Inlet Design Research Articles

Flow models of perforated manifolds and plates for the design of a large thermal storage tank for district heating with minimal maldistribution and thermocline growth

Large water tanks are used as thermal energy storage components in district heating systems to store sensible heat produced by intermittent energy sources and to decouple the production of thermal energy from its demand. Good thermal stratification is crucial for energy storage efficiency, thus flow maldistribution and mixing of water layers at different temperatures should be minimized. This paper proposes an innovative internal flow distribution configuration for a large-size thermal energy storage, and develops new simplified analytical models for the choice of its design parameters. In the novel configuration, water is injected into (and collected from) the cap volumes of the tank by flowing radially inward (outward) through several small orifices of a peripheral toroidal manifold. Two horizontal perforated plates cover the full cross sections downstream of the manifolds and rectify the vertical flow, thus reducing mixing. Uniform perforation pitch was analytically demonstrated to be the most reasonable solution both for the toroidal distributors and for the rectifying plates. A 1D model was developed to predict the time evolution of the vertical temperature distribution in the tank. The turbulence-related parameters that could not be inferred from the existing fluid-mechanics literature were initially estimated with CFD simulations. The results of CFD-calibrated model were then compared to experimental data obtained from a full-scale large water-tank facility recently built in Brescia according to the proposed design. After a re-calibration of the exponent defining the decay of homogeneous turbulence downstream of the perforated plates, good agreement was found between measured and predicted vertical temperatures. With the novel inlet design, a thermocline of about 0.5 m is established immediately downstream of the perforated plate, and remains practically constant along time. The model is important to minimize and control the thermocline thickness so as to maximize the recoverable thermal energy, not only at the tank design stage but also to identify optimal loading and unloading protocols.

Assessment of a catalytic plate reactor with in-situ sampling capabilities by means of CFD modeling and experiments

A catalytic plate reactor with a small movable sampling capillary enables us to gather a significantly larger set of kinetic data for the parameter estimation than using a typical steady-state packed-bed reactor with end-of-pipe measurement. In this study, a reactive three-dimensional CFD model developed with catalyticFOAM is validated by experimental axial gas species concentration profiles and then used to investigate the flow dynamics and study the effect of the immersed capillary for various operating conditions for the CO2 methanation reaction over Ni/Al2O3 catalyst. The results confirmed that the presence of the capillary (diameter 0.5 mm, continuous vs. open-ended) inside the rectangular channel (5 × 40 × 100 mm), the position of the orifice (diameter 0.25 mm), and the suction (2 to 8 ml/min) did not affect the quality of the kinetic data collected. For the current design of the reactor inlet, the flow fully develops within the first 10–25 mm of the reactor domain depending on the total flow rate (100 to 300 mlN/min). Hence, up to 90% of the reactor’s length can be used for in-situ measurements. This work demonstrates that our channel reactor is very suitable for collecting kinetic data, especially for fast and exothermic heterogeneous catalyzed reactions, with a high spatial resolution for gas composition and catalyst surface temperature.

Optimization of the flow distribution in a gyrotron cavity using evolutionary CFD simulations driven by a genetic algorithm

The steadily increasing performance requested to gyrotrons, to comply with their function of heating and current drive in fusion reactors, put a progressively increasing burden on the heat removal from the interaction cavity, where the heat flux can easily reach 20 MW/m2 on its inner surface. The cavity is actively cooled by subcooled water in forced flow in an annular region, and the water flow typically enters and exits through a single inlet and outlet. The high-speed flow entering from the inlet potentially drives an inhomogeneous flow azimuthally in the cavity region, but helps in locally bursting the heat removal due to the impinging effect of the cold-water flow. Here a new design of the water inlet in the cavity region is performed through a simplified genetic algorithm, in such a way that the flow homogeneity in the gyrotron cavity is maximized, without reducing the beneficial cooling due to the impact of the water jet on the cavity wall. The presence of multiple holes feeding the cavity, with their azimuthal location driven by the genetic algorithm, is analyzed through Computational Fluid Dynamics (CFD) simulations. Once the multi-inlet location is optimized, the dimension of the inlet holes is tuned to burst the heat transfer effect, reaching a high level of temperature and flow homogeneity in the cavity.

