Optimized Thermal Efficiency of Rotor and Stator Using CFD

The space between rotor and stator plays a very important role in the design and performance of rotating machinery. The thickness of the gap can vary considerably depending on the size and operating conditions for the different types of rotating machines. Analysis the air velocity and temperature distribution over the air flow gap in stator and motor. Changing the design of rotor to develop turbulence in air flow gap. Compare the velocity and temperature distribution of proposed design with previous studies. The simulation results pinpoint also the periodic heat transfer pattern from the rotor surface and this provides useful information for the prediction of the temperature distribution inside the rotating electrical machine. The simulation results of case-1 show about 117°C temperature inside the rotor machine. Then increase the number of slot inside the rotor machine the total temperature of the rotor machine decreases up to 76°C. Due to low temperature total efficiency of the system increases. And also reduces the loss due to heat. The turbulence effect inside the rotor increase in third case. Due to turbulence effect the air cover large amount of area inside the rotor. So total temperature of the rotor casing decreases. In a system where volume is held constant, there is a direct relationship between Pressure and Temperature. For this case, when the pressure increases then the temperature also increases. When the pressure decreases, then the temperature decreases. So pressure in third case decrease upto1.26Pa and temperature 76 °C.


I. INTRODUCTION
The space between rotor and stator plays a very important role in the design and performance of rotating machinery. The thickness of the gap can vary considerably depending on the size and operating conditions for the different types of rotating machines. For example, with smaller engines, a very small air gap, often less than a millimeter, is maintained to reduce electromagnetic losses and increase efficiency. On the other hand, with larger rotating machines, a very high magnetic field is generated, which can drive the rotor towards the stator with a very high force. Therefore, a wider space is often maintained to avoid contact between the rotor and the stator during engine operation. The machine design process also requires knowledge of the temperature distribution and maximum internal temperature for a given operating condition. The performance and life expectancy of the machine depend on maintaining the temperature during the operation of the machine, in accordance with the instructions and design specifications. Furthermore, the maximum output power is also limited by the increase in temperature in electrical machines [1].

II. LITERATURE REVIEW
Berker Bilgin et al. [1] this review provides a comprehensive overview of the latest analytical models and methods for multidisciplinary design of electric motors for various applications, including power and drive systems for electrified vehicles and thrusters. The article aims to provide designers with examples of electric motors and results on the use of various analysis techniques on electric motors. K. Wang et al. [2] in this article, the Modular Consequent Pole (MCP) rotor is integrated into the Internal Permanent Magnet (IPM) machine with a broken slot to take advantage of the powerful flow focusing effect and reduce leakage flow. Therefore, it is possible to improve the torque density and the utilization ratio of the PM material. Sara Sadr et al. [3]  www.ijoscience.com 30 flows in very tight air spaces in high speed electric cars. For this purpose, the shear stress of the wall on the surface of the rotor, the coefficient of friction of the rotor skin and the losses due to the aging of the wind are numerically evaluated. CFD results are used to closely analyze air flows and we propose a method based on these numerical results that can be used to determine the classic friction coefficient of the rotor skin. The results are compared with the classic correlations.
Jungmayr, G. et al. [4] this article presents magnetic gear motors compared to synchronous permanent magnet machines, which offer higher torque densities. Up to now, the topologies of permanent magnet machines with magnetic teeth examined have been almost exclusively constructions in which the motor and the magnetic gear are arranged coaxially on the same plane. This article presents a new magnetic drive machine, in which the motor and the coaxial magnetic gear are arranged side by side. The concept, the design process, the prototype and the first measurements are presented.

B. Steps of Working
Step 1: Collecting information and data related to Rotating Machines.
Step 2: A fully parametric model of the Rotating Machines for 2 cases.
Step 3: Model obtained in Step 2 is analyzed using ANSYS 18.2.
Step 4: Finally, we compare the results obtained from ANSYS.

C. Finite elements analysis
Finite elements analysis is a branch of fluid mechanics that uses numerical analysis and data structures to solve and analyze problems that involve solid structure. For the present work ANSYS 18.2 software used.

D. ANSYS Capabilities:
In finite element analysis ANSYS software is used that helps engineers for performing the following tasks:  To build computer prototype, components, transfer CAD models of structures in a system products.  Enhances the profile of structural member with shape optimization.  Physical responses, such as stress levels, temperature distributions, or electromagnetic field scan be studied.  To reduce production costs optimization of design is done early in the development process.  Testing of prototypes is done in environments where it otherwise would be undesirable or impossible (for example, biomedical applications).
Graphical user interface (GUI) in ANSYS gives users an easy, interactive approach to documentation, program functions, commands, and reference material. To navigate through the ANSYS program an intuitive menu system is used by users. Input data can be given using a mouse, a keyboard, or a combination of both. www.ijoscience.com 31

E. Steps Of ANSYS Analysis
The different analysis steps involved in ANSYS are mentioned below.

preprocessor
The model setup is basically done in preprocessor. The different steps in pre-processing are  Build the model  Define materials  Generation of element mesh

Building The Model
 Creating a solid model within Catia  First creating air domain according to base paper. The rotor out casing size is 300 mm length and radius and 160 diameter in length.

A. CFD Analysis of Rotor Machine.
The velocity 9.99 and temperature 390k in base paper, due to increasing turbulence effect the velocity inside the rotor decreases and temperature inside the rotor also decrease with velocity. And cooling effect inside the rotor increases.

B. Temperature inside the Rotor Machine
The temperature fig. 29 show the comparative result of base paper result and case 1, 2, 3. www.ijoscience.com 36 The fig. 30 show the comparative result of base paper result and case 1, 2, 3.

D. Pressure inside the Rotor Machine
When the pressure increases then the temperature also increases. When the pressure decreases, then the temperature decreases.

E. Taylor number graph
The fig. 32 show the comparative result of base paper result and case 1, 2, 3.

F. Nusselt number graph
The fig. 33 show the comparative result of base paper result and case 1, 2, 3.  3. The simulation results of case-1 show about 117°C temperature inside the rotor machine. Then increase the number of slot inside the rotor machine the total temperature of the rotor machine decreases up to 76°C.Due to low temperature total efficiency of the system increases. And also reduces the loss due to heat. 4. The turbulence effect inside the rotor increase in third case. Due to turbulence effect the air cover large amount of area inside the rotor.so total temperature of the rotor casing decreases. Pressure and Temperature Relationship. 5. In a system where volume is held constant, there is a direct relationship between Pressure and Temperature. For this case, when the pressure increases then the temperature also increases. When the pressure decreases, then the temperature decreases. So pressure in third case decrease upto1.26 Pa and temperature 76°C.

VII. FUTURE SCOPE
For future study the turbulence effect also improved by using optimization method. The overall design of the rotor optimized by ANSYS design optimization method. The optimization method is very effective and suitable method to improve any design.