Inlet Shape Research Articles

Development of operable modular louvers Sited in a single-sided ventilated room through 3D parametric optimization

The current design practices of buildings to respond to environmental inputs have led to operable envelopes with external louver blinds systems. The key aspect of any openable louver flap design is to optimize inlets that might induce ventilation for occupants with low indoor airflow. Computational Fluid Dynamics (CFD) in 3D parametric modeling investigated the influence of openable louver inlet geometries (right trapezoid) and positions in a ventilated room. A single-sided ventilated room designed with two mirrored split blocks of inlets attached to that wall perpendicular to the wind was employed for this study. Twenty-eight different inlet shape geometries with their cross-sectional changes were investigated. In addition, the inlets' rotation, orientation, and elevation differences were also studied. Wind tunnel experiments were conducted to measure airflows inside the model room to validate the CFD simulations. A discernible impact was observed when the inclined side of the right trapezoid was oriented upward or downward, where inlet flaps open to the sides of the window. The mean air velocity in the ventilated room becomes more than double when inlet flaps open to the sides of the window, where the elevation difference in the inlet blocks introduces the pressure difference compared to no elevation difference in inlets. This study guides into refining an operable modular louver design to enhance air circulation and natural ventilation in dwelling spaces.

X-ray Pelvimetry Has No Impact on the Outcomes of Trial of Labor after Cesarean Delivery: A Retrospective Single-center Study.

Few studies have examined the relationship between pelvic size and the success or failure of trial of labor after cesarean delivery (TOLAC). Here we aimed to determine whether pelvic size and morphological data obtained from radiography contribute to the first successful TOLAC. This retrospective single-center observational study enrolled pregnant women who underwent TOLAC between 2010 and 2021. The results of X-ray pelvimetry data, including obstetric conjugate (OC), transverse diameter of the pelvic inlet (TD), anteroposterior diameter of the pelvic inlet (APD), shape of the pelvic inlet, and other obstetrical clinical data, were compared between the success and failure groups. Seventy-five patients in successful group after excluding 35 patients with previous successful TOLAC, and 21 patients in failure group were eligible. The failure group had a higher rate of previous cesarean sections due to failed labor trials (p = 0.042) and heavier newborns (p = 0.014). OC, TD, and APD on X-ray pelvimetry did not differ significantly between the two groups nor did the shape of the pelvic inlet affect the success rate for TOLAC. The generalized linear model identified a history of failed trials of labor as a significant predictor of failed TOLAC (odds ratio, 0.26; 95% confidence interval 0.071-0.923; p = 0.037), whereas no pelvimetric parameters were found. Pelvic size and morphological findings have no discernible impact on the outcomes of TOLAC. The universal application of X-ray pelvimetry in all women attempting TOLAC may not have significant clinical relevance.

Comparison between using inlet circular jet and elliptic jet in combustion chamber by using twin jet flow propane and methanol

The current work aimed to improve the combustion behavior of a non-premixed twin-jet inlet. The effect of fuel and air inlet shape under different velocities was studied using ANSYS as the process takes place in species transport and finite rate/eddy dissipation, and the flow is considered to be turbulent. Two different shapes (circular–circular and circular–elliptic inlet jets) were investigated, and the results show that the behavior and intensity of the fire are affected by variations in the speed and, geometry of the inlet which affects temperature, heat release rate, combustion efficiency, and equivalent ratios. The optimum air/fuel velocities were found to be 2.5/1.5 with circular–circular inlet jets.

Study on spray characteristics of a compact pressure swirl nozzle integrating tangential inlet flow channel and swirl chamber

Pressure swirl nozzles are widely applied in various heat and mass transfer applications due to advantages of reliable performance, simple structure, and easy processing. However, the complex design of the nozzle structure makes it difficult to miniaturize the pressure swirl nozzle, which restricts its use in limited spaces. In this study, a compact pressure swirl nozzle is proposed by merging a swirl chamber with the tangential inlet flow channel, addressing the issue of liquid atomization in limited spaces. The key geometric parameters are determined based on the internal flow properties by swirl chamber simulation. A spray test bench utilizing a phase Doppler particle analyzer and a high-speed camera was built to study the effect of pressure drop, geometric size, and nozzle inlet shape on spray characteristics. The simulation results show that the nozzle diameter and inlet shape are the main factors affecting flow in the swirl chamber. The experimental results further demonstrate that increasing nozzle diameter increases flow rate and spray cone angle, causing the droplets to move to the spray edge. The spray characteristics are affected by the inlet shape of the nozzle hole: radial velocity and particle size show a wider range of change with a funnel-shaped inlet. Axial velocity and pressure drop are obviously affected by a cylindrical-shaped inlet. This study provided a new design approach for pressure swirl nozzles and achieved flow rate of 5–35 l/h and Sauter mean diameter below 40 μm with an overall weight of 12 g. This compact nozzle construction is a reference for the design of atomizing nozzles in limited spaces.

