spiral groove
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Flow field of shroud leakage flow for a single-stage axial turbine has been investigated in this article. The spiral groove seal (SGS) is adopted for shrouded rotor blade to reduce tip leakage and improve turbine aerodynamic performance. A series of three-dimensional (3D) computational fluid dynamics (CFD) simulations are performed to investigate leakage characteristics and flow mechanism of various configurations with different angle, depth, width, and grooves number of the SGS. The original staggered labyrinth seal (LS) is also calculated for comparison. The results illustrate that small spiral groove angle can create more axial flow resistance; meanwhile, it will increase grooves number existing in the axial direction. Groove depth and tooth width will influence the number, shape, and strength of vortex in the groove. The leakage mass flow can be reduced by 36% and isentropic efficiency of the turbine can be increased by 0.26% when spiral groove angle, depth, and width of the SGS are 1.5°, 1.8 mm, and 0.8 mm, respectively. Overall, the optimal SGS can influence vortex generation and enhance energy dissipation in shroud cavity to reduce the leakage and suppress mixing loss of leakage flow with the main flow to some extent. It can be attributed to the combination of throttling effect and pumping effect of the SGS that realize leakage reduction and efficiency improvement. As a result, the SGS can effectively improve tip leakage flow of shrouded blade in axial turbine.

Purpose The purpose of this paper is to investigate the influence rule and mechanism of three degrees of freedom film thickness disturbance on the transient performance of spiral groove, upstream pumping spiral groove dry gas seal (UP-SDGS) and double-row spiral groove dry gas seal (DR-SDGS). Design/methodology/approach The transient performance of spiral groove, UP-SDGS and DR-SDGS are obtained by solving the transient Reynolds equation under different axial and angular disturbance coefficients. The transient and steady performance of the above-mentioned DGSs are compared and analyzed. Findings The film thickness disturbance has a remarkable impact on the sealing performance of DGS with different structures and the calculation deviations of the leakage rate of the UP-DGS will increase significantly if the film thickness disturbance is ignored. The axial and angular disturbance jointly affect the film thickness distribution of DGS, but there is no significant interaction between them on the transient sealing performance. Originality/value The influence mechanism of axial disturbance and angular disturbance on the transient performance of typical SDGSs behavior has been explained by theory. Considering small and large disturbance, the interaction between axial disturbance and angular disturbance on the transient performance have been studied.

Abstract The high requirements for sealing performance in high-speed rotating machinery has led to the design of floating seal with annular spiral groove that offer the advantages of low leakage and extended stability. However, efforts to model the dynamic performance of these floating seal have suffered from the great complexity of the flow field. The present work addresses this issue by establishing a transient Reynolds formulation of a floating seal with annular spiral groove in a rotating coordinate system based on the small perturbation method. In addition, the influence of radial eccentricity and film thickness on the solution divergence and calculation accuracy is calculated. The dynamic stiffness and dynamic damping matrixes are built. Then the variation rules of the dynamic stiffness and damping coefficient of the gas film with structure and working conditions are investigated in detail. The results show that the floating ring seal is more suitable for the service conditions of small film thickness, low pressure, high speed and large eccentricity. Accordingly, the results obtained lay a theoretical foundation for evaluating real-world applications of floating ring seal.

This study aims to determine the dimensions of the spiral groove condenser to convert plastic waste into fuel and determine the material's effectiveness for making spiral groove condensers. This research was conducted in stages: potential identification, data collection, equipment design and calculation, design validation, testing, and equipment feasibility test. In the testing and equipment feasibility test, namely by inserting plastic waste into the pyrolysis process reactor, then heated to a temperature of 180 oC and an evaporation process occurs, the vapors obtained are then condensed to be fuel. The spiral groove condenser design is made with a length of 3 m, a diameter of 30 cm, and a height of 34 cm use ½ inch galvanized iron material and a plate thickness of 0.0127 mm. The cooling water circulation process uses a spiral iron pipe, with a temperature of steam entering the condenser 180 oC and the temperature of the water in the condenser is 40 oC. From 1000 gr of plastic waste can be produced as much as 100 ml of fuel.ABSTRAKPenelitian ini bertujuan untuk mengetahui dimensi kondensor alur spiral untuk merubah sampah plastik menjadi bahan bakar minyak, untuk mengetahui efektifitas bahan pembuatan kondensor alur spiral. Penelitian ini dilakukan dengan tahapan : identifikasi potensi, pengumpulan data, desain peralatan dan perhitungan, validasi desain, pengujian dan uji kelayakan alat. Pada proses pengujian dan uji kelayakan alat yaitu dengan memasukkan sampah plastik kedalam reaktor proses pirolisis, selanjutnya dipanaskan sampai temperatur 180 oC dan terjadi proses penguapan, uap yang yang diperoleh selanjutnya di kondensasi menjadi bahan bakar minyak. Rancangan kondensor alur spiral yang telah dibuat dengan panjang 3 m, berdiameter 30 cm dan tinggi 34 cm menggunakan bahan besi galfanis ½ inch dan tebal plat 0.0127 mm, proses sirkulasi air pendingin menggunakan pipa besi spiral, dengan suhu uap yang masuk ke dalam kondensor 180 oC dan temperatur air pada kondensor 40 oC. dari 1000 gr sampah plastik dapat dihasilkan sebanyak 100 ml bahan bakar minyak.

