Inlet Structure Research Articles

Performance Research and Optimization of Sound Insulation Hood of Air Compressor Unit

The noise control of a compressor has always been a hot spot in the field of industrial application. In this paper, the air inlet structure of the sound insulation hood of an air compressor unit was studied and improved. Acoustic finite element numerical simulation analysis of the sound insulation hood model was carried out using the acoustic software LMS Virtual Lab Acoustics. The simulation results were compared with the experimental data to verify the correctness of the model, and the theoretical results showed a good agreement with the experiment data. The sound insulation performance of the sound insulation hood under different structures was also investigated in this paper. The results show that the main source of unit noise leakage is outward radiation through the air inlet. In addition, the noise at the air inlet of the unit and the overall noise were significantly reduced compared with the traditional sound insulation hood upon installing 120° and 90° diaphragm structures on the inner wall of the air inlet. The optimization results show that the noise reduction effect of the sound insulation hood with a 90° diaphragm structure was better than that with a 120° diaphragm structure.

Influence of the Agitation Pipe on the Flow Field of Electroplating Tank in the Electroplated Diamond Wire Saw

In order to solve the problem of diamonds sedimentation in electroplating tank and uneven distribution of diamonds in coatings, the fluid flow in the electroplating tank formed by three structure kinds of agitation pipe was compared and analysed. Results showed that the middle inlet type agitation pipe can significantly improve the fluid uniformity in the electroplating tank, and setting sand blasting ports at both ends of the agitation pipe can avoid the formation of fluid “dead zone”. Along the direction of the agitation pipe, the middle inlet type agitation pipe improves the overall flow of the fluid. In the position of the wire saw passing through, the difference of the speed in the electroplating tank of the middle inlet type is 47.17% and 15.25%, which is significantly lower than that of the water inlet structure of one end by 134.48%. As a result, it can significantly improve the plating effect of the wire saw.

A direct numerical simulation study of skewed three-dimensional spatially evolving compressible mixing layer

The turbulent flow of spatially developing and high-speed hydrogen/air mixing layers subject to small skew angle ζ is systematically investigated by means of direct numerical simulation. The present database features both detailed chemistry and detailed transport (i.e., Soret, Dufour, and bulk viscosity effects). The angle ζ measures the misalignment of the two asymptotic streams of fluid, whose interaction creates the turbulent mixing region. Numerical simulations have been carried out either in the absence of skewing, namely, perfectly parallel streams (ζ=0°), or in skew angles ζ=5°, 10°, and 15°. The streamwise evolution and the self-similar state of turbulence statistics of skewed cases are reported and compared to the unskewed and reference case. The present computations indicate that the transitional region and the fully developed turbulence region depends strongly on the degree of flow skewing at the inlet. In particular, we find that skewing yields faster growth of the inlet structures, thus leading to mixing enhancement. The underlying mechanisms responsible for turbulence modulation are analyzed through the transport equation of the Reynolds stresses. One possible perspective of the present work concerns the mixing control and a reliable comparison between the experiment, simulations, and turbulence modeling.

P27.07 Pancoast Tumour Presenting as Lower Limb Weakness; Would You Recognise It?