Numerical Simulation of Thermal Flow Model Under Fluid Mechanics

The internal flow field of vertical water vapor waste heat boiler was studied by numerical simulation. In this project, the RNGk-ε turbulent flow model and Lagrange stochastic trajectory model is used to numerically simulate the gas-solid flow in a direct pressure water vapor waste heat boiler. The influence of the inlet shape, flow rate and outlet clearance of cooling water on the flow and heat transfer performance of cooling water in the cooler was analysed. It is found that the use of three inlet design can improve the water side cooling efficiency, and make the flow rate and temperature distribution in the cooling chamber more uniform. The optimal cooling water volume is 200 tons/hour in the current 2-stage cooling inlet pipe type.

Study on static and dynamic characteristics of water-lubricated hydrostatic thrust bearings – Effect of feed hole inlet shape on bearing characteristics

Recently, water-lubricated hydrostatic bearings have been attracting attention. However, when water is used as the lubricating fluid, the flow velocity of the feed hole used as a restrictor is higher than that of conventional oil-lubricated hydrostatic bearings, resulting in a larger feed hole inlet flow velocity, making it difficult to analyze its characteristics using conventional hydrostatic bearing analysis methods. Therefore, in this study, a general-purpose fluid analysis tool has been used to numerically analyze the internal flow of two types of pocket-type water-lubricated hydrostatic thrust bearings with different feed hole inlet geometries and found that the pressure loss at the feed hole inlet is large for water-lubricated bearings and that the flow inside the feed hole is different from that of oil-lubricated hydrostatic bearings. The orifice effect at the feed hole inlet is found to account for most of the restrictor function. Furthermore, it was shown that the pressure loss at the feed hole inlet can be increased by adopting a right-angle inflow structure for the feed hole inlet geometry, which can improve the static and dynamic characteristics of the bearing.

The Discharge Coffecient for Shaft Spillway According to Inlet Shape and Tail Water Conditions

The Discharge Coffecient for Shaft Spillway According to Inlet Shape and Tail Water Conditions

Analysis of Flow Characteristics at the Inlet of a Circular Involute Variable Wall Thickness Scroll Expander

This paper mainly studies the effects of the inlet shape on the internal flow field and the output characteristics of a scroll expander. Based on circular involute variable wall thickness scroll profiles, three inlet working cavities are numerically simulated using the CFD method and dynamic mesh technique, thus obtaining the internal flow field, the inlet flow rate, the transient gas force, and the change rule of inlet power loss in the working cavity. The results show that the pressure distribution in the working cavity of the scroll expanders with elliptical and double circular groove inlets is more uniform than that in expanders with circular inlets. The high-pressure gas impacting the wall of the scroll teeth at different speeds results in a serious loss of mechanical energy of the gas and a large amount of swirling phenomena in the working cavity. Compared to the circular inlet, the output torque and inlet flow rate of scroll expanders with double circular grooves and elliptical inlets are increased, and the inlet power loss is decreased by more than 40%. Therefore, the double arc groove and elliptical air inlet provide superior performance compared to conventional circular air inlet scroll expanders.

Study on the non-premixed combustion characteristics and exergy analysis of H2/Air in vase-shaped micro combustor

The micro thermophotovoltaic system (MTPV) based on H2/Air combustion has the advantages of high energy density, long-lasting and small-scaled. However, there are still some challenges in combustion stability and safety due to short residence time, large heat dissipation, and flashback. For this reason, a non-premixed micro-combustor with tangential inlet and vase shape is proposed in this paper. The tangential inlet can replace the swirler to form a swirling flow and the vase-shaped channel is designed as a gradual expansion and shrinking tube. The effects of the tangential inlet, equivalence inlet velocity, and key parameters of structure on non-premixed combustion characteristics were numerically studied. The energy transfer path and exergy efficiency were analyzed. The results showed that the vase-shaped micro combustor has a higher blow out limit, and much greater exergy and exergy efficiency than the conventional combustor. With the increase of equivalence inlet velocity, the exergy increases while the exergy efficiency greatly decreases. With the decrease in tangential inlet size, the flame temperature and exergy decreased while the exergy efficiency increased significantly. The tangential inlet can promote the mixing effect in the back-flow region, but the exergy and exergy efficiency decrease. The blow out limit increases with the increase of R3/R1 (maximum channel radius/inlet-1 radius) while the efficiency greatly decreases.

