Pamraat Parmar

One of the fundamental parameters required for the characterization of any combustion system is temperature (the others are the total pressure and partial pressure of the gas components) and is paramount for diagnosing combustion efficiency. The present study involves the development of a high-speed temperature sensor using tunable diode lasers. The goal is to design and develop a Tunable Diode Laser Absorption Spectroscopy (TDLAS) temperature sensor to monitor path averaged gas temperature with high temporal resolution for combustion application.

The method is based on the Beer-Lambert law for absorption spectroscopy. H₂O vapour is selected as the target absorbing species as it is naturally present in the combustion exhaust as a major combustion product and has a rich absorption spectrum throughout the infrared. Here, a scanned wavelength 2-line thermometry method is employed where the ratio of integrated absorbance for two transitions with different temperature dependence is a function of the gas temperature. The sensor is first validated in a premixed methane/air flame stabilized in a standard McKenna burner for known operating conditions. Exhaust gas temperature measurements from a swirl stabilized non-premixed methane/air flame for varying global equivalence ratios are then conducted to demonstrate the robustness and stability of the sensor.

A molecule can absorb a particular wavelength of photon and get excited to next quantum level. As a result, the intensity of laser exiting the flame isn't the same as when entering, as shown in the figure above. Laser Absorptive Spectroscopy (LAS) basically exploits the fact that the characteristics of absorption done by a molecule for a given wavelength of light has dependence on the temperature of the absorbing molecule. If sweep over a wavelength is created using tunable diode laser, a dip in intensity is observed at a particular frequency, which is called absorption peak. The location, shape and size of the absorption peak are used to determine temperature using Beer-Lambert's law.

Two DFB tunable diode lasers of differnet wavelengths were used with ±1 nmtunability. They could be tuned by varying current or temperature. In the current study, temperature is kept constant and laser is being tuned using current, considering the less response time involved current control. The lasers had to be calibrated for laser current and laser temperature. Following figure shows callibration chart for 1343 nm laser.

Following shows the photo of experimental setup. The combination of pinhole and beam splitter was used to reduce the laser optical power to working range of the detector. Pinhole also reduces the beam diameter, so that the entire beam falls within the detector region. For high temperature measurements, Mckenna flat flame burner is operated at calibrated conditions. The beam of laser passes over Mckenna burner at 15 mm distance.

The results of experiments are listed below. Coherent Anti-stokes Raman Spectroscopy (CARS) is another non-intrusive temperature measurement technique used for point measurement of temperature and it is known to be very accurate, however, the setup is extremely bulky and the data sampling is relatively slow. For the sake of the validation of TDLAS technique, the comparison is made with theoretical predictions and CARS measurement.

The study is about analyzing the aerodynamic effects of oscillations of a wing. A computer code is developed for simulating inviscid unsteady flow over thin wing. The numerical solutions are compared with already available Theodersen theory for sinusoidally oscillating wing. Experimental setup is designed and built, though no final experimental data is extracted. A Labview code was developed for controlling the stepper motor used to impart oscillations to the wing.

Github Link: https://github.com/pamraat/port-aeroelasticity
https://github.com/pamraat/port-VLM
Notes: To operate this code, you'll need a valid LabVIEW license, MATLAB license and a compatible NI instrument.

The oscillations are characterized by sinusoidally varying frequecies of a sinusoidal motion. A stepper motor detects only the falling peak of digital signal to change its state. Our motive was to achieve oscillations of sinusoidal character. Hence the pulses were given such that time gap between two pulses varied sinusoidally. To achieve this, we change the direction after half time period. This can be done by sending an extra signal to direction pin which is high initially and then drops to low at half time. The digital signal generation of the aforementioned signal is shown in the figure above. Due to security reasons, the video of experiment are not shared here.

This is a project of desigining structural element which is modular, i.e., only single part is required to build a structure of any shape and size. The project was done under the perview of Cornell University Sustainable Design (CUSD) team.

The Sustainable Mobility Shelter Team operates with the mission of reimagining the transit network of Tompkins County through the use of empathy fieldwork, systems design tools, and user-centric design. Previously the interdisciplinary team of designers, engineers, coders, planners, and systems students have developed, iterated, and pitched a tech-focused bus shelter to provide a safe, welcoming, and informative experience specifically for TCAT riders. The shelter design concept itself has progressed far enough to exist as a functional prototype in the team's Carpenter Hall lab space, with one suitable first deployment site being the A-lot parking on the Cornell campus. Currently our main stakeholder is Light Green Machines LLC (LGM), a local startup that is developing a small hybrid bus with a composite chassis. While the goal of the shelter design team is to design an innovative bus shelter that would match the LGM bus system, the masterplan team focused this semester on exploring two use cases (the airport/shuttle and the Gadabout/on-demand) that could be future applications of the entire LGM system (including the hybrid bus and the bus shelter). The design of structure is shown in the figure above.

The figure above shows a single module formed using three elements. The elements are shown in the following figure. These elements are having ball-socket joints with each other, and are extendable, making it possible to make triangle with wide variety of combinations of angles.

The above shown design was complex and may require certain skills to assemble. To make it more assemble-friendly it was redesigned to the following shape. This design was 3D printed and used to create the bus shelter prototype.

The 737-800 is one of the most dependable aircraft ever created and while it's reliability and safety record is remarkable, Delta Airlines' fleet of seventy seven 737-800s is aging. Identifying the potential shortcomings of the different subsystems using an FMEA, breaking down the failure points of high risk subsystems using fault tree analysis and performing survivability vs cost analysis on the fuselage with allow for a thorough report of what Delta should expect moving forward and actions that can be taken to maximize value and longevity with the current fleet while also ensuring the aircrafts are safe for use. The flow chart of project process is shown below.

Delta Airlines is the 2nd largest airline in the world by customers served with a net revenue of 4.8 billion dollars. Airlines also run on a tight budget, as a new 737-MAX would cost around a hundred million dollars, which would be about 2% of total profit last year. Hence, maximizing the current fleet is critical to Delta, however, it has a diverse fleet of old and new with some of their older 737-800s being purchased in 1998 and none more recent than 2010. Aircrafts such as these don't have a specific lifespan, but depend more on multiple components within the aircraft that wear over time. As an aircraft ages, especially past certain service milestones, the annual maintenance cost increases. Ultimately, a 737-800 cannot surpass 75k flight cycles without entering a prohibitively expensive maintenance plan. At every 2 and 10 year intervals, Federal Regulations stipulate “C” and “D” checks, which respectively cost airlines approximately $2m and $6m per plane.
Our analysis shows Delta's fleet should be retired before the plane's expected age at the 75k flight cycle mark. We recommend retirement when it's anticipated market value, which is a function of fuselage reliability and engine Limited Life Part status, depreciates below the cost of maintenance. This can

A detailed FMEA analysis of Boeing 737-800 was done. The summary of this FMEA is shown in the figure below.

Detailed fault trees were created to estimate failure rate of fuselage. Non-electronic Part Reliability Data (NPRD-16) was used to assign the failure rates, assuming exponential failure model. Using the fault tree analysis the failure rate of each major component was deduced and based on that, maintenance schedule was determined. The maintenace cost was determined from the schedule and the aforementioned conclusions were derived.