In order to meet the requirements of rice field precision direct seeding in rows and hills, a spiral grooved seed metering device for rice field precision direct seeding in hills is designed. The Matlab software is used to study the movement trajectory of rice buds in the spiral groove during the seeding process. Based on the quadratic regression-orthogonal rotation combination design, and taking the working speed of the seeding wheel, the spiral groove length and the helix angle of the spiral groove as the test factors, as well as the qualified rate of hill diameters, the qualified rate of hill grains and the miss-seeding rate as the indicators, the seed metering performance is tested by JPS-12 metering device test bench. The test data are analyzed by using Design-Expert 6.0.10 software to obtain a mathematical model between the factors and indicators. The test results show that when the spiral groove rise angle is 71.0°, the spiral groove length is 10.8mm, and the working speed of the metering wheel is 23.2r/min, the qualified rate of hill diameter, qualified rate of hill grains and miss-seeding rate are 91.06%, 94.64% and 3.64% respectively. The seeding performance meets the agronomic requirements of rice field seeding.

Purpose The purpose of this paper is to investigate the dynamic characteristics of spiral groove liquid film seal under the effect of thermal–fluid–solid coupling. Design/methodology/approach The dynamic analysis model of spiral groove liquid film seal under the effect of thermal–fluid–solid coupling was established by perturbation method. The steady-state and perturbation Reynolds equations were solved, and the steady-state sealing performance and dynamic characteristic coefficients of the liquid film were obtained. Findings Compared with the liquid film without coupling method, a divergent seal gap is formed between the seal rings under the effect of thermal–fluid–solid coupling, the minimum liquid film thickness decreases, the dynamic stiffness and damping coefficients of the liquid film are increased and the thermoelastic deformation of the end-face improves the dynamic performance of the liquid film seal. Originality/value The dynamic characteristics of the spiral groove liquid film seal under the effect of thermal–fluid–solid coupling are studied, which provides a theoretical reference for optimizing the dynamic performance of the non-contacting liquid film seal.

Abstract Due to its good cutting performance in titanium alloy machining, integral end mills are more and more used in machining aero-engine impeller blades. The tool spiral groove plays the role of chip acceptor and chip removal, and the accuracy of its parameters has an important effect on the cutting performance. In the grinding process of the spiral groove, the grinding wheel's external grinding is mainly involved in the grinding task. The grinding wheel's wear degree is related to the grinding time and grinding times of the grinding wheel, and the wear of the grinding wheel will lead to the change of the parameters of the spiral groove. To achieve the accurate solution of the grinding wheel surface wear profile, image processing technology was used to extract the spiral groove end section contour coordinates of the grinding wheel and fit them. The worn sand profile was solved based on the contact line principle, and the grinding wheel wear amount was obtained. The traditional reconstruction method was used to verify the algorithm. The results show that the accuracy of the reverse algorithm for the wear profile of the grinding wheel is relatively high.

Although a two-dimensional (2D) valve has excellent performance, the processing of its spiral groove has a high cost and is time-consuming. This paper proposes a novel torque motor based on an annulus air gap (TMAAG) to replace the negative feedback function of the spiral groove to reduce the machining difficulty. In order to study the torque change law of the TMAAG, the air gap permeance was analyzed, and then a qualitative analytical model was established. Orthogonal tests were carried out to initially select the crucial parameters, which were further optimized through a back propagation (BP) neural network and genetic algorithm. The prototype of TMAAG was machined, and a special experimental platform was built, and experiment results are similar to the simulation values, which verifies the accuracy of the air gap analysis and qualitative model. For torque-angle characteristics, the output torque increases with both current and rotation angle and reaches about 0.754 N·m with 2 A and 1.5°. While for torque-displacement characteristics, due to the negative feedback mechanism, the output torque decreases with increasing armature displacement, which is about 0.084 N·m with 2 A and 1 mm. The research validates the unique negative feedback mechanism of the TMAAG and indicates that it can be potentially used as an electro-mechanical converter of a 2D valve.