Experimental proof-of-concept of the effect of inlet geometry on excavation forces and their reduction for small-scale continuous excavators

Future in situ resource utilisation (ISRU) lunar mission concepts will require mechanisms that allow the available feedstock–mainly the lunar regolith–to be extracted from the lunar surface. Such extraction techniques in the reduced gravity environment of the Moon will need to minimise excavation forces, due to mass restrictions for robotic landers/vehicles and the large financial implications of placing cargo onto Earth’s satellite. An investigation of necessary excavation forces, both horizontally as well as vertically, for small-scale continuous lunar excavation systems based on their geometric inlet shapes, cutting angles, and digging depths has been undertaken. The use of vibration to disaggregate lunar soil and to reduce the necessary forces is explored as a proof-of-concept. Tests performed in a large analogue testbed have shown that the optimisation of the cutting geometry is crucial, as it inherently influences the necessary forces or even prevents deeper cuts into the soil. Our experiments indicate that shallow cuts (low digging depth) into soil at shallow angles are beneficial, and that the piling up of large surcharge masses must be avoided. Critically, applying vibration to cutting edges seems highly beneficial, as the achievable force reductions of up to 50% in the tested conditions far outweigh the additional power requirements. To make these implications immediately applicable to a wider audience, an estimation of available traction forces for certain robotic vehicles based on their mass is added for comparison.

Influence of Chemical Treatment of Natural Fibre using Shape Memory Alloy for Aeronautics

This article offers a thorough review of shape memory alloys' (SMAs') uses in the Space research field. The utility of SMAs in a variety of applications, including morphing wings (using both experimental and modelling methods), customising orientation and inlet shapes for various propulsion systems, implementing flexible chevrons to improve thrust while lowering noise, and reducing overall power consumption, is the main topic of this paper. The use of SMAs in applications in space is also covered in the paper, including how they may be used to create low-shock launchers, isolate micro-vibrations, and enable self-deployable solar sails. The essay also emphasises the novel structures and tools made possible by SMAs. One noteworthy method covered in the article is putting SMA wires in the laminate's midplane and embedding them into the fabric a layer of composite laminates. When compared to traditional composite constructions, the incorporation of SMAs into composite has shown better damage resistance and ductility. The reaction of a bright hybrid plastic composite plates to a very low-velocity impact is examined experimentally and numerically in this paper, which highlights the benefits of inserting SMA wires. Among these benefits are improved damage resistance, better ductility, higher composite hardness, and increased energy absorption before failure. Shape memory alloy (SMA) are the subject of extensive industrial applications and ongoing study in the field of materials. Its two distinguishing qualities, the shape memory impact and superelasticity, are mostly to blame for this. A composition's structure that suffered a phase transition as a result of temperatures, pressures, mechanical forces, and other factors is implies to as having a "shape memory effect". The composition, despite the very significant plastic deformation to which its surface is susceptible to, may recover to its original form under the influence of temperature as well as other factors.

Calculation of Head Losses and Analysis of Influencing Factors of Crossing Water-Conveyance Structures of Main Canal of Middle Route of South-to-North Water Diversion Project

The main canal of the middle route of the South-to-North Water Diversion Project has the risk of excess head loss in crossing water-conveyance structures, but the assessment of this risk faces difficulties such as the lack of sufficient monitoring points inside the structures, the current water-conveyance flow rate being lower than the design maximum flow rate, and the lack of verification of monitoring data. Monitoring data of the main canal were collected in 2022, prototype observations were carried out, the monitoring data were verified, and a method for calculating the head loss using the combined head loss coefficient was proposed. The assessment of 143 structures showed that 40 structures had excess head losses, including 31 inverted siphons, four aqueducts, four underdrains, and one culvert. The 143 structures had a total residual head of 3.05 m, accounting for 9% of the distributed head. In addition to natural aging, freshwater mussel and algal attachment, sediments, and undesirable flow regimes were all important influencing factors that caused the head loss to increase. It is recommended to take measures such as regular removal of sediments and algae and freshwater mussel attachments, optimization of inlet and outlet shapes, and application of roughness-reducing materials.