Pancoast tumours were an obscure entity until Henry Pancoast first described them in the 20th century. This tumour typically involves the apical chest wall and thoracic inlet structures. To characterise a lesion as a Pancoast tumour, it must arise from the lung apices and cause neurological dysfunction. It may present as pain in the shoulder girdle and arm (along C8, T1 and T2 dermatomes), weak or atrophied hand muscles and Horner's syndrome, a constellation of symptoms collectively known as Pancoast Syndrome. These tumours that form 5 per cent of all the NSCLC (Non-small cell lung carcinoma) are often not detected early and have a high predilection for metastasis leading to an overall poor prognosis. The following clinical case study accurately describes a Pancoast tumour's signs and symptoms and emphasises the need for its early recognition by retaining a high index of suspicion even in the most routine of circumstances. A 56-year-old man presented to the emergency department with sudden onset of left leg weakness associated with mild sensory loss. Further questioning revealed clumsiness of the left hand. The initial impression was that of a stroke, but the CT head was found to be unremarkable. It was only later that examination revealed a classical Horner's syndrome; miosis, partial ptosis and hemifacial anhidrosis, raising suspicion of an apical pathology. The chest radiograph was deemed normal, and hence a CT scan of the chest was requested, which showed a left-sided Pancoast tumour. A Subsequent MRI revealed cord compression at T2-T3 levels with tumour infiltration into the left brachial plexus. CT guided biopsy confirmed lung adenocarcinoma with distant spread. He underwent five cycles of radiotherapy, during which he developed neuropathic pain, particularly along the left shoulder and upper chest. His left-sided Horner's syndrome improved clinically. The left fingers' clumsiness did not worsen, and he continued to use his left hand despite some residual weakness but permanently lost bilateral leg function due to spinal cord metastasis. This case demonstrates the significance of a thorough medical history (including smoking) and examination while assessing patients with seemingly unrelated symptoms. The presence of "normal" physical and imaging studies should provoke the clinician to think of an alternative possibility. The inability to include Pancoast tumour in the differential diagnosis most commonly causes a delay in diagnosis and management. Early recognition is the key since the prognosis is directly dependent on timely treatment, which affects patients' survival rate with lung adenocarcinoma.

Technical assessment of installed domestic biogas plants in Kavre, Nepal

Domestic biogas technology is a promising source of renewable energy for cooking in developing countries. It is popular in Nepal's rural and peri-urban areas and can be scaled-up to replace solid fuel cookstoves. This study focused on the technical assessment of installed biogas plants such as structural components, pipelines and valves, stove and burner, biogas production and utilization, and effluent disposal system in 303 homes in Kavre district, Nepal. Furthermore, it evaluated the feedstock material's physical and chemical parameters to ascertain their implications on biogas production. The plants' problems were mainly due to faulty components and lack of proper operation and maintenance. About 18% of plants were nonfunctional, out of which 9% of the plants were damaged due to the 2015 mega-earthquake. The highest number of damages was found in the mixture of the inlet structure. About 55% of mixtures were nonfunctional. Almost 77% of users used cow dung and toilet waste either individually or in combination with animal urine as feedstock materials in the digester. The Carbon: Nitrogen (C: N) ratio of feedstock materials ranged from 5:1–24:1, with only 4% of samples measuring C: N greater than 20:1. Similarly, pH (7.7) levels were on the higher side.

Hydraulic Performance of Water Inlet Device in Ship Scoop Cooling System

The scoop cooling system is widely used in advanced ships which usually requires a water inlet device protruding out of the board. The structure of the water inlet device not only determines the cooling water flow into the system, but also affects the additional resistance of the hull. The ratio of the static pressure difference between windward side of the device and the environment and the dynamic pressure head of the cooling water entering the flow channel is defined as the scoop lift head. The scoop lift head and additional resistance are used to describe the hydraulic performance of the water inlet device of the scoop cooling system, and a theoretical analysis method for the performance of the water inlet device of the scoop cooling system is proposed. The actual ship parameters are used to verify the scoop cooling capability and drag resistance characteristics of the water inlet device.

Improved Design and Dynamics Characteristics Research of a Composite Percussion Drilling Tool

Abstract Internal motion and dynamics mechanism studies of a new composite percussion drilling tool aim at reducing stick-slip phenomenon and improving rock breaking efficiency. In this study, experiments are performed using composite percussion drilling tools to investigate its torsional and axial composite impact performance. According to the experimental results, a six degrees-of-freedom (6DOF) rigid body motion model was established to study the passive motion of a torsional hammer. The obtained results, including the tangential acceleration, were verified with experimental data, and the small pressure differences between the high and low pressure areas, which mainly determined by the inlet structure, is the main reason for the poor torsional impact effects. Based on these discoveries, the improved design increases the inlet flow to 17.2% of the total, the pressure differences to 0.05 MPa, and the instantaneous tangential acceleration to 0.198 m/s2, which results in increased tangential acceleration fluctuation amplitude by 1137.5% and greatly improved torsional impact performance. This research can provide a baseline for stick-slip reduction technology optimization.

