Experimental Investigation of Performance Characteristics for Savonius-Style VAWTs: A Comparative Study

Savonius-style wind turbines are mainly gauged by two types of coefficients namely: (i) coefficient of power (CP) and (ii) coefficient of torques (CT). Coefficient of power is defined as the ratio of power generated by the turbine to the total power available to the turbine from the free-flowing wind. This is synonymous to the operational efficiency of the wind turbine. Coefficient of torque reflects the torque generating ability of the turbine. In this manuscript, experiments have been performed using three different types of rotor profiles for Savonius-style wind turbines (SSWTs) namely, classical SSWT, Benesh type SSWT and elliptical shaped SSWT using oriented jets. Using deflector plates the orientation of jets have been varied from 20° to 70°. Addition of deflector plates to the wind turbines, assists in maximizing the utilization of wind energy. Experiments have been performed in the laminar air flow. Mechanical loads have been used to study Coefficient of performance (CP) and coefficient of torque (CT) as a function of tip speed ratio (TSRs). The velocity of the wind is adjusted by varying the rheostat that controls the AC motor for the wind tunnel systems. Experimental results indicated that optimum performance could be achieved from all three types of SSWT variants at TSR ∼ 0.70. Out of the three designs studied in this manuscript, elliptic shaped SWT yielded best coefficient of performance equal to 0.39 at TSR = 0.70.

Thermal Analysis of Bajaj Pulsar Disc Brake

The disc brake is a device that used for reducing speed or discontinuing the cycle of the vehicle. many times, using the brake for vehicle starts to heat producing during braking process, such that disc brake undergoes breakage due to high temperature. Disc brake design is done through creo 4.0 and analysis is completed by using ANSYS18.1 workbench. The main purpose of this project is to study the Thermal analysis of the Materials for the Cast Iron, Stainless steel and aluminium alloy at various disc rotor profiles. A comparison between the three materials and profile for the Thermal values at maximum speed of the vehicle.

A new design of the Lobe pump is based on the meshing principle of elliptical gear pairs

The paper presents a new rotor design of an external coupling Lobe pump driven by pair of elliptical gears. The new rotor is a four-tooth elliptical gear with tooth profile is a improve cylocid curve. The improve cylocid curve is the locus of the fixed point on the generation circle, when the circle a pure rolling without slipping on the elliptical centrode of the rotor. The conditions of the rotor addendum and dedendum profiles are also considered. The limited supply angle addendum and dedendum rotor profiles are determined through an iterative algorithm when the generation circle makes a pure rolling without slipping on the ellipse base of the rotor. From there, we proceed to determine the pump design parameters according to the characteristic design parameters forming the rotor profile. The flow rate of the pump is determined by the area of the pockets on a cross-section perpendicular to the pump shaft. On that basis, a Matlab program is written from the mathematical model established by the paper to calculate the rotor design. In addition, the paper also investigates the effect of the coefficient l (semi-major axis divided semi-minor axis of the elliptical centrode ) on the average flow and axis distance. Survey results show that the design at l = 0.5 flow is 52.17% larger and the axis distance is reduced by 21.43% when compared to the traditional design at l = 1. This is the advantage of the new design proposed by this study.

A geometric study of different curves for the rotor profiles of a twin-screw compressor

This paper presents the results of comparisons among some patented solutions for profiling the contours of the rotors in twin-screw compressors. Referring to a base case where all the generating curves are circumferences, patents suggesting to replace arcs of circumference with arcs of conic sections, i.e. parabola, ellipse and hyperbola, but even a straight line segment, are presented and guidelines for rotor profile construction are reported. After setting the size of the compressor, attention is paid to the inter-lobe area, as the sum of the area between two consecutive lobes in the male rotor and of the area of the groove in the female rotor. Actually, this area is strictly related to the volume displacement. Limited to the current case study, the profile including an elliptic segment seems to be the preferable solution for higher inter-lobe area, then for higher displacement, though a number of considerations should be necessary for a broader context.

Inter-lobe clearance estimation for twin-screw rotor pairs with point-meshing features

In practical production, it is impossible even to measure the inter-lobe (meshing) clearance of a screw rotor pair. However, understanding of the clearance distribution is essential since it is a major leakage path which greatly affects the twin-screw pump performance. Previous publications did not disclose explicit detail on how to calculate the meshing clearance for screw rotor pairs with point-meshing features. Therefore, this study proposes a meshing clearance calculation method for screw rotor pairs with point-meshing features. The complex meshing clearance can be simply determined by calculating the shortest distance between two normal-rack profiles generated using point-enveloping principle. Clearance distributions are much more intelligible to be exhibited on a 3-D contact line and the rotor profile. Due to its immeasurability in practice, the adaptability and the solution accuracy of the proposed numerical method are verified by applications on different rotor profiles and comparisons with measured results from a 3-D CAD model. The meshing clearance in a variable-pitch screw rotor pair and the clearance adjustability are also illustrated through the proposed examples.