Examining the Impact of Inlet Shape on Nasal Cavity Flow Field: A Computational Investigation

In numerical calculations, entrance lengths and volumes upstream of the control volume are commonly used to steady the flow and obtain more accurate results. This paper discusses the effect of the geometrical shape of the inlet on the results of the flow field. The study presents the results of a Computational Fluid Dynamics (CFD) simulation of a real model of nasal cavity created from CT images of one patient. Furthermore, the spherical and cubic volume in front of the nostril entrance is modeled. Within the results, the flow fields are observed in planes across the entire sinus from the nostrils up to the nasopharynx. The resulting flow fields from all the three models are compared with each other. The effect of the geometric shape before the entrance to the nostrils is discussed considering the model without the modeled volume. The model created from the CT data of one patient was modified in CAD software to create differently shaped volumes in front of the nostrils. The CFD calculations were performed using Ansys Fluent 2021 R1 software.

An Integrated Passive Cooling System for Thermal Comfort

Abstract: In the hot and humid environment of Indian summers, a conventional cooling system is too expensive for most people. In this project, Passive cooling systems which consume less power, are more efficient, cost less, and make very little noise are used. After researching various passive cooling techniques in isolation and running simultaneously, we aim to develop a system that is cost-effective and efficient at cooling the Indian household. The focus of this project is on the four major types of passive cooling techniques, they are radiant cooling, solar chimneys, wind catchers, and shading devices. Supplementary techniques like terrace cooling are also included. The initial analysis and study of the windcatcher system with various heights and inlet shapes have been conducted. A software model has been generated using fusion 360, analyzed in Ansys fluent, and results were recorded.

Analysis of influencing factors on displacement sampling performance of deep-sea gas-tight sampler

The collection and research of deep sea water has always been a hot and key topic in the field of marine research. Collecting seawater samples that can truly reflect the in-situ water composition information through a deep-sea sampler is an important technical means in the field of deep-sea exploration. The deep-sea water sampler designed in this subject samples deep-sea water by displacement sampling. According to the jet theory, the method of numerical calculation combined with experiment is adopted, the influence of indirect displacement, shape and diameter of sampling inlet, Coanda distance, sampling rate and other factors on the displacement effect is analyzed in this paper. The results of the study demonstrate that at low speed, multiple displacements can improve the displacement effect. In the high-speed sampling state, a single displacement method should be adopted. The design of making the sampling port as close as possible to the wall of the sampling cavity helps to strengthen the plane jet to improve the displacement efficiency. The displacement efficiency can be slightly improved by using the rectangular sampling inlet and outlet. As the extraction speed increases, the liquid mixing area becomes larger. Through discussion and comparison with similar research at home and abroad, the sampler has good performance and high sampling purity. The analysis of the effect of changes in sample temperature on the sampling displacement efficiency will be performed in the future. The research on the thermal insulation performance of the sampling channel will be put on the agenda.

Numerical Study on Isokinetic Samplers with Different Nozzle Geometries

When collecting dust samples from coal-fired power plant chimneys, a nozzle specially designed with an inlet shape of circle type is used for constant velocity suction. However, it is cumbersome to use nozzles with different areas depending on the flow rate. In this study, the effect of the nozzle inlet shape of the isokinetic sampler on the performance of constant velocity suction was evaluated through simulation. The simulations were conducted using the realizable k−ε model, which is known to be suitable for separation flow analysis for particles of 1–50 μm. The turbulent flow fully developed before reaching the inlet of the sampling probe, and the flow rate was set under the condition that the uniformity was secured at approximately 92% at least. The aspiration ratio was employed for evaluating the degree of constant velocity aspiration of the isokinetic sampling probe. It was found that the larger the particle diameter and the faster the flow rate, the larger the aspiration ratio for both the circular and ellipsoidal inlets. In particular, compared with the circular inlet, the aspiration ratio of the sampler with ellipsoidal inlet was closer to 1 in the free-flow velocity range, from 5 to 15 m/s. For this reason, if the ellipsoidal inlet nozzle is used by adjusting only the length parallel to the major axis, the maintenance cost is expected to be reduced compared to the circle-type nozzle.

