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arxiv: 2604.15401 · v1 · submitted 2026-04-16 · ⚛️ physics.flu-dyn

Endwall and leading-edge film cooling of turbine blades in a hydrogen-fueled rotating detonation combustor-turbine coupled system

Yeqi Zhou , Songbai Yao , Jingtian Yu , Weijia Qian , Ping Wang , Wenwu Zhang This is my paper

Pith reviewed 2026-05-10 09:55 UTC · model grok-4.3

classification ⚛️ physics.flu-dyn
keywords film coolingrotating detonation combustorturbine bladesendwall coolingleading edge coolinghydrogen combustionnumerical simulationflow stability
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The pith

In a hydrogen-fueled rotating detonation combustor-turbine system, combining endwall and leading-edge film cooling reduces blade surface temperatures and improves flow stability.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

This paper examines how to cool turbine blades in a system that pairs a rotating detonation combustor burning hydrogen with a turbine. Through three-dimensional computer simulations of the entire flow field, it tests different ways to deliver cooling air through holes in the endwall and at the blade leading edge. The results indicate that using both types of cooling together lowers the temperatures on the blade surfaces, makes the flow through the turbine more steady, and better shields the blades from heat damage. Comparisons show that round holes work as well as slots but use less cooling air, and angled cooling at the leading edge attaches better to the surface despite the pulsing flow from the detonation.

Core claim

The study finds that in a hydrogen-air rotating detonation combustor coupled to a turbine, the combined use of endwall film cooling and leading-edge film cooling lowers blade surface temperatures, enhances the stability of the turbine flow field, and provides better blade protection. Circular holes for endwall cooling require less coolant than slot holes while delivering similar cooling. A vertical-inclined configuration for the leading-edge cooling achieves higher efficiency and better jet attachment than a purely vertical one when exposed to the unsteady detonation flow. The oscillating flow from the upstream detonation promotes the downstream spreading of the cooling jets from the blades.

What carries the argument

The central mechanism is the film cooling jets from endwall circular or slot holes and leading-edge vertical or inclined holes interacting with the oscillatory rotating detonation wave, which influences jet attachment and diffusion.

If this is right

  • Circular holes consume less cooling air than slot holes for comparable endwall cooling performance.
  • The vertical-inclined leading-edge scheme offers higher cooling efficiency and better secondary flow attachment than the vertical scheme.
  • The rotating detonation wave flow aids the downstream diffusion of the film cooling jets compared to cases without it.
  • Blade surface temperatures decrease, leading to improved protection under the high-heat conditions of the detonation-turbine system.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Engine designers might achieve higher overall efficiency by operating at elevated temperatures enabled by this cooling method.
  • Similar cooling configurations could be adapted for other unsteady combustion turbines beyond rotating detonation types.
  • Manufacturing turbines with circular cooling holes may reduce coolant requirements and simplify designs.
  • Experimental tests in actual rotating detonation engines could validate the simulated temperature reductions.

Load-bearing premise

The numerical model correctly predicts how the pulsing detonation wave affects the sticking and spreading of the cooling air jets on the blade surfaces.

What would settle it

Measuring actual blade temperatures and flow patterns in a physical hydrogen-fueled rotating detonation combustor-turbine rig, with the proposed cooling holes, and checking if they match the simulated reductions and stability gains would test the findings.

Figures

Figures reproduced from arXiv: 2604.15401 by Jingtian Yu, Ping Wang, Songbai Yao, Weijia Qian, Wenwu Zhang, Yeqi Zhou.

Figure 1
Figure 1. Figure 1: Schematic of the computational domain: (a) [PITH_FULL_IMAGE:figures/full_fig_p004_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: Schematic of inner-outer endwall film cooling: (a) Slots holes and (b) Circular holes. Two distinct design schemes for the leading-edge film cooling holes are examined. The first design uses traditional vertical holes, while the second employs combined holes to enhance the cooling effect along the middle section of the leading edge. Both configurations consist of three rows of film cooling holes at the bla… view at source ↗
Figure 3
Figure 3. Figure 3: Schematic of leading-edge film cooling: (a) Arrangement of hole rows, (b) Film cooling hole layout, (c) Vertical-angle scheme, and (d) Vertical-inclined scheme. 2.2 Boundary conditions The combustor inlet is specified as a mass flow inlet, with a stoichiometric hydrogen-air [PITH_FULL_IMAGE:figures/full_fig_p005_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: Configuration of initial and boundary conditions: (a) Fully coupled RDC and (b) Single [PITH_FULL_IMAGE:figures/full_fig_p006_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: Flow field pressure contours and pressure profiles at different resolutions. [PITH_FULL_IMAGE:figures/full_fig_p007_5.png] view at source ↗
Figure 6
Figure 6. Figure 6: Contour plots of the coupled flow field: (a) Temperature and (b) Pressure. [PITH_FULL_IMAGE:figures/full_fig_p008_6.png] view at source ↗
Figure 7
Figure 7. Figure 7: Pressure gradient contour plot of the interaction between the oblique shock wave and the [PITH_FULL_IMAGE:figures/full_fig_p008_7.png] view at source ↗
Figure 8
Figure 8. Figure 8: Flow field near the blade: (a) Local zone and (b) Streamlines. [PITH_FULL_IMAGE:figures/full_fig_p009_8.png] view at source ↗
Figure 9
Figure 9. Figure 9: Temperature contour plot of (a) an uncooled blade and (b) a single blade with [PITH_FULL_IMAGE:figures/full_fig_p009_9.png] view at source ↗
Figure 10
Figure 10. Figure 10: Outer endwall surface contour plot with film cooling holes: (a) Temperature and (b) [PITH_FULL_IMAGE:figures/full_fig_p011_10.png] view at source ↗
read the original abstract

