Symphony Enters Rig Testing

First tests focused on combustor aerodynamics. Written by Scott Powell, Senior Vice President of Symphony

Supersonic Symphony progress

We’ve made significant progress since first announcing that Boom will lead the development of Symphony in December 2022. Symphony is the purpose-built turbofan engine that will enable economical and reliable supersonic flight onboard Overture, Boom’s supersonic airliner.

At the Paris Air Show, Boom unveiled Symphony’s engine architecture by developing a one-third scale model of the engine.

In June 2023, Boom unveiled Symphony’s engine architecture at the Paris Air Show. Then in October, the Symphony team successfully completed the engine’s Conceptual Design Review (CoDR), a key engineering milestone that paved the way for us to start building and rig-testing Symphony hardware. 

I’m excited to share today that we’ve initiated Symphony rig testing, which will allow us to further refine our computational designs and continue our accelerated progress toward engine production. In total, we will conduct more than 30 Symphony rig tests in collaboration with our engine design partner Florida Turbine Technologies (FTT), a business unit of Kratos.

So let’s dig into rig tests already in progress.

Symphony combustor rig testing

Our first rig test focuses on analyzing the pressure drop through Symphony’s combustor section at multiple airflow and pressure rates. This test also evaluates the division of airflow between the combustor and secondary air systems. The learnings from these studies allow us to calibrate our digital computational tools and enable design improvements that ensure consistent airflow and pressure throughout the combustor. Ultimately, this is one of the many ways that we’ll optimize engine efficiency to deliver supersonic flight that’s accessible to millions of passengers worldwide.

  The smoke was injected through the fuel nozzles to visualize airflow.

This test is being conducted at FTT’s design and test facility in Jupiter, Florida. The combustor rig itself was created in the span of 8 weeks using the latest Stereolithography (SLA) 3D printing technology. The SLA process meticulously builds up a photosensitive resin, layer by layer, which is cured by UV lights after each pass. This additive manufacturing process resulted in a full-scale, 1/8th section of the Symphony combustor module – including the physical compressor diffuser, combustion chamber, fuel nozzles, and secondary air system passages. The full test unit is approximately four feet long by two feet tall and includes nearly 80 static and total pressure ports. 

This is a computer visualization of airflow through the various combustor module sections.

The initial combustor rig test is the first phase of a two-phase pressure drop test, spanning 6 weeks. From here, we’ll next move to additional combustor tests that evaluate nozzle spray distribution and droplet size, exit temperature profiles, and emissions data – both at sea level and simulated cruise altitude for Overture at 60,000 ft. Beyond the combustor tests, all major Symphony components will be individually evaluated and optimized. These milestones then pave the way for Boom to start holistic integrated power plant system testing. 

Rig testing explained

Rig tests isolate engine components to evaluate their performance characteristics across a variety of simulated flight conditions and engine power settings. A series of full or sub-scale rig tests are used to verify design characteristics and validate computational tools. Rig tests are used to evaluate the performance of a broad spectrum of engine components that include the combustor, inlet and exhaust acoustics, fan performance, compressor aerodynamics and aeromechanics, bearing damper and heat generation, fuel and lube pump systems, and more.

What’s next for Symphony?

Unfortunately, I need to keep my lips sealed on other developments with Symphony until the Farnborough International Airshow, which begins in a few weeks. What I can say is that we’ll have updates around the innovative ways we’re accelerating Symphony testing so we can iterate quickly and identify and mitigate risk earlier in development. There’s also exciting news to be revealed related to the production of Symphony. That’s probably more than I should be sharing ahead of the air show, so stay tuned for more details on Symphony and our continued progress toward production.   

– Scott Powell


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