Design methodology of a compact size charging system for emergency uses is investigated in this paper. The system consists of a gearing unit, a generator, a charger, and some battery cells. The system’ s electrical model has been introduced and a 3-phase Axial flux surface mounted PM generator with a concentrated winding is picked as a generation unit. The basic equations needed for the generator design are presented as well as the general considerations and constraints for the designs. After validating the design equations using Finite Element Analysis, sizing equations are used to design different machines. The resulted designs are compared based on main characteristics including output power, power delivered to the battery, and generator efficiency. Finally, the performance of the valid designs in the system model is analyzed over a wide speed range. The proposed methodology could be used to design portable power generation units for such applications as rescuing, power system outage, camping, and so on.

Compactness and lightness make high-speed Axial-flux machines eligible for distributed generation application with microturbine. In a high-speed generator driven by micro-turbines, the rotor speed is normally above 30, 000 rpm and may even exceed 100, 000 rpm. The frequency for flux variation is more than 1 kHz. Therefore, designing such a highspeed generator is quite different, in mechanical and electromagnetic respects, from designing conventional generators with low speed and low frequency. Important considerations in designing high-speed Axial-flux generators (HSAFG) for microturbine are discussed in this paper. Results of the efficiency sensitivity versus air gap of the machine are also presented.

In this paper, a novel structure of a Axial flux switching machines for use in wind speed turbines at low speeds has been proposed, which in addition to the previous advantages, has a simple and economical design for the production of this type of machines. In this proposed machine, the magnets are placed on the surface of stator, and the three-phase winding is located in the space between the magnets. After designing according to the criteria like increasing electromotive force, reducing the cogging torque and reducing the total harmonic distortion, using the design of experiments and the surface response method combined with the finite element software, the appropriate dimensions are selected and the machine is optimized. To test the design accuracy, a prototype model is also made.

The objective was to study the effect of change in swirl intensities, S=0. 4, 0. 7 & 1 of the annular swirling flow on the exit flow field of an unconfined annular swirl burner operated at isothermal (only dry air) and reacting flow (premixed methane air mixture) conditions. Reynolds number at the burner’ s annular exit based on its hydraulic diameter (D) was kept constant at 4000. Exit flow field at isothermal conditions was measured using planar particle image Velocimetry rig and processed using commercial software. The percentage decay in the magnitude of peak value of Axial velocity obtained from its radial profile at a height of 4D from the burner exit with the change in swirl intensity of 1, 0. 7, 0. 4 and 0 was 65%, 55%, 47. 2% and 13. 5%. The jet spreading angle was 6. 5o for S=0, 8. 4o for S=0. 4, 9. 8 for S= 0. 7 and 14. 2o for S=1. Recirculation zone was observed only for S=0. 7 and 1. 0. The width of the recirculation zone was 3D (S=0. 7) and 3. 4D (S=1) respectively. The normalized reverse mass flow rates estimated were 0. 027 for S = 0. 7 and 0. 058 for S = 1. 0. The magnitude of turbulence intensities at wake shear layer was much higher than the jet shear layer due to the presence of recirculation zones for S= 0. 7 and 1. 0. The integral length scales calculated were varied in the range of 0. 06D 0. 18D for all swirl intensities. Reaction front was identified by deconvoluting the time mean OH* chemiluminescence using Abel inversion method. The flame became shorter and wider with increase in swirl number which was in consonance with the observation of increase in size of recirculation flow in the isothermal flow. The equivalence ratios at which the lean blow out observed were 0. 58, 0. 6 and 0. 62 for S=0. 4, 0. 7 and 1.

