Vijay Desai

Studies on Influence of Injection Timing and Diesel Replacement on LPG-Diesel Dual-Fuel Engine

Reducing the emissions and fuel consumption for IC engines are no longer the future goals; instead they are the demands of today. People are concerned about rising fuel costs and effects of emissions on the environment. The major contributor for the increased levels of pollutants is the Diesel engines. Diesel engine finds application in almost in all fields, including transportation sector such as buses, trucks, railway engines, etc. and in industries as power generating units. In the present work an attempt is made for effective utilization of diesel engine aiming for reduction in fuel consumption and smoke density. This is achieved by some minor modifications in diesel engine, so as to run the existing diesel engine as a LPG-Diesel dual-fuel engine with LPG (Liquefied Petroleum Gas) induction at air intake. The important aspect of LPG-Diesel dual-fuel engine is that it shows significant reduction in smoke density and improved brake thermal efficiency with reduced energy consumption. An existing 4-S, single cylinder, naturally aspirated, water-cooled, direct injection, CI engine test rig was used for the experimental purpose. With proper instrumentation the tests were conducted under various LPG flow rates, loads, and injection timings. The influence of the diesel replacement by LPG on smoke density, brake specific energy consumption and brake thermal efficiency were studied. The optimal diesel replacement pertaining to the maximum allowable LPG gas flow limits could be assessed with these experiments. The influence of the injection timing variation on the engine performance and smoke density were analyzed form the experimental results. It was also observed that beyond half load operation of the dual-fuel engine, the brake thermal efficiency increases with diesel replacement, and at full load up to 4% improvement was observed compared to full diesel operation. At full load reduction in smoke density up to 25–36% was observed compared to full diesel operation. At advance injection timing of 30°btdc the performance was better with lower emissions compared to normal and retarded injection timings.© 2003 ASME

Evaluation of Wear Behaviour of Metal Injection Moulded Nickel Based Metal Matrix Composite

Metal injection moulding (MIM) is a near-net shape manufacturing technology for producing intricate parts, cost-effectively. MIM comprises combined techniques of plastic injection moulding and powder metallurgy. The present study focused on the development of the binder and fabrication of defect free MIM component. A wax-based binder system consisting of paraffin wax (PW), low density polyethylene (LDPE), polyethylene glycol (PEG-600) and stearic acid was established for MIM of NiCrSiB (70% Wt.) + Cr3C2-NiCr (30% Wt.) nickel based metal matrix composite (NMMC) powder. The feedstock was characterised through rheological properties at different temperatures. Injection temperature was determined from the rheological investigation of the feedstock having the 56% powder loading and 44% binder by volume. Sintering process was carried out with the temperature cycle in the range of 1250–1300 ∘C under hydrogen purged atmosphere. The MIM components showed good and acceptable shrinkage in linear dimensions. The mechanical properties and wear behaviour of NMMC was studied using a pin-on-disc apparatus with alumina disc.Tests were performed under dry sliding conditions at room temperature and elevated temperatures of 200 and 400 ∘C. Results shows that wear rate is maximum at 400 ∘C for 40 N and lowest at room temperature for 10 N. Further wear mechanism was analysed using scanning electron microscope (SEM).

System simulation approach for helicopter autopilot

This paper discusses an approach for system simulation of an autopilot system designed for a Bell helicopter model. The flight controls for the helicopter is designed in Matlab/Simulink and the same is visualized in X-Plane flight simulator. The approach involves software in loop simulation method where controls are designed in Matlab/Simulink and the responses are observed on X-Plane plant. The interaction between the Matlab/Simulink and X-Plane is through UDP. A parameter identification of the X-Plane model is carried out from data obtained through UDP. This simulation setup is a good way to learn the intricacies of systems development, plant identification and control.

Development of Guided Autonomous Navigation for Indoor Material Handling Applications

In recent past emphasis on material handling requirements in industry has gone up considerably and in particular several researchers have attempted to improve the indoor material handling. In this paper an autonomous navigation system is implemented on a trolley for applications intending to move the trolley along a predefined path without human operator assistance. The trolley operates in two modes: Learning mode and Autonomous mode. In the learning mode the operator has to manually move the trolley along a path, it has to follow autonomously when the autonomous mode is activated.

System identification for helicopter longitudinal dynamics model - best practices

For estimation of mathematical model and parameters of a system, the system identification has been widely applied in various domains such as the automatic control, aviation, spaceflight, civil and mechanical engineering, medicine, biology, chemical processes, marine ecology, geology etc. The main aim of this work is to perform preliminary studies to design a control law for helicopter model making it as autopilot. X-plane flight simulator will be used with Matlab wherein the estimated model is imported and simulated for its practical behavior. A longitudinal state-space model of the Puma, SA330 research helicopter is used as a reference model. First, the model is described and with standard reference input test signals, output data set is generated, then this input-output dataset is used for system identification purpose. Both traditional methods such as subspace & prediction-error minimization (PEM) method along with modern ways of identification methods such as neural networks are used. A practical comparison between used identification methods and best suitable type of input for estimation is discussed.