Electromagnetic field/hypersonic flow field coupled algorithm and its application in the magnetic controlled inlet design

A novel magnetic controlled inlet design method is proposed for the airbreathing hypersonic vehicles cruising at an extremely high Mach number. By introducing the electromagnetic source terms to the Euler equations, an electromagnetic field/hypersonic flow field coupled algorithm is developed as the numerical design tool. A quasi-one-dimensional simplified model of the magnetic controlled inlet is constructed to analyze the compression performance under the different combinations of magnetic field and leading-edge shock angle. The results show that the combination of weak leading-edge shock and strong magnetic field can obtain a better compression effect. Three inlets are designed under the magnetic field with the induction intensity of 0.05 T, 0.08 T, and 0.1 T, respectively. The designed inlets have a contraction ratio of nearly 1.5 and the wall shape is not sensitive to the variation of magnetic induction intensity. With an inflow Mach number of 10, the exit Mach number can be reduced from 5 to 2.5 when the magnetic induction intensity is adjusted from 0.05 T to 0.1 T. In addition, there is no reflected shock in the inner channel of the inlet and therefore the complex shock/boundary layer interaction in the conventional inlet has been greatly relieved. Although the total pressure recovery is significantly reduced, part of the energy loss can be transformed to electric energy by the MHD energy extraction equipment and used to accelerate the nozzle flow.

Effect of gas-induced inlet design on flow pattern and energy loss for small-scale countercurrent vortex reactor: Numerical simulation and experimental investigation

Small-scale vortex reactors have gained attention in the fields of gas-particle multiphase reactions because of the great potential of process intensification. Their performances highly depend upon the vortex flow-induced structure. However, its role has not yet been completely understood. To address the effect of the vortex flow-induced design of a small-scale countercurrent vortex reactor, the gas-induced inlet design with varying aspect ratio (the ratio of inlet height to inlet width of 0.56, 2.25, and 5.06) was designed to numerically and experimentally investigate the flow distribution, energy loss, and process intensification. It was found that for a given flow rate (inlet velocity), and with increasing aspect ratio the maximum tangential velocity is increased whereas the decay of the vortex flow is decreased. The semi-empirical equations were further developed to characterize the spatial distribution of the gas tangential velocity. There is no significant differentiation in axial velocity, but the static pressure near the wall increases significantly. Moreover, the pressure drop of the reactor increases as the inlet aspect ratio increases. Finally, an aspect ratio of 2.25 was found to be optimum for potential multiphase mixing and mass transfer. The results may provide a positive reference for the vortex-flow-based process intensification.

3-D Numerical Study of Effect of Urea Injector Location and Intake Cone Geometry on SCR Performance

In response to current strict laws aiming to reduce motor vehicle emissions, more and more research projects are being carried out in order to enhance the flow of automotive catalysts. There have been substantial efforts to further refine the SCR technology (selective catalytic reduction) for diesel-powered vehicles. Furthermore, only a little distance from the catalytic input between the exhaust system is available for a mobile SCR system. This therefore leads to an insufficient urea residence period, and evaporation and thermolysis at the catalyst entry cannot therefore be completed. This can lead to substantial secondary ammonia and isocyanic acid emissions. Therefore, fast thermolysis, effective ammonia blend with exhaust gas and reduction of ammonia slip are crucial factors for the deployment of SCR technology on cars. The Computational Fluid Dynamics (CFD) approach is used for optimizing the exhaust gas flow inside the existing catalyst by changing intake cone designs which is intended to be used on Euro VI/Bharat Stage-VI emissions legislation compliant heavy-duty diesel engines in India. This study is divided in to two parts. The first part of the study deals with finding the optimized ammonia injector location, and in the second part, the proposed inlet cone design’s flow velocity uniformity index is estimated and compared with that of the existing SCR catalyst model.