Study on the reverse design of screw rotor profiles based on a B-spline curve

The female/male screw rotor profile design for a twin screw compressor poses challenges such as frequent parameter modification and a difficult-to-build performance test platform, which affect the efficiency of a rotor profile design. To address these problems, a new idea of applying a B-spline curve to a twin screw compressor rotor profile design is proposed in this article. In addition, the design result underwent fluid simulation based on fluid dynamics technology. This method overcomes the aforementioned challenges. As a meshing line has one-to-one mapping relationship with the rotor profile and reflects important performance parameters of the rotor profile, the method of deducing female and male rotor profiles for a twin screw compressor from a meshing line is proposed. Furthermore, the B-spline curve is used as a composition curve of the meshing line to achieve fast local adjustment of the rotor tooth profile. Based on existing rotor profiles, a meshing line is designed via the B-spline curve, and female and male rotor profiles are derived in reverse. The final rotor profile underwent fluid simulation via computational fluid dynamics analysis under various conditions to analyze the pattern of the internal flow field, which is compared with the results from conventional design.

A Novel Engagement-Pixel Tracking Method for Meshing Clearance Layout of Twin-Screw Rotors

The performance of dry twin-screw compressors is primarily affected by the meshing clearance between a pair of meshing rotors. In this paper, a novel method for meshing clearance layout (MCL) is presented. The presented method is based on the engagement-pixel tracking (EPT) technique, which utilizes discrete-pixel curves generated by the two rotors. An algorithm for the proposed method is put forward. Firstly, when the profile of one rotor is known, the discrete point coordinates of the two rotor profiles and their thermal expansion profiles can be obtained. Secondly, the instantaneous contact models of the two rotors at special meshing positions are acquired under pixel coordinate system. Thirdly, through inspecting the pixels on the profile of a rotor and establishing the corresponding normal vector, the meshing clearance of the two rotors is extracted. Then, the meshing clearances can be generated by extracting the boundary pixels on the other rotor profile. Finally, the meshing clearance layout method is proposed. To verify the effectiveness of the presented method, a case study was conducted on a pair of meshing rotors to extract its meshing clearance. It was shown that the proposed method can be used as a tool for evaluating the clearance distribution of actual machined profiles.

A Novel Rotor Profile Generation Method for Claw-Type Vacuum Pumps Based on Sealing Line

The sealing line between two conjugated rotors is a main leakage path in the vacuum pump, however, it is unable to be adjusted before the rotor profiles are determined in the traditional rotor profile generation method. Therefore, a generation method of rotor profiles for claw-type vacuum pumps based on the sealing line is proposed in this paper. The sealing line can be firstly specified as specific segments regarding the characteristics of claw-shaped rotor profiles. By applying the enveloping theory and the cubic spline curve fitting method, the rotor profile is able to be generated from the sealing line. Moreover, the adjustment method is proposed to segmentally correct the shape of sealing line using the quadratic functions by considering the geometric limitations to avoid interference and undercutting in rotor profiles. A three-lobe claw rotors profile is carried out to demonstrate the reasonability and stability of the proposed method.

Solving the conjugate tooth profile of screw compressor rotors using edge detection method based on Alpha Shape algorithm

While designing a screw compressor, the design of the rotor profiles is the most important because rotor profiles essentially determine the overall performance of the screw compressor. In the field of rotor design, the mutual solution of male and female rotors is characterized by shortcomings such as complex and error-prone calculation, and unsolvable interference. In this study, an edge detection method based on the Alpha Shape algorithm was proposed to avoid the complex calculation process in the traditional planar meshing theory and quickly obtain the point cloud data with singularity points removed. The results show that, with relatively high accuracy and fast processing speed, this algorithm can extract comparatively desirable edges so as to obtain data of the female (male) rotor profile based on the conjugate male (female) rotor profile. The analytical method and the experimental method were used to compare the data of the conjugate rotors, verifying the correctness of the design, which efficiently and highly accurately overcame the problems in mutual solution of male and female rotors. This method can also be applied to design similar conjugate products such as gears, worms, and milling cutters.