). From sample 4, the MPN index we found the combination of positive sets (0-1-0). The MPN value per 100ml water is (1). In Dhaka city, there is a possibility of contamination of the water sources. Bangladesh University of Health Sciences is a renowned institution with a big number of staff. So, it is important to examine the water condition in this institution. Our work and research reflect a little about it. Gladly and hopefully, we found that there is no pathogenic organism in the water of this institution which is used every day and everybody drinks.

Cooling performance of film-cooling holes fed by channels of various shapes

Internal and external cooling is pertinent to maintaining operable surface temperatures of hot-section gas turbine components. Film cooling on the external surfaces is supplied from cooling passages placed inside of the blades and can affect the external film-cooling performance. Assessing internal cooling designs that were once difficult to investigate because of the complexity and costs of manufacturing cast turbine blades is now possible to more quickly and less costly through additive manufacturing (AM).This paper provides results and analysis of an experimental and computational study of the cooling performance of meter-diffuser shaped film-cooling holes fed by a range of individual channel shapes with different cross-sectional shapes: circle, hexagon, pentagon, ellipse, diamond, square, rectangle, trapezoid, triangle – vertex up, and triangle – vertex down. These geometries were made possible through the use of AM. The perimeter, and consequently the surface area of the supply channels to the cooling holes, was maintained constant between the different channel shapes. The predictive computational results showed that the shape of the channel affects the secondary flows through the hole that in turn affects the overall film cooling as determined experimentally. The triangle – vertex up created flow structures in the diffuser-shaped cooling hole that caused the coolant jet to create a film on the surface with wide lateral spread; whereas the triangle – vertex down created flow through the cooling hole that caused the jet to fully detach at the same blowing ratio. Consequently, the triangle – vertex up had a 14% improvement in overall effectiveness over the triangle – vertex down and a 33% improvement over the circle which had the lowest overall effectiveness of all the tested shapes.

Heat transfer in a rotating impingement cooling channel with concave target surface

Jet impingement cooling is a common technique for cooling the leading edge of turbine blades that experience high thermal loads. This study examines the effect of rotation on jet impingement cooling by conducting experiments in a rotating channel with a concave target surface. The dimensionless parameters of the jet configuration are 3 for both jet-to-jet spacing and jet-to-target surface spacing. The jet rotation number and jet buoyancy number reach a maximum of 0.26 and 0.63, respectively. The jet Reynolds number ranges between 5,000 and 15,000. The results show that a large vortex is generated in the supply channel due to the Coriolis force, which changes the mass-flowrate distribution in each jet hole. Therefore, the heat transfer in both ends increases while that in the middle region decreases, resulting in a U-shaped heat transfer distribution in the radial direction. In addition, the rotational Coriolis force is the dominant factor that affects the rotating jet impingement cooling, while the buoyancy force can affect heat transfer at high rotation numbers. The rotation-to-stationary Nusselt number ratio is defined to separate the effects of the Reynolds number, thus, the heat transfer correlations are developed between Nusselt number ratio and rotation number.