This study performs a three-dimensional numerical simulation of the coupled flow field in a hydrogen-air rotating detonation combustor (RDC)-turbine system to evaluate the effectiveness of different film cooling strategies for the turbine blades. The results demonstrate that combining the endwall cooling with leading-edge film cooling effectively reduces blade surface temperatures while improving turbine flow field stability and blade protection. For endwall cooling, numerical simulations compare circular and slot hole configurations. Circular holes consume less cooling air than slot holes while maintaining comparable cooling performance, making them the preferred choice. For the leading-edge film cooling, both the vertical and the vertical-inclined schemes are examined. The vertical-inclined scheme demonstrates higher cooling efficiency and improved secondary flow attachment, ensuring greater stability under the oscillatory effects of the detonation flow. Additionally, the flow fields of film-cooled turbine blades with and without the propagation of the rotating detonation wave are compared, revealing that the upstream rotating detonation flow field facilitates the downstream diffusion of secondary film cooling jets.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

3 major / 2 minor

Summary. The paper presents three-dimensional numerical simulations of a hydrogen-air rotating detonation combustor (RDC) coupled to a turbine stage, evaluating film-cooling configurations on the turbine blades. It compares circular versus slot holes for endwall cooling and vertical versus vertical-inclined holes for leading-edge cooling, concluding that the combined endwall-plus-leading-edge approach lowers blade surface temperatures, stabilizes the flow field, and improves protection under the unsteady detonation inflow. Circular holes are reported to use less coolant than slots while achieving comparable performance; the vertical-inclined leading-edge scheme is said to provide superior jet attachment and cooling efficiency. The study also claims that the upstream rotating detonation wave promotes downstream diffusion of the secondary cooling jets.

Significance. If the reported temperature reductions and stability improvements are physically accurate, the work would be significant for the design of integrated RDC-turbine systems in hydrogen propulsion, offering concrete geometric guidance on minimizing coolant consumption while mitigating the high-frequency unsteadiness that challenges conventional film cooling. The comparative CFD cases constitute a first step toward quantifying how detonation-induced oscillations interact with film-cooling jets.

major comments (3)
  1. [Numerical setup] Numerical setup section: the manuscript supplies no information on mesh resolution, cell count, y+ values, turbulence closure (RANS or URANS model), time-step size, or Courant-number criteria used to resolve the high-frequency pressure and velocity oscillations imposed by the rotating detonation wave. Without these details the link between the computed jet attachment, temperature fields, and the physical claim cannot be verified.
  2. [Results] Results section (comparative cases): no grid-convergence study, turbulence-model sensitivity test, or experimental benchmark for film-cooling effectiveness under unsteady detonation inflow is presented. Consequently the reported advantages of circular holes over slots and of the vertical-inclined leading-edge scheme over the vertical scheme rest on unverified numerical outputs.
  3. [Discussion] Discussion of detonation-wave effects: the assertion that the upstream rotating detonation flow “facilitates the downstream diffusion of secondary film cooling jets” is stated without quantitative metrics (e.g., jet penetration depth, mixing rates, or temperature-drop magnitudes) or any validation against known unsteady film-cooling data, leaving the central stability-improvement claim unsupported.
minor comments (2)
  1. [Figures] Figure captions and legends should explicitly label the detonation-wave propagation direction, the locations of the cooling holes, and the temperature scale ranges for all contour plots.
  2. [Abstract and Conclusions] The abstract and conclusions should report at least one quantitative cooling-effectiveness or surface-temperature reduction value for each configuration to allow readers to judge the magnitude of the claimed improvements.