A new distortion evaluation method based on geometric association for arbitrary cross-sectional shape of inlet

The distortion flowfields generated by convoluted inlets are major factors that compromise the stability and performance of the downstream engine. For better understanding the distortion evolution, the total pressure distortion from the arbitrary cross-sectional shape of inlets was efficiently calculated based on geometric association. First, the Poisson equation was solved to generate a grid on the original, arbitrarily shaped, non-circular plane; then, a previously simulated dataset was used as a sample to interpolate the grid, whose nodes were mapped into a circular plane according to the principle of equal areas of rings and blocks. Finally, the traditional distortion descriptors were used to evaluate the distortion of the newly generated plane. The proposed method guarantees that both the total pressure recovery coefficient of the transformed crossflow plane and the contribution of this coefficient from each grid unit remain constant. This method was also applied for the flowfield analysis of serpentine and submerged inlets; the various forms of distortion along the ducts were studied. The total pressure distribution coefficient DC(60) distributions along the internal flow direction differed completely under different exit Mach numbers and their drastic changes were located at the severe bends or expansions of the inlet profile. Such innovation in distortion evaluation can provide insights into flow distortion in various inlets and enable better integration between inlets and engines.

A review of the research status of scroll expander

In order to solve the problem of energy crisis and take the road of sustainable development, the development of renewable energy and recycling of low-grade waste heat have attracted more and more attention. As a new type of volumetric energy conversion device, scroll expander is wi dely used in Organic Rankine Cycle (ORC) waste heat recovery, because of its advantages such as small size and so on. Scroll profile is one of the main factors affecting scroll expander performance. Compared with the traditional constant section scroll profile with same suction volume, volume ratio and shell size, the new type of variable section scroll profile could reduce scroll tooth height, better mechanical properties and improve efficiency, therefore making it more suitable for working under complex operating conditions. In order to reduce the head invasion rate, airflow friction factor, the power loss at the air inlet, and improve the pneumatic power conversion efficiency, a new head correction method is proposed. Although R123, R134 and R245 are the most commonly used working medium in scroll fluid machinery, the selection of working medium in scroll expander is still a key problem. The overall performance of the scroll expander can be improved by designing different inlet shapes and positions or double-symmetrical exhaust ports. The radial leakage caused by axial clearance of scroll expander can be improved by developing new scroll profile to reduce the length of radial leakage line and optimizing the design of scroll top sealing mechanism. The tangential leakage caused by radial clearance can be improved by enhancing the manufacturing precision and installation accuracy of scroll plate and designing the radial variable mechanism. At present, fewer research has been carried out on the leakage of scroll expander. Therefore reducing the leakage loss to improve the performance of scroll expander is of great significance in the future research.

활어 이송용 스크류원심 임펠러 블레이드 입구 형상에 따른 펌프 수력 및 흡입 성능

A screw centrifugal pump is a non-clog type pump known as the sewage pump to transfer solids such as rags, hair, clusters of stringy material, and digested sludge applications. With the large and open channel from suction to discharge, the screw centrifugal pump shows better solids transferring capability, even the sensitive products such as food (tomato, potato), live fish, eel, shrimp. However, the impeller blade inlet of screw centrifugal pump with the high rotation speed can damage the live fish or food. Therefore, in this study, the impeller blade inlet shapes are investigated for their influence on the performance of the live fish transfer pump. The straight, concave, and convex blade inlet shapes are created. Numerical analysis was conducted to study the pump hydraulic and suction performances according to the impeller blade inlet shapes of the screw centrifugal pump.

Effects of tubes with different inlet shapes on the shock wave and self-ignition induced by accidental release of pressurized hydrogen

Spontaneous combustion caused by accidental leakage of high-pressure hydrogen affects the safe use of hydrogen energy. In this paper, the self-ignition of pressurized hydrogen discharged into tubes with different inlet shapes was studied experimentally. Inlet shapes include circles, square and triangular. The circular shapes are available in two different diameters, one is the same as the tube diameter, and the other is smaller than the tube diameter but has the same cross-sectional area as the square and triangle. Pressure transducers and photoelectric sensors are used to record pressure variations and self-ignition inside the tubes, respectively. The results show that pressure dead zone exits in the near field of the inlet as the inlet area decreases. The range of the pressure dead zone grows with increasing release pressure, which is not conducive to the occurrence of auto-ignition. In addition, under the same inlet area and release pressure, the inlet shapes play an important role in the characteristics of shock wave. It was found that the intensity and mean speed of the shock wave are greatest in tube with circular inlet, followed by the square, and least in the tube with triangle. Moreover, compared to the tube with circular inlet, the likelihood of spontaneous combustion is reduced for the tube with non-circular inlet. Among them, spontaneous ignition did not occur even though the pressure release was up to 11 MPa in the triangular inlet tube. It indicates that the better suppression of self-ignition can be achieved by changing the inlet shape of the tube.