Design and analysis of a supersonic axisymmetric inlet based on controllable bleed slots

Aiming at the problem of starting and inlet-engine matching of axisymmetric variable geometry inlet with complex structure, a novel design concept of axisymmetric inlet is proposed based on controllable bleed slots switch. The laws of the typical geometric parameters of multi-slots effecting on inlet start, supercritical and subcritical performances are numerically studied. Accordingly, a three-dimensional aerodynamic design scheme of the inlet operating at Ma1.5-4 and control laws of the bleed slots are gained, which is slightly altered inlet surface and structure is simplified. The aims of minimum starting Mach number to 2 and inlet-engine matching inlet are achieved by controlling switch of bleeding slots, and inlet operates well at high total pressure recovery and low exit Mach number. The results show that: at Ma=2, the inlet starts with 30% bleeding and 16.5% total pressure recovery coefficient improving; At Ma=3, mass flow of inlet-engine matches with 23% subsonic bleeding but cost of total pressure loss about 2.6%.

Experimental Study of Flow Characteristics in Vortex Drop Shaft

AbstractVortex drop shafts are utilized to dissipate and transport the energy of flows in sewerage networks. A vortex drop shaft is composed of three parts: the inlet structure, the vertical shaft,...

Simulation analysis on the separation performance of spiral inlet hydrocyclone

ABSTRACT The misplacement of coarse particles in overflow and fine particles in underflow are common problems in hydrocyclone separation. This study aimed to propose a hydrocyclone with a spiral inlet structure to improve the separation performance, and the design method of the spiral inlet is given. Based on verifying the accuracy of the VOF model and the Mixture model, the flow field characteristics and separation performance of the traditional tangential inlet hydrocyclone and the spiral inlet hydrocyclone were compared by numerical simulation method. The results showed that the spiral inlet hydrocyclone had a higher tangential speed and centrifugal strength than that of the traditional hydrocyclone. Moreover, the spiral inlet hydrocyclone had a lower turbulent kinetic energy and more stable flow field compared with the traditional tangential inlet hydrocyclone. The separation accuracy of the spiral inlet hydrocyclone is 12.24% higher than that of the tangential inlet hydrocyclone.

Numerical study on the flow characteristics of slot cooling header after rolling

In order to study the flow distribution characteristics of the slot cooling header after hot rolling, and the influence of different structure and technological parameters on the flow uniformity of outlet velocity and length direction was obtained. The three-dimensional steady-state numerical simulation analysis of the flow inside the manifold was carried out by FLUENT analysis software. The influences of inlet pressure, shape and structure of intermediate transition cavity were studied respectively. The results show that within the range of 0.1~ 0.5MPa of the inlet pressure, the velocity fluctuation in the direction of the outlet length increases with the increase of the pressure, and the width decreases from the middle of the gap to both sides. The flow velocity at the jet outlet can be increased by changing the angle of outflow tilt of the water supply pipe.

Experimental Study on the Inlet Discharge Capacity under Different Clogging Conditions

Storm drainage inlets transport urban runoff and discharge to underground sewer systems. If the inlet structure is blocked, the urban drainage system is hampered, leading to urban flooding. To quantitatively analyze the influence of clogging conditions on inlet discharge capacity, laboratory experiments were conducted to address the impact of different inlet clogging conditions on inlet discharge capacity under different upstream discharge conditions. These were based on a two-layer platform that mimicked a complete inlet structure including a drainage grate, a rainwater well, and a connecting pipe. The results show that the water flow near the inlet was similar to weir flow when the rainwater well was not full, whereas the water flow state near the inlet behaved similarly to orifice flow after becoming full. In addition, it was found that the clogging extent and position can significantly influence the comprehensive discharge capacity of the street inlet. The experimental dataset was used to calculate the inlet discharge coefficients of the weir and orifice flow states under different clogging conditions. The results are applicable to research addressing the formation mechanisms of urban floods. Additionally, this study is of practical significance for early warning systems and emergency response support during heavy rainfall.