Basics, properties, and thermal issues of EV battery and battery thermal management systems: Comprehensive review

This paper presents a comprehensive review on the battery especially Lithium-ion batteries and the battery thermal management systems for electric vehicles. The basics of the battery system and thermal issues related to the battery have been highlighted. Different battery thermal management systems have been discussed in the review. This paper has presented different thermal management systems for electric vehicle battery in details. Air cooling, phase change, and liquid cooling are studied in the reviewed literature, by showing and discussing the results of the previous studies in these fields. Most promising thermal management system is the liquid cooling, because it has the best cooling potential for the EV batteries which gets the researchers attention to improve it based on wide number of increasing studies and developments in the EV liquid cooling systems. Improving the hydraulic and thermal performance of the liquid cold plate which is part of the EV liquid colling systems has not widely been explored in the fields of developing inlets design, outlets, and fins. The review paper could guide the researchers to innovate better liquid cooling systems and improve their cooling and hydraulic performance in battery thermal management systems.

Studi Kinerja Inlet Persegi Panjang sebagai Drainase Jalan

High rainfall condition, especially in tropical countries, often cause flooding or inundation on road section, especially urban road. Puddles that do not enter or are hampered can cause damage to the road. This can be overcome by the inlet design of the road drainage channel that is suitable for the conditions in the field. By paying attention to the distance between inlets, dimensions, and inlet types adjusted to the rainwater discharge and the width of the existing road. Street Inlet is a hole on the sides of the road that serves to accommodate and distribute rainwater runoff along the road leading into the drainage channel.The research was carried out on a prototype that describes the condition of the highway with street inlet modifications such as conditions in the field. The method of analyzing surface runoff in the use of rational methods, inlet dimension analysis is used in the applicable hydraulic rules. The input data used are rainfall data, type of road, type of inlet street, rain runoff or inundation, drainage channel conditions, linear regression. This study discusses the performance of the road inlet to reduce inundation due to rain runoff (with a model of a rectangular inlet on the shoulder of the road). In the research carried out the type of inlet that will be used is the gutter inlet which has a horizontal opening.

Research on flexible skin technique for adaptive bump inlet structure

PurposeAdaptive bump inlet can adaptively change the shape of inlet bump surface according to the flight speed of aircraft, ensuring that the inlet has good inlet-engine match performance in a wide speed range. This paper aims to use a composite flexible skin reinforced by shape memory alloy (SMA) fiber as the deformable structure at bump surface to realize the adjustable bump surface of adaptive bump inlet.Design/methodology/approachAccording to the deformation and load-bearing requirements of adaptive bump, SMA is applied to the design of adaptive bump inlet due to its characteristic of super-elasticity. A kind of SMA fiber is studied. A composite flexible skin reinforced by SMA is proposed, and its mechanical properties are analyzed. On this basis, an adaptive bump inlet is designed in which the composite flexible skin reinforced by SMA is used as bump surface, and the shape of the bump surface is adjusted by way of pressuring. The design scheme and specific parameters of the adaptive bump are given.FindingsAn adaptive bump surface that meets the design requirements of the inlet is designed, which can effectively adjust the inlet throat area with a throat area change rate of 20%.Originality/valueAn adaptive bump inlet with composite flexible skin as a deformable structure at bump surface is designed, and SMA is applied as the reinforcing fiber.

Mixing length correlation for laminar liquid mixing in wall-bounded flows

The aim of this paper is twofold. Firstly, to examine the relationship between mixing length with respect to mixing index for two streams of liquid mixing in a two-dimensional (2D) straight plane channel. Secondly, to propose a new correlation for mixing length for a given mixing index. Although the existing analytical mixing length using LM=1 = PeH could yield accurate prediction, it is, however, restricted to only at a fully mixed condition (i.e., at mixing index M = 1). To accommodate a broad spectrum of mixing indices, a new correlation that would accurately predict the mixing length for a specific mixing index, in the range of 0.5 ≤ M ≤ 1, is proposed. As revealed in this study, this correlation is applicable to the practical range of Péclet number, for 10 ≤ Pe ≤ 1000 and would hold valid, as long as the laminar mixing flow prevails. In addition, the new correlation is applicable to liquid mixing in the mixers with different channel inlet designs (i.e., 2D Y-mixer and 2D T-mixer), and also relevant for three-dimensional (3D) straight mixers with different mixing channel aspect ratios.

