Turbojet Engine Design

Translate a 1–5 kN application statement into measurable thrust, flight-envelope, size, mass, life, cost, and safety requirements for the three engine studies.

Define a consistent station-numbering system and control volumes for a single-spool turbojet flow path.

Convert between static and stagnation properties for a calorically imperfect compressible gas.

Calculate mass-flow parameter, choking, area–Mach relations, and normal-shock pressure loss in quasi-one-dimensional passages.

Apply mass conservation and the steady-flow energy equation to an individual turbojet component.

Calculate isentropic, polytropic, combustion, and mechanical efficiencies from component station data.

Derive ideal Brayton-cycle state changes from compressor pressure ratio and turbine-inlet temperature.

Calculate gross thrust, ram drag, pressure thrust, net thrust, and specific fuel consumption from a control-volume momentum balance.

Implement and validate temperature-dependent air and combustion-gas property functions in GNU Octave.

Calculate the compressor-inlet state from flight condition, inlet area, and intake pressure recovery.

Implement compressor outlet temperature, shaft-work, and corrected-flow calculations in Octave.

Determine combustor fuel–air ratio from an energy balance and specified turbine-inlet temperature.

Solve the turbine work balance including mechanical loss, secondary-air extraction, and accessory power.

Determine nozzle choking, exit conditions, effective velocity, and thrust for convergent and convergent–divergent nozzles.

Assemble a design-point turbojet cycle solver and verify its station-by-station mass and energy balances.

Perform a parametric sweep to select pressure ratio, turbine-inlet temperature, mass flow, and nozzle area for each compressor architecture.

Construct rotor and stator velocity triangles for an axial-compressor stage.

Calculate stage work, total-pressure rise, and degree of reaction using Euler’s turbomachinery equation.

Select flow and loading coefficients subject to tip-Mach-number, de Haller, and diffusion-factor limits.

Select a preliminary spool speed, determine stage count, and distribute compressor work across the stages.

Size hub, mean, and tip radii along the compressor annulus while satisfying continuity and blade-height limits.

Calculate spanwise flow angles using radial equilibrium and a selected vortex law.

Estimate blade-row loss, blockage, deviation, and stage efficiency with preliminary correlations.

Implement and verify a multistage axial-compressor meanline model in Octave for the all-axial engine baseline.

Calculate incidence and deviation to convert axial-compressor flow angles into blade metal angles.

Select chord, solidity, aspect ratio, and leading- and trailing-edge dimensions from cascade operating limits.

Construct a three-dimensional representative blade row by stacking hub, midspan, and tip sections derived from the meanline design.

Quantify the effects of rotor tip clearance and endwall blockage on compressor pressure ratio and efficiency.

Generate a quality-controlled structured blade-passage mesh in ANSYS TurboGrid.

Configure and converge a periodic axial-compressor stage simulation in ANSYS CFX.

Generate corrected-speed performance lines and identify choke, peak-efficiency, and numerical-stall boundaries.

Calibrate the Octave meanline model against CFD by updating loss, blockage, and deviation parameters without overfitting.

Construct centrifugal-impeller inducer velocity triangles and select hub, shroud, and eye radii subject to incidence and Mach-number limits.

Determine impeller tip diameter and rotational speed from Euler work, backsweep, and slip-adjusted pressure rise.

Define the impeller meridional passage, blade-angle distribution, throat area, and main- and splitter-blade arrangement.

Estimate incidence, slip, skin-friction, disk-friction, leakage, and passage losses for a centrifugal impeller.

Design a vaneless or vaned diffuser for the required pressure recovery, diffusion rate, and operating range.

Design an axisymmetric deswirl passage and diffuser-exit transition that supplies an annular combustor with acceptable distortion.

Implement a centrifugal-compressor meanline model and generate a preliminary corrected performance map in Octave.

Configure an impeller–diffuser CFX model and use its results to calibrate the preliminary slip and loss assumptions.

Allocate the overall compressor pressure ratio between the axial booster and centrifugal stage using efficiency, diameter, and stability constraints.

Select compatible corrected mass flow and rotational speed for the two compressor sections on a common shaft.

Produce the axial-booster meanline design by applying the established axial-stage workflow.