Inflow characteristics for generating axis-switching phenomenon of heated rectangular jets

Flow characteristics due to the axis-switching phenomenon are numerically investigated for heated rectangular jets with typical inlet conditions and three aspect ratios (AR), namely 1.0, 1.5, and 2.0. To examine various inlets and their relation to the axis-switching flow, an inflow generator is newly devised, wherein jet flows from an orifice plate and a long pipe nozzle can be realized. Depending on the inlet conditions, the 45° and 90° axis-switching phenomena for the rectangular jet are observed to appear differently. As the aspect ratio increases and jet temperature decreases, the axis-switching positions are delayed downstream. It is observed that the strong and weak states of the axis-switching flows can be interpreted by the crossover locations of the jet half-widths and the saddle-shaped velocity profile is not the only main factor for axis-switching flow. As the jet temperature increases, a well-mixed state is quickly obtained, and the mixing performance of the square jet is better than that of the rectangular jet. For both isothermal and heated jets, the flow mixing is improved by the axis-switching flow. Various analyses are attempted to find the specific inlet structure for the axis-switching flow. From the results, the special features for inflow criterion producing axis-switching flow can be explained by factors such as the deformation parameter, interrelations between shear strain and normal rates, turbulence-driven and geometry-driven streamwise vortices, and normal Reynolds stresses.

Experimental study of droplet behavior in a swirl flow field induced by two kinds of guiding vanes and inlet structure optimization

Droplet breakage is a common phenomenon in converting a pipe flow to a swirl flow in a vane-type pipe separator (VTPS)’ inlet. The evaluation of the dispersed droplet sizes after breakage is crucial to the optimum design of the inlet structure and the estimation of the oil-water separation performance. This paper studies the droplet behavior in a swirl flow produced by guiding vanes. Experiments are performed with two different guiding vanes at the inlet of the VTPS. The sizes of the produced oil droplets at the downstream of the guiding vanes are measured in situ using a Malvern Insitec SX. The results indicate that the streamlined deflector is superior to the semi-elliptical plate for the VTPS’ optimization based on the comparison of the droplet sizes in their respective induced swirl flow fields, which can be explained by a modified T-model. Our study suggests that the use of the modified T-model is a reliable method to optimize the design of the guiding vane in the swirling generating stage.

Research on inlet structure optimisation and numerical simulation of three-phase separator

Three-phase separators are increasingly used in fields such as the pretreatment of oilfield produced fluids and the treatment of oily sewage in the chemical production process. As the core component of the three-phase separator, the inlet structure can make the relatively stable flow field obtained by the separator provide strong guarantee for subsequent separation. An advanced design of inlet structure can improve the separation effect of the separator to a certain extent. In this paper, the Fluent software was used to numerically simulate the inlet structure of the three-phase separator. Through the analysis of different types of inlet structures, the general rules were summarised. Finally, combined with related research results, a bottom cylindrical inlet structure was developed and designed to improve the rectification performance of the inlet structure and effectively prevent the blocking of the distribution cylinder from occurring.

Treatment of Storm Water from Agricultural Catchment in Pilot Scale Constructed Wetland

Abstract Constructed wetlands as a treatment system are widely explored in different climate conditions and established to be effective in pollution removal from water environment. This study aims to demonstrate the performance of pilot-scale subsurface flow constructed wetland for storm water treatment in Latvia. The catchment basin was located in a farmyard of agricultural area and storm water was collected from the impermeable pavements. Storm water was accumulated in an open pond and periodically pumped above the filter part of the subsurface flow constructed wetland. Grab samples were collected once or twice per month at the inlet and outlet of the treatment system during a period of 73 months from year 2014 to 2020. Water quality parameters as nitrate nitrogen (NO3-N), ammonium nitrogen (NH4–N), total nitrogen (TN), orthophosphate phosphorus (PO4-P), and total phosphorus (TP), total suspended solids (TSS), biochemical oxygen demand (BOD5) and chemical oxygen demand (COD) were monitored. Water level at the inlet structure was automatically measured and flow rate was calculated based on the Manning equation for partially filled circular pipes. Results showed the reduction of average concentrations for all parameters during the study period. However, in some sampling cases concentrations increased at the outlet of the treatment system and can be explained by influencing factors of farming and maintenance. The treatment efficiency of NO3-N, NH4-N, TN, PO4-P, TP, TSS, BOD5 and COD concentrations was 17 %, 68 %, 55 %, 78 %, 80 %, 57 %, 80 % and 74 %, respectively. The study site demonstrated a potential to improve water quality in the long term.