Influence of high temperature non-equilibrium effects on Mach 12 scramjet inlet

To better understand the high temperature non-equilibrium effects of a high Mach number (above Mach 8) scramjet inlet, the thermal and chemical non-equilibrium flow of Mach 12 two-dimensional inlet is numerically analyzed by using the thermochemical non-equilibrium gas model including a two-temperature model and air chemical reactions. The thermal equilibrium flow is simulated by using the models of thermally perfect gas and chemical non-equilibrium gas. It is found that the thermal non-equilibrium effects are relatively strong near the cowl shock and in the outer layer of the boundary layer, and gradually weaken in the downstream zone of the cowl shock. The chemical non-equilibrium effects and thermal equilibrium flows mainly exist in the high-temperature region of the boundary layer. Compared with the chemical non-equilibrium gas, the oxygen dissociation reaction near the lower wall for the thermochemical non-equilibrium gas is weaker in the external compression section; It is stronger due to fully excited vibration energy, in the internal compression section. Compared with the other models, the inlet compression ability for the thermochemical non-equilibrium gas is higher, the coefficient of mass flow and total pressure recovery for it are lower. Hence, the high temperature non-equilibrium effects can not be ignored in the design of the high Mach number scramjet inlet.

A numerical analysis of particulate matter control technology integrated with HVAC system inlet design and implications on energy consumption

This paper examines and outlines the development of a novel inlet for an air handling unit (AHU) which controls PM concentration entering mechanically ventilated buildings. The aspiration efficiency reducer (AER), can reduce the ambient PM concentrations drawn into a building ventilation system. The AER device incorporates an array of cylindrical tubed orifices, which create conditions for potential improved indoor air quality (IAQ) and energy savings. Prototypes were designed by reverse-engineering the aspiration efficiency (AE) concept, creating new inlets for AHUs using Computational Fluid Dynamics. This approach helps achieve low AE values and reduce PM concentrations entering the AHU and filter loading rates. 3D k-ω SST models were used to simulate particle laden fluid flow around an AHU with AER attachments. The investigation found that the engineering of wind flow around the AHU and its inlet resulted in lower levels of particles with diameters ≤10 μm entering the AHU. The difference in AE for particles within the PM10 range for the passive AER prototypes in comparison to a commercial rainhood ranged from 5 to 35% for various inlet designs. This translated into increased energy savings of 15.2–20.6% and extended fabric filter lifespan of up to an additional 100 hundred days until saturation. The AER has the potential to reduce energy consumption, minimise waste generation and present cost savings whilst improving IAQ, through a reduction in maintenance activities and the number of filter replacements. This novel technology requires low-capital investment to deliver environmental, energy and economic savings in this sector.

COMPARATIVE PARAMETRIC ANALYSIS OF GAS FLOW IN THREE DIFFERENT DESIGNS OF IN-LINE SCRUBBER BOTTOM INLET

In this study, gas flow fields were simulated using ANSYS 2020R2, Fluid Flow Fluent computational fluids dynamic (CFD) software based on the continuity, velocity, temperature, energy and k - e turbulence. The overall objective of the study is to compare the velocity maps inside the wet scrubber system for three different In-Line scrubber bottom inlet designs. Also, the behavior of the temperature of the mixture inside the scrubber is studied according to the number of nozzles provided by each system from those proposed for study. The numerical simulation using CFD is an effective method to study the flow characteristics of a counter-flow wet scrubber system and the most efficient wet scrubber model is the one with several. The results show that the residuals have a very good job of converging at minimum flow contours and vectors at the inlet across the scrubbing chamber and outlet shows a distributed flow. The speed of water droplets sprayed by the nozzles during mixing with waste gas in the scrubber chamber is double at model with 52 nozzles compared to the first model, equipped with only 13 nozzles. The velocity of clean gases discharged to the ship’s hull shows increases of over 100% of the values, with the increase of the number of nozzles. Spray nozzles improve mixing between the scrubbing liquid and waste gas, by injecting liquid through nozzles to create a fine droplet spray pattern. In this study it can be seen how the number of nozzles influences the quality of the mixture between the scrubbing liquid and waste gas.