Coreless Axial flux permanent magnet (PM) machines (AFPM) have attracted significant interest over the last decades as an ideal candidate for a wide range of applications. This is generally due to their advantages, such as the high torque density, high power density, and the light weight. This paper investigates the performance of a coreless Axial flux-switching generator (AFSMG) with improved torque characteristics. The inherent feature of the Axial flux-switching machines is the high cogging torque. Hence the main advantage and the novelty of this research is addressing a suitable key for its torque characteristics challenges. In this regard, a comprehensive study is done on rotor tooth shape. First, the geometry and the shape of the rotor tooth are optimized, and then the skewing technique is applied to minimize the cogging torque and improve the total harmonic distortion. Finally, the cogging torque and the THD are calculated in the primary design and the optimal design. The Taguchi method is utilized to improve the primary model. A comparative analysis of the primary and optimized model is carried out, which indicates the better performance of the optimized design. Furthermore, the 3D finite element method is applied to verify the results of the presented model.

This paper proposes a novel Axial flux switching permanent magnet generator for small wind turbine applications. Surface mounted Axial flux switching permanent magnet (SMAFSPM) machine is a new type of these machines that is introduced in this paper. One of the most important challenges in optimal designing of this kind of machines, is ease of construction and maintenance. One of the main features of this machine is putting the magnets on the surface, which makes the construction of the machine easier. The overlapped three-phase winding improves the quality of voltages and power of the machine. To reach the optimum dimensions of machine, centeral composite design (CCD) and response surface methodology (RSM) combined with 3D finite element methods have been used.

Flow control methods have been gradually applied to improve the flow field characteristics of Axial compressors. However, most of the current research is focused on the cascade, and few studies have taken a compressor as the research object. Therefore, a 3. 5-stage transonic Axial compressor is adopted to explore the characteristics of different flow control schemes. The effects of the micro-vortex generator (MVG), segmented boundary layer suction (BLS), and combined technology (COM) on the MVG and BLS are compared by the numerical simulation method. The research results are summarized as follows. The excessive accumulated low-energy fluid in the blade passage induces the occurrence of a corner stall in the last stage stator of an Axial compressor. At this time, the compressor can still work, but the performance has accelerated deterioration. The flow characteristics are effectively improved when the MVG is introduced, the stall margin improvement ΔSM and the peak efficiency improvement Δηe of the last stage are 2. 1% and 1. 02%, respectively. Moreover, the BLS shows advantages in removing the three-dimensional reverse flow and decreasing the total pressure loss compared with the MVG, the ΔSM of the last stage is 2. 69%, and the Δηe is 1. 83%. When the combined technology is applied, it shows a significant advantage in delaying the occurrence of a corner stall, and the stall margin of the last stage is improved by 2. 71%. Based on a quantitative analysis method using loss sources, the three flow control schemes show significant advantages in reducing the secondary flow loss sources and the wake loss sources. Above all, the BLS shows significant advantages in reducing the total pressure loss, and the COM shows an advantage in expanding the stable operating range. The research results will provide a reference for studies of flow control methods related to reducing flow losses and widening stability margins.

Small wind turbines can generate clean energy in diverse locations, from urban centers to rural areas without access to the main grids. This study proposes design optimization of an Axial flux permanent magnet (AFPM) synchronous machine for small scale portable applications. At first, a fast, accurate and pragmatic hybrid analytical model is proposed for performance prediction of the machine. The proposed model is then used as a basis for a direct search optimization process with factual constrains and objective functions to improve the machine in terms of efficiency, weight and to ease the manufacturing process. 3 Dimensional Time Stepping Finite Element Method (3-DTSFEM) is utilized to validate the accuracy and effectiveness of the proposed model and optimization methodology. Output characteristic of the machine from both analytical model and 3-DTSFEM are compared to each other that proves the functionality of the proposed study.

Low swirl combustion is a novel method to stabilize lean premixed flames. In order to utilize this stabilization method in gas turbines, it is required to gain a better understanding of flow and combustion characteristics of low swirl combustion in different working condition. This paper utilizes large eddy simulation (LES) and a thickened flame model to investigate the characteristics of a low swirl flame under two swirl number conditions. Results from simulation of the low swirl flame show that the lifted flame is stabilized above the burner exit by means of a low velocity zone, rather than the presence of a central recirculation zone. With the increase of swirl number from 0.5 to 0.65, the flame and the central recirculation zone move upstream; however, the stabilization mechanism does not change.