Effects of 4.5% Copper Addition and Melt Treatment on Microstructure and Wear Properties of Al-7Si Alloy

The present study describes the effects of addition of 4.5 wt% of copper on microstructure and wear properties of cast Al-7Si base alloy. Grain refiner (1 wt% of Al-1Ti-3B) and grain modifier (0.2 wt% of Al-10Sr) were added together to Al-7Si base alloy and Al-7Si-4.5Cu alloy and effect of alloy composition, microstructure and normal pressure on wear properties were studied. Results indicated that combined grain refined and modified Al-7Si-4.5Cu alloys had uniformly distributed α-Al grains, eutectic Al-Si and fine CuAl2 particles in the inter dendritic region. In both alloys (Al-7Si and Al-7Si-4.5Cu) the wear properties improved after combined melt treatment. The addition of 4.5% copper resulted in improved wear characteristics as compared to both untreated and treated Al-7Si alloys. SEM / EDS analysis were carried out on cast alloys and worn surfaces.

Development and Characterization of Al-Si-Cu FGM Using Centrifuge Technique

In this work Al-Si-Cu Functionally Graded Material (FGM) is developed using centrifuge technique. The method used in this work to produce FGM is totally different compared to other centrifugal process which helped in producing solid cylindrical parts. The FGM is characterized through Microstructure and Hardness and it is found that the Cu segregated at the bottom of the casting and Si at the top due to the density difference. Similarly the hardness and the ultimate tensile strength at the bottom of the casting and at the top of the casting region is more when compared to region in-between the top and bottom of the casting.

Characterization of aircraft electro hydrostatic actuator using virtual instrumentation

In Aerospace industry, implementation of Automated Test System (ATS) at the assembly and manufacturing floor improves characterization accuracy and plays a vital role to substantiate the airworthiness of the aircraft components. It is very useful in realizing high quality standards of aircraft components by virtue of meeting predefined acceptance test criteria. This paper outlines comprehensive design and development of the noise and vibration monitoring system at assembly and manufacturing floor for characterization of Electro Hydrostatic Actuator (EHA) of aircraft using progressions in virtual instrumentation. In aircraft, the flight control actuation system are powered by centralized hydraulic pumps that are driven by the aircraft engine, while the back-up system are driven by electric or ram turbines. Distributed control of electric actuators with integration of control function in Flight Control Computer (FCC) and power electronics is a cost effective approach. EHA does also play a significant role in electrical actuation system, which use distributed electric power drive in driving a hydraulic transmission system. Hence, before integrating with the primary flight control actuation systems in aircraft, EHAs are required to be subjected to noise and vibration characterization, as part of assembly and manufacturing level testing. This method is intended at replacing the monotonous and time consuming traditional method of noise and vibration characterization of the electric actuators at assembly and manufacturing floor and to improve the reliability of the electric actuation components supplied to the aircraft manufacturers. The tests have been performed using a LabVIEW controlled virtual instrument measurement system that monitored the noise and vibration waveform with reference to the tacho signal.

Effect of Process Parameters on Centrifugally Cast Al-Si FGM

Functionally Graded Materials (FGM) are such kind of materials wherein the properties and structure are varied from one end of the cast to the other intentionally. Centrifuge technique has been used in this study to produce Al-Si FGMs. Several process parameters determine the microstructure and the distribution of phases in the FG casting. These parameters include the size and initial concentration of alloying element, the centrifugal force, solidification rate, cooling rate. In this work an attempt has been made to produce FGMs using three different process variables such as mold temperature, melt temperature and mold rotational speed, their effect on the structure and properties. For this study Al-17wt%Si is used. From the results it is seen that for a particular melt and mold temperatures by increasing the mold rotation speed enhances the segregation of the Si particles at the one end of the casting. Similarly increasing mold or melt temperature only, increases the segregation.

LabVIEW FPGA based Software Implementation for an Automated Test System of Shafts used in High Lift System of an Aircraft

Shafts used in the high lift system (wings of a plane) of an aircraft undergo extreme load conditions during takeoff and landing. Performance of shaft deteriorates along the life span of it. The failure of shaft can lead to a major catastrophe. Therefore, to ensure the safety of passengers, there is a need to develop a test system which can subject different shafts to various loads to which they are designed for and test them for their life cycle. This paper presents implementation of a test system built using LabVIEW – Field Programmable Gate Array (FPGA) which is able to simulate different load conditions on shaft. The real time data of torque and speed values are recorded using FPGA card. Software design of test system and results obtained for a test shaft are discussed in this paper.