First eddy covariance flux measurements of semi-volatile organic compounds with the PTR3-TOF-MS

Abstract. We present first eddy covariance flux measurements with the PTR3-TOF-MS, a novel proton transfer time of flight reaction mass spectrometer. During 3 weeks in spring 2016, the instrument recorded 10 Hz data of biogenic volatile organic compounds above a boreal forest, on top of a measurement tower at the SMEAR (Station for Measuring Ecosystem –Atmosphere Relations) II station in Hyytiälä, Finland. Flux and concentration data of isoprene, monoterpenes, and sesquiterpenes were compared to the literature. Due to the improved instrument sensitivity and a customized wall-less inlet design, we could detect fluxes of semi-volatile and low-volatility organic compounds with less than single-digit picomol per square meter per second (pmolm-2s-1) values for the first time. These compounds include sesquiterpene oxidation products and diterpenes. Daytime diterpene fluxes were in the range of 0.05 to 0.15 pmolm-2s-1, which amounts to about 0.25 % to 0.5 % of the daytime sesquiterpene flux above canopy.

The effect of inlet width on the performance of sediment retention ponds in thermally induced flows

The effects of inlet configurations in sediment retention ponds (SRPs) have been widely investigated by several researchers. However, when considering temperature differentials in the ponds where density and buoyancy change with temperature the challenges associated with the proper inlet design still exist. The buoyancy forces are generated due to the differences in temperature potentially changing the flow in the pond by forming density currents. This study evaluates the effects of different inlet width ratios (IWRs) on the flow pattern and residence time in a sediment retention pond when inflow is colder or hotter than the water in the pond. In this research, an innovative experimental setup was used to create the temperature differentials. The results in the present study show that when the inflow temperature is colder than the water temperature in the pond, increasing the inlet width to the full pond width can effectively increase the pond’s performance. Likewise, when the inflow temperature is hotter than the water temperature in the pond decreasing the inlet width to 30% of the pond width can successfully improve the performance of the pond.

Assessment of Climatic and Anthropogenic Controls on Bridge Deck Drainage and Sediment Removal

Bridge deck drainage is essential to prevent hydroplaning and maintain safety along major roadways. With projected changes in climate, current designs may not be sufficient and a better understanding of the primary controls (climate, bridge deck, and inlet design) on the hydraulic efficiency and sediment removal of drainage systems is needed to maintain public safety. To evaluate the controls on hydraulic drainage efficiency, 576 controlled laboratory experiments were conducted testing grate type (rectangular bar vs. curved vane) and downspout configuration (square vs. circular and 20 cm vs. 25 cm) across a range of flow rates, cross slopes, and longitudinal slopes. An additional 144 sediment erosion experiments were performed to identify controls on the removal of sediment. Hydraulic testing indicated that inflow driven by climate is a primary control on drainage efficiency and spread of water on a roadway. For anthropogenic controls, downspout opening size was found to be the primary control followed by longitudinal slope. Sediment removal results indicated that inflow regime and grate type were the primary controls on the sediment removal rate. Given that inflow, driven by climate, is a control on both hydraulic and sediment removal performance, hydraulic engineers should consider forecasted changes in rainfall intensity in their present-day drainage designs. We provide design guidance and discussion for developing a proactive approach to hydraulic infrastructure in the face of future climate uncertainty.

Analysis on Inlet Nozzle Design Geometry of Tesla Turbine

Tesla turbine is a bladeless turbine that uses a set of discs arranged at a certain distance to rotate and one of the parameters controlling turbine performance is the inlet parameter. The purpose of this study is to optimize the design of the inlet nozzle and analyse its effects on the flow of the fluid. A total of four nozzle designs have been proposed using CATIA while the Solidworks Flow Simulator is used to analyse the fluid flow at various inlet velocities. Then, the most efficient design is then fabricated via 3D printing and put to test by connecting it with the actual Tesla turbine model. Through the results obtained from the analysis, it is observed that Design 4 is the most efficient of all tested nozzles and the highest RPM and output voltage achieved from the nozzle is 7940 RPM and 13.56 V. The difference in velocity and pressure increases as the area of the nozzle outlet reduces, whereas nozzle efficiency decreases as the inlet velocity increases. The result of this study is a source material for increasing the effectiveness of an alternative power turbine in generating electricity by manipulating the inlet design geometry.

