Natural Frequency and Resonance Study of FGM Turbo-Machinery Blade Using Campbell Diagram

Turbo machinery rotating blades are a vital component of aero-engines for transferring the energy of gas flow to kinetic energy. Rotating turbo-machinery blades are prone to fail under working fields with high temperature, high speed, high pressure and resonance of blades with prime engine. Vibration of the turbo-machinery blades need to be studied carefully for safe and reliable operation of the engine. Thermal barrier coatings (TBC) layers are used to protect the blade metal at higher operating temperature though these can be plagued due to phase instability, thermal instability and adherence problems. TBCs also tend to spall due to thermal expansion mismatch with the super alloy substrate or because of erosion/impact caused by particles in the high-velocity combustion gases. Functionally graded materials (FGMs) are a relatively new class of materials that can solve these problems in high-temperature environments and can be considered as potential material for making gas turbine blades. Unlike composite materials the functionally graded materials (FGMs) are free from delamination and debonding and have the ability to withstand high temperature without TBC coatings. In this present study natural frequency of the FGM turbine blade for various rotational speeds during actual operation is determined using finite element technique. As the aero-engine is complex in nature therefore harmonic resonance can always occur in the aero-engine system and it is difficult to determine the natural frequency at varying speed during actual operation. The chances of failure of the blade also increase because of harmonic resonance. Hence, the resonance property is required to investigate of the FGM blade in details. Various rotational speed and operating temperature is considered to determine the natural frequencies of the blade. The resonance studies for each case are performed using the Campbell diagram. Resonance margin is calculated for each case and safe operating speed is determined. This study could serve as ready reference for safe operation of turbo-machinery engine considering FGM blade for specific range of engine speed.

A Study on Low Velocity Impact Behaviour of Functionally Graded Sandwich Conical Shell Under Thermal Environment

Turbo machinery rotating blades are a vital component of aero-engines for transferring the energy of gas flow to kinetic energy. Rotating turbo-machinery blades are prone to fail under working field with high temperature, high speed, high pressure and impact of blades. Recently Functionally graded materials (FGMs) are used in turbo-machinery blades due to its advantage of delamination and debonding free structure and ability to withstand high temperature during operation. As these aero-engine blade works in high temperature condition therefore use of ceramic FGM in the outer surface of the blades gives potential advantage. However, low velocity impact is a potential hazard of the blade due to rigid structure of the blade while considerable thickness of ceramic present in the outer surface of the blade. The chances of impact failure of the blade also increase in that case. Hence, low velocity impact of the turbo-machinery blades need to study carefully for safe and reliable operation of the engine. In this present work the low velocity impact characteristics of the FGM sandwich turbine blade under various operating temperature are determined using finite element technique. The low velocity impact performances are evaluated in terms of time histories of the contact force, velocity of the projectile, shell deflection and indentation considering various impactor initial velocities, core to FGM thickness ratio (hcore/hfgm) and blade operating temperature. The upper and lower surfaces of the functionally graded structure reinforced by ductile pure metal layers appear to play a significant role in protecting the structure’s functional integrity from damage.

Application of Gas Foil Bearings in China

Gas foil bearing has been widely used in high-speed turbo machinery due to its oil-free, wide temperature range, low cost, high adaptability, high stability and environmental friendliness. In this paper, state-of-the-art investigations of gas foil bearings are reviewed, mainly on the development of the high-speed turbo machinery in China. After decades of development, progress has been achieved in the field of gas foil bearing in China. Small-scale applications of gas foil bearing have been realized in a variety of high-speed turbo machinery. The prospects and markets of high-speed turbo machinery are very broad. Various high-speed turbomachines with gas foil bearings have been developed. Due to the different application occasions, higher reliability requirements are imposed on the foil bearing technology. Therefore, its design principle, theory, and manufacturing technology should be adaptive to new application occasions before mass production. Thus, there are still a number of inherent challenges that must be addressed, for example, thermal management, rotor-dynamic stability and wear-resistant coatings.

Computational tool for teaching learning velocity triangle of hydraulic turbines

This paper presents an investigation about utilizing computational tools applied to specific issues of the Turbo machinery. This subject is concentrated by third-year understudies in B.S. Mechanical Engineering Program. These understudies have previously learned the Fluid mechanics, which is required in structuring distinctive machine components. While teaching Turbo machinery, understudies frequently become overpowered by an incredible number of hypothetical ideas, loads of recipes, and references from information handbooks. In some cases it is helpful to utilize an intuitive learning condition, for example, a computing environment. In this way, activities utilizing computers are required to upgrade dynamic learning. This paper will give another method of showing the turbo machinery through Excel/VBA. A capable computer program which can change the method of your comprehension of the subject and assignments which won't be restricted to the classroom. This tool can be introduced among the students as well as among teachers. Providing students with this tool help them in getting rid of large calculations and it will also help them to see different variations in values which will help them to understand the concepts as well as it is a good way to improve the motivation of students towards the subject. It will also help teachers to teach different types of concepts not only just few concept as it takes time due to its lengthiness. Students can also use it as a tool in designing parts of the project. Besides solving the equations this tool can also provide how each parameter affects different forces. Therefore students can perform as many calculations just with a single click and without any mistake or being bored.