Simulated Author's Rebuttal

3 responses · 0 unresolved

We thank the referee for the constructive and detailed comments, which help improve the clarity and rigor of our work on film cooling in the RDC-turbine system. We address each major comment point by point below and will revise the manuscript to incorporate additional details and supporting evidence where feasible.

read point-by-point responses

  1. Referee: [Numerical setup] Numerical setup section: the manuscript supplies no information on mesh resolution, cell count, y+ values, turbulence closure (RANS or URANS model), time-step size, or Courant-number criteria used to resolve the high-frequency pressure and velocity oscillations imposed by the rotating detonation wave. Without these details the link between the computed jet attachment, temperature fields, and the physical claim cannot be verified.

    Authors: We agree that these numerical parameters are essential for verifying the results and ensuring reproducibility. In the revised manuscript, we will add a dedicated paragraph in the Numerical Setup section specifying the mesh resolution and total cell count, y+ values (kept below 1 for wall-resolved boundary layers), the turbulence closure model (URANS), time-step size, and Courant-number criteria used to capture the detonation-induced oscillations. revision: yes

  2. Referee: [Results] Results section (comparative cases): no grid-convergence study, turbulence-model sensitivity test, or experimental benchmark for film-cooling effectiveness under unsteady detonation inflow is presented. Consequently the reported advantages of circular holes over slots and of the vertical-inclined leading-edge scheme over the vertical scheme rest on unverified numerical outputs.

    Authors: We acknowledge the lack of a grid-convergence study and turbulence-model sensitivity analysis in the submitted version. We will perform and include a grid-convergence study in the revised manuscript to demonstrate result independence from mesh density, along with a short discussion of the turbulence model selection. For experimental benchmarks under unsteady detonation inflow, no such data currently exist in the literature to our knowledge; we will explicitly note this as a limitation while positioning the comparative CFD cases as an initial quantitative exploration of the interactions. revision: partial

  3. Referee: [Discussion] Discussion of detonation-wave effects: the assertion that the upstream rotating detonation flow “facilitates the downstream diffusion of secondary film cooling jets” is stated without quantitative metrics (e.g., jet penetration depth, mixing rates, or temperature-drop magnitudes) or any validation against known unsteady film-cooling data, leaving the central stability-improvement claim unsupported.

    Authors: The assertion stems from side-by-side comparison of the flow fields with and without the detonation wave. In the revision, we will augment the Discussion section with quantitative metrics including jet penetration depths, mixing rates (via appropriate scalar transport measures), and temperature-drop magnitudes to support the diffusion claim. Relevant references to unsteady film-cooling literature will also be added for context. revision: yes

Circularity Check

0 steps flagged

No circularity: results are direct CFD outputs with no derivations or fitted predictions

full rationale

The paper reports outcomes from comparative three-dimensional numerical simulations of different film-cooling hole geometries and configurations under imposed rotating-detonation inlet conditions. No equations, parameter fits, uniqueness theorems, or self-citations are invoked as load-bearing steps that reduce the reported temperature reductions or stability improvements to the inputs by construction. The central claims follow directly from the simulation cases themselves, satisfying the criterion for a self-contained, non-circular analysis.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Abstract provides no explicit free parameters, axioms, or invented entities; all modeling assumptions remain implicit in the CFD approach.

pith-pipeline@v0.9.0 · 5494 in / 935 out tokens · 30500 ms · 2026-05-10T09:55:10.674344+00:00 · methodology

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Reference graph

Works this paper leans on

3 extracted references · 3 canonical work pages

  1. [1]

    S. Zhou, F. Liu, H. Ning, N. Hu, Experimental investigation on a rotating detonation combustor with the pulse operating frequency of 10 Hz, Acta Astronautica, 215 (2024) 642-652. [9] G. Vignat, D. Brouzet, M. Bonanni, M. Ihme, Analysis of weak secondary waves in a rotating detonation engine using large-eddy simulation and wavenumber-domain filtering, Comb...

    work page 2024

  2. [2]

    Fievisohn, R

    R.T. Fievisohn, R. Battelle, M. Karimi, C. Klingshirn, Operation of a Fully Integrated Rotating Detonation Combustor in a T63 Gas Turbine Engine, in: ASME Turbo Expo 2024: Turbomachinery Technical Conference and Exposition, 2024. [25] L. Su, F. Wen, Analysis of coupling supersonic turbine stage with rotating detonation combustor under different turbine pa...

    work page 2024

  3. [3]

    Shine, S.S

    S.R. Shine, S.S. Nidhi, Review on film cooling of liquid rocket engines, Propulsion and Power Research, 7 (2018) 1-18. [43] J. Zhang, S. Zhang, C. Wang, X. Tan, Recent advances in film cooling enhancement: A review, Chinese Journal of Aeronautics, 33 (2020) 1119-1136. [44] J. Tian, Y . Wang, J. Zhang, X. Tan, Numerical investigation on flow and film cooli...

    work page 2018