Development of an integrated multichannel inlet for improved particle classification in hydrocyclones

The inlet design of hydrocyclones determines the flow field symmetry and facilitates the formation of vortices. In this study, an integrated multichannel inlet based on the Archimedes spiral is developed to improve particle classification by combining the advantages of existing designs. Hydrocyclones with conventional tangent or novel spiral inlets are comparably studied to evaluate the feasibility and superiority of this design using the validated volume of fraction model and two-fluid model. Numerical results show that this novel spiral inlet dramatically improves the flow field symmetry in terms of radial velocity and air core as well as reduces the short-circuit flow and circulation flow. In addition, it also provides strong diversion and pre-separation effects on particles. Consequently, this novel spiral inlet provides superior classification performance than the conventional design, appearing in smaller cut-size, higher cut sharpness, and higher capacity. Such advantages become less evident with increasing channel number, due to the increased turbulence intensity caused by the additional feed streams. The spiral inlet with two channels can largely resemble the design with two tangential inlets in all indices, which makes it the most suitable in this study. This design method can be easily extended to other types of hydrocyclones.

Effect of energy renovation and occupants' activities on airborne particle concentrations in Swedish rental apartments

Exposure to airborne particles causes detrimental health effects, hence their assessment in indoor environments, where people spend most of the time, is important. The influence of energy renovation and occupants' activities on airborne particle concentrations was assessed in seven occupied Swedish residences. Ultrafine particle (UFP, <100 nm) number concentrations, PM2.5 (<2.5 μm) and black carbon (BC, <900 nm) mass concentrations were simultaneously measured inside and outside before, after renovation, and during follow-up.The average indoor UFP number concentrations increased from 6200 (±4070) cm-3 before renovation to 12,700 (±6040) cm-3 during the follow up, as the number of indoor activities doubled. Indoor UFP number concentrations depended mainly on frequency and type of occupants' activities in studied residences (e.g., cooking, candle burning). The average indoor PM2.5 concentration decreased from 8.6 (±5.8) μg m-3 before renovation to 2.5 (±1.3) μg m-3 during follow up, as the activities that generated PM2.5 decreased, and infiltration of outdoor particles could have been decreased due to renovation measures. However, the indication of infiltration decrease during the follow up, assessed on the basis of indoor to outdoor ratios during non-activity times (with no influence of occupants' activities), was not observed after the renovation and should be treated with caution. In this study indoor PM2.5 and BC were influenced by activities and outdoor concentrations. Reduction of exposure to indoor UFP, might be obtained by optimization of kitchen exhaust flows. An improved design of supply air inlets in mechanical exhaust ventilation systems may reduce PM2.5 infiltration.Occupants' logbook records, needed for identification of sources contributing to particle exposure, proved useful but not always accurate compared to technical measurements of activities and UFP concentrations. Development of simple and reliable activity detection systems is needed to complement logbooks and allow accurate assessment of source contribution to particle exposure in homes and associated health effects.

Experimental and numerical investigation on a supersonic inlet with large bleed window

AbstractThe design of a two-dimensional supersonic inlet with large bleed window at low Mach number was developed. Numerical simulation and wind tunnel experiments were carried out to investigate the aerodynamic performance and variable geometric rules of the inlet. The result indicates that the single-degree-of-freedom variable geometry scheme adopted in this paper guarantees the steady work of the inlet over a wide speed range. The large bleed window caused by rotation of the compression ramp appears near the throat at low Mach number. Low-pressure airflow near the bleed window neutralises the original high-pressure airflow behind the shock train, which decreases the overall pressure of the downstream region of the internal contraction section. To match the lower pressure, the structure of the shock train changes from strong $\lambda$-type to weak $\lambda$-type, and finally to a normal shock wave as backpressure increases at Mach number 2.5. Herein, the total pressure recovery coefficient of the inlet near the critical condition improves by 8.5% as the backpressure ratio (Pe/P0) adds from 13 to 14.6 at Mach number 2.5. It proves that the scheme is effective on terminal shock wave control and inlet performance improvement. In addition, due to the background wave and the bleed window, two kinds of shock wave oscillation occur when the backpressure ratio is 13.1.