Papers by sreelal sreedhar
Lecture notes in mechanical engineering, Jul 24, 2022
2019 4th International Conference on Electrical, Electronics, Communication, Computer Technologies and Optimization Techniques (ICEECCOT), 2019
Testing is an essential part of any aero engine development programme. Combinations of flight and... more Testing is an essential part of any aero engine development programme. Combinations of flight and safety critical hardware and software are tested on various platforms before integrating on engine. Extensive tests are carried out to exercise the engine in various modes to ensure reliable performance. One of the vital element of on board safety critical embedded controller software is control algorithms also known as Control Law (CLAW). The Control Laws are coded in C language by the Software House and are extensively tested with the participation of the Independent Verification and Validation (IV & V) group. Various validation techniques are emoloyed before onboard safety critical software flies. A method known as Non- Real Time (NRT) testing is adopted to test the on board safety critical code. In this paper a new approach to conduct NRT testing is addressed. This method helped engine house for formal clearance of onboard safety critical software. The new approach i.e. Gray Box Non...
2018 5th IEEE Uttar Pradesh Section International Conference on Electrical, Electronics and Computer Engineering (UPCON), 2018
Typically accelerometers are employed in ground tests, the results of which form part of input to... more Typically accelerometers are employed in ground tests, the results of which form part of input to airworthiness checks and therefore need performance reverification at specified or regular intervals for measurement and control. Towards the objective, sensor calibrations are performed using comparison method at Calibration Laboratory where the setup consists of electro-dynamic shaker which has an armature with attached reference sensor. The reference accelerometer's armature had become non functional since the coil got damaged and therefore not available for calibration tasks. Support services not being offered by Original Equipment Manufacturer or other sources due to obsolescence is common scenario and it poses several challenges and opportunities. Approach and efforts taken towards ameliorating the situation involve analysing past constraints, root cause studies and implementing corrective actions, additional software development, hardware rectification, overcoming re-calibrat...
NDE methods can be classified into two categories-qualitative and quantitative. Qualitative metho... more NDE methods can be classified into two categories-qualitative and quantitative. Qualitative methods provide information on presence/ absence of flaws and Quantitative methods provide information on size of flaws. Quantitative NDE is essential for defect characterization and provides valuable information for further investigations. Turbine Rotor Blades are the highly critical rotating parts in aero engine and failure of a blade leads to the destruction of the entire down stream hardware and ultimate failure of the mission of the engine. Hence these blades are subjected to critical nondestructive examination by one or combination of methods. This paper presents typical case study of a Low Pressure Turbine (LPT) rotor blade where multiple NDE methods were used for detection and sizing of a defect. The information provided by these methods was further validated by metallurgical examination. The combination of NDE methods were proved to provide reliable data for quantitative defect chara...
Dead weight tester is a well known hydromechanical system which utilises Bernoulli's principl... more Dead weight tester is a well known hydromechanical system which utilises Bernoulli's principle to achieve a highest level of accuracy in its class. This makes it a primary standard which is internationally used in calibration laboratories. Hydraulic pressure sensors and reference standards are calibrated using cross float method where the hydraulic Dead weight tester is used as a highest accuracy pressure source/calibrator to maintain calibration traceability chain. Typically a Dead weight tester consists of piston cylinder assembly along with masses, hydraulic compressor with rotary piston, a collector port (where output pressure is made available for device under calibration) and an oil reservoir. Calibration using hydraulic Dead weight tester requires huge human efforts; it becomes more cumbersome when used at high pressure. It requires more man power when it is used to generate pressure at its highest range or near highest range as it is mechanically structured equipment. Ta...
Insight - Non-Destructive Testing and Condition Monitoring, 2013
ABSTRACT
During development of the aero engine, various methods are employed to characterize the component... more During development of the aero engine, various methods are employed to characterize the components. Aero engine consists of varieties of components and it is necessary to evaluate the characteristics of these parts for the testing. Various metrological and NDT methods are adapted to study and evaluate these components. Non-destructive testing (NDT) techniques are used to probe the structures, materials etc. and different techniques are employed to give increased probability of detection. Current paper discusses about the characterization of the starting nozzle of an aero engine. Starting nozzle is a complex critical component in the engine and hence needs higher integrity. Different methods like casting, additive manufacturing etc. are employed to realize the component. Hence various metrological and NDT methods are employed to evaluate the quality characteristics of the part. Paper discusses about surface analysis and sub-surface detection in the part under study. Results of the various methods like surface roughness, visual inspection, radiography, penetrant testing, are explained and discussed.
Journal of Failure Analysis and Prevention
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Papers by sreelal sreedhar