Project Description
I am building a small gas turbine. The compressor section is two centrifugal stages on a common shaft, each in its own scroll housing (think sequential turbos). The combined pressure ratio is ~10:1.
I need a turbomachinery aerodynamicist to design — not just model — both impellers from the thermodynamic design point. I have rough V1 starter geometry (Zoo-generated), but it's a placeholder, not a target. I want you to design something materially better.
Design point
Stage Mass flow (test article) Inlet Exit (target) Operating RPM Inducer eye Ø Exit tip Ø Axial length envelope
S1 ~0.15 kg/s 1 atm, 25°C 3.3 atm, 150°C 60–100k Ø62 mm Ø95 mm (fixed by housing) ≤22 mm
S2 ~0.15 kg/s 3.3 atm, 50°C (intercooled production) / 150°C (test article) 11 atm, 280–350°C 60–100k Ø48 mm Ø78 mm (fixed) ≤20 mm
Both wheels share a Ø16 mm tie-bolt bore. They're a matched set — S1 exit feeds S2 inlet through an external crossover pipe.
Material: Inconel 625, Markforged Metal X (FFF metal printing process). Min printable feature ~2.8 mm; design with 3.0 mm safety margin. Open (unshrouded) impellers — tip clearance is set by the housing (1.0 mm budget).
What I'm asking you to design
Optimize whatever the model spec doesn't pin down: blade count (main + splitter), wrap angle, backsweep, splitter start position, blade angle distribution, hub contour, blade thickness profile. Target polytropic efficiency in the high 70s minimum, low 80s preferred. Surge margin appropriate for typical aero start/stop duty cycles.
Reference V1 used 12+12 blades on S1 and 10+10 on S2 with ~45° wrap and ~35° backsweep — these are placeholders, not constraints. You override them if your design intent says otherwise.
Tools
Use a real turbomachinery aero design tool — CFturbo, Concepts NREC AxSTREAM, ANSYS Vista CCD, NUMECA, or equivalent. CAD-only ports of meanline calculations don't count. If you want to run 3D CFD verification, that's welcome but optional. Native CAD output via SolidWorks / NX / CATIA / Creo is fine; export to STEP and IGES.
Deliverables
2× fully-designed centrifugal impellers as 3D parametric models
Native CAD files + STEP + IGES exports
Performance map (PR vs corrected mass flow at design RPM, plus surge/choke estimates)
Design report (1–3 pages): blade-count rationale, wrap/backsweep/splitter choices, polytropic efficiency estimate, surge margin estimate, key design assumptions, AM-printability verification
Build-orientation recommendation for Metal X
Working approach
Kickoff: review the design point together; you confirm feasibility and flag any conflicts.
Stage 1: meanline / 1D design, blade counts and angles agreed.
Stage 2: 3D blade definition, hub contouring, STEP export, AM check.
Stage 3: final report, revisions, native files.
Regular screenshots / lightweight viewer files for interim checks.
Required experience
Centrifugal compressor aerodynamic design (automotive turbocharger, microturbine, APU, or aerospace turboshaft experience all valid)
Proficiency with one of the aero design tools listed above
Familiarity with AM manufacturing constraints for printed metal turbomachinery (IN625 / Inconel preferred; LPBF / FFF process experience valuable)
1D meanline → 3D blade → CAD export workflow