Role

Turbomachinery Development Engineering Associate

• Owned Development of a Turbine Wheel Modal Test Apparatus

  • Sized/Procured Test Apparatus & Designed in Siemens NX

  • Assembled, Calibrated, & Activated Test Apparatus

  • Sampled & Established Modal Response Database for Turbines

  • Designed a Custom Front Panel Express Electronic Enclosure

In order to qualify the Merlin Engine for human spaceflight, SpaceX needed to showcase a solid understanding of the modal response of the Merlin turbine wheels to NASA. When I returned to SpaceX upon graduation, they started a process of characterizing turbine wheels but it was inefficient, as it took hours to sample a single turbine wheel. My responsibility was to find a new way to characterize turbine wheels in a faster manner that was both repeatable & reliable.

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The test apparatus consisted of custom hardware I designed to support the Merlin turbine wheel and a servo-motor for indexing purposes. The instrumentation involved was an impulse hammer to excite all frequencies and a laser doppler vibrometer to record the velocity response at the location of interest. The data was modeled as a single degree of freedom (SDOF) system to determine the natural frequency of each blade of the turbine wheel. Modal response characterization is of importance as it can provide insight into blade-to-blade variation and how the global response deviates from the predicted for reasons such as manufacturing imperfections.

The key factors for this application was maintaining a manageable inertia mismatch ratio and considering the torque required for acceleration & deceleration. Having a high inertia mismatch ratio could result in continuous overshooting & make calibrating near impossible. As the use of this servo-motor was for indexing purposes only, speed & RMS torque are not of interest. In addition, I confirmed that all hardware purchased could be utilized for future Raptor turbine wheel characterization.

Once I received all the hardware, I fully assembled the test apparatus and prepped it for operation. This included securing & assembling all components through custom hardware, installing wiring & control switches, and calibrating the servo-motor system. In addition, I ran an experimental studies to test various methods of damping for noise reduction, showcased repeatability, and completed a control-study. Upon activation, I had created a modal test setup that was highly accurate/repeatable and was able to reduce sampling time from hours to minutes.

I designed an electronic enclosure to house all electronics, buttons, and switches, and this was done using Front Panel Express. The enclosure featured fan cutouts for ventilation & cooling purposes, connectors cutouts for making it a plug-and-use system, buttons/switches cutouts for trivial operation, as well as an emergency stop feature. I imported the panel designs into the Siemnes NX, where I generated a 3D CAD with all components, screws, standoffs, etc.