Ownership in this dataset is concentrated: the top five assignees among the 54 ranked companies account for 52.1% of the 674 records in scope, and the leading assignee alone holds 103 records. That said, the field is not a single-company monopoly — by tenth place, holdings drop to 20 records, showing a long tail of smaller filers below the concentrated top. Anyone doing competitive tracking should watch the leader’s continuation filings closely, since that portfolio is disproportionately large relative to the rest of the ranking.

Filings peaked at 52 in 2017 and fell to 2 by 2024, a 94% decline over the 2021-2024 span for which the data is considered complete. This does not necessarily mean the underlying R&D has slowed to the same degree — patent publication typically lags filing by around 18 months, so the 2025 and 2026 figures in this dataset are still incomplete and should not be read as continued decline. A more likely explanation is that core geometric claims in serpentine passages and rib turbulators have already been heavily filed, pushing new work toward narrower process or manufacturing claims that may not show up as strongly in this specific search string.

The overwhelming majority of records, 88.1% of 674, fall under IPC class F01D covering turbines and non-positive-displacement engines. Secondary classes include F02C for gas-turbine plants at 11.7% and F23R for combustion chambers at 7.4%, reflecting how cooling claims often extend into the surrounding engine architecture. Manufacturing-related classes such as additive manufacturing (B33Y) and powder metallurgy (B22F) each appear in under 3% of records, marking them as comparatively under-claimed relative to the core turbine classification.