Structural parameters optimization of submerged inlet using least squares support vector machines and improved genetic algorithm-particle swarm optimization approach

It is important to optimize the structure of inlet due to the increasing demand of ram air. In this paper, structural optimization of the submerged inlet is pursued using a hybrid model by integrating least squares support vector machines (LS-SVM) prediction model and improved genetic algorithm-particle swarm optimization (GA-PSO). Inlet shape is controlled by changing three-dimensional geometric parameters. Ramp angle, width to depth ratio and ramp length play significant parts in this optimization process. Ram efficiency and mass flow are the main objectives of the performance evaluation. Results show that the prediction error of the mass flow and ram efficiency is 2.31% and 0.54%, respectively. Comparison with the original geometry is used to prove the optimization capabilities of the proposed optimization method. The mass flow and ram efficiency are increased by 29.2% and 10.0%, respectively. In addition, the characteristics of the optimized submerged inlet geometry are numerically investigated. The numerical results are compared to the optimization results and indicate that this optimization method has high validity. The error of ram efficiency and mass flow is 0.30% and 0.66%, respectively. Consequently, this optimization method can be valuable to aircraft engineers-by providing a novel approach for the design of the submerged inlet.

Preliminary preparation of water supply system for the headbox through Pulsar water treatment plant

Today, the main quality criterion in the production of fiberboards is a uniform supply of mixed wood fiber slurry to the mesh part of the press using a high pressure headbox. The interaction of water, various inclusions of waste water, wood-fiber semi-finished product, as well as stainless steel provokes occurrence of chemical reactions that cause intense corrosive destruction of working parts of the inlet. At present, the study of corrosion of the inlet structure pursues the goal of determining characteristic factors caused by the aggressive environment arising at the time of mixing the wood-fiber suspension with the water flow. The analysis of fiberboard production by the wet method examines the possibility of introducing equipment designed for high-quality water treatment with the possibility of cleaning it from various impurities. Pulsar water treatment system is designed for oxidation of soluble metals with their conversion into filterable forms, cleaning from organic and inorganic contaminants due to filters of soft and coarse cleaning using AS sorbents. The station operates autonomously with control of the output gravity for up to 10 years with annual losses of no more than 10% of filter elements.

Influence of inlet structures of planetary reactor on gas reaction path in AlN-MOVPE process

Numerical study on the influence of inlet structure of planetary reactor on gas reaction path and growth rate in AlN-MOVPE was investigated. It was found that, for the conventional two-inlet reactor (base reactor), the reaction is dominated by the adduct reaction path, and the growth rate is low but evenly distributed; for the inverted inlet reactor, i.e., group-III in lower inlet and group-V in upper inlet, the reaction is dominated by the pyrolysis path, and the growth rate is higher than the base reactor but the growth uniformity is decreased. By moving the position of the inlet separator closer to the ceiling for the inverted inlet, the growth uniformity is improved. When the number of reactor inlets increases from two inlets (base reactor) to three and five inlets, the growth rate increases, the growth uniformity improves, and the reaction changes from the adduct-dominated path to the pyrolysis and adduct coexisted path. Besides varying the inlet geometry, we also found that decreasing the NH3 flow rate will enhance the pyrolysis path and the growth rate for the above reactors.

Study on Effects of Inlet Resistance on the Efficiency of Scroll Expander in Micro-Compressed Air Energy Storage System

As an important part of a micro-compressed air energy storage system, the scroll expander directly affects the efficiency of the whole energy storage system. The effects of resistance on the efficiency of scroll expander caused by inlet structure and size are discussed with theory analysis and experimental methods in this paper. Micro-compressed air energy storage system has aroused widespread attention because of its pollution-free, high flexibility, in the community, remote areas power supply. Comprehensive experimental work with the selections of different size and structure of the air inlet of the scroll expander was performed with the cutting angle of air inlet chamber of the scroll expander. The results of the experiments are discussed on how exergy efficiency and inlet flow of the scroll expander were affected resulting from the cutting angles dissected. The results show that a maximum value exists for exergy efficiency of the scroll expander. Therefore, the exergy efficiency of the scroll expander can be effectively improved by enlarging the air inlet port dimension and modifying the size of air chamber.