Size the interstage transition duct subject to area-change, diffusion, boundary-layer, and blockage limits.

Match booster-exit swirl, velocity profile, and tip clearance to centrifugal-inducer requirements.

Construct a combined axial–centrifugal compressor map by enforcing common shaft speed, mass flow, and interstage losses.

Evaluate booster-to-impeller flow nonuniformity with an interface CFD model and quantify its effect on impeller incidence.

Compare the three compressor architectures against common requirements and freeze a traceable preliminary baseline for each engine.

Derive combustor airflow, heat-release, pressure-loss, stability, durability, and exit-temperature requirements for each engine baseline.

Size the pre-diffuser, dump region, casing annulus, and liner reference area.

Allocate combustor air among primary, intermediate, dilution, and liner-cooling zones.

Determine primary-zone volume from loading, residence-time, equivalence-ratio, and stability constraints.

Size a preliminary fuel-delivery circuit, including pump pressure, manifold flow, injector effective area, and characteristic droplet size.

Size liner primary, dilution, and cooling holes from discharge, jet-penetration, and pressure-drop requirements.

Predict combustion efficiency, total-pressure loss, outlet pattern factor, lean-blowout margin, and altitude-relight margin with preliminary correlations.

Configure a reacting-flow sector model and interpret recirculation, flame location, pressure loss, and turbine-inlet temperature distribution.

Determine turbine work, pressure ratio, cooling-flow allowance, and stage count for each engine baseline from its spool power balance.

Construct turbine stator and rotor velocity triangles for selected loading, reaction, and exit-swirl targets.

Size turbine mean radius, annulus dimensions, and rotational speed limits for the required mass flow.

Construct preliminary spanwise vane and rotor geometry from radial-equilibrium angles, throat capacity, and Zweifel-loading constraints.

Estimate turbine profile, secondary-flow, tip-clearance, trailing-edge, and exit-kinetic-energy losses.

Construct representative three-dimensional vane and rotor geometry and generate structured passage meshes in ANSYS TurboGrid.

Configure and converge a periodic turbine-stage simulation in ANSYS CFX.

Reconcile CFX flow capacity, work, and efficiency with the meanline model and document the resulting correlation updates.

Draw a node-and-branch secondary-air network identifying candidate bleed extraction, cavity, seal, cooling, and reinjection locations.

Solve the secondary-air network in Octave from pressure boundary conditions, restriction areas, discharge coefficients, and rotating-cavity effects.

Select and size preliminary labyrinth or brush seals for shaft, disk-cavity, and bearing-chamber leakage control.

Determine disk-cavity purge flow, ingestion margin, and windage power using preliminary correlations.

Estimate gas-side heat-transfer coefficients, heat flux, and uncooled metal temperatures for turbine vanes, blades, and disks.

Size preliminary internal-convection and film-cooling flows to meet specified metal-temperature and coolant-pressure limits.

Recalculate cycle performance and turbine efficiency after accounting for bleed extraction, seal leakage, coolant pumping, and mainstream mixing.

Size preliminary lubrication, scavenge, breather, and oil-cooling flows from bearing and gearbox heat loads.

Screen candidate compressor, combustor, turbine, shaft, bearing, and casing materials against temperature, strength, oxidation, creep, fatigue, and manufacturing requirements.

Define the rotor-support architecture and calculate bearing reactions from component weights, aerodynamic loads, thrust imbalance, and maneuver loads.

Select bearing type and size from load, speed, lubrication, temperature, stiffness, and preliminary life requirements.

Size the main shaft from torque, combined bending, stiffness, stress concentration, overspeed, and accessory-drive constraints.

Estimate turbine-disk stress, overspeed burst margin, and preliminary low-cycle-fatigue usage with a rotating-disk model.

Calculate blade centrifugal and root-attachment stresses, estimate first natural frequencies with centrifugal stiffening, and check engine-order separation.

Construct a lumped rotor–bearing model and Campbell diagram to identify rigid-body and bending critical-speed margins.

Calculate cold-build axial and radial clearances from thermal growth, centrifugal growth, casing movement, bearing motion, and tolerance stack-up.

Size a subsonic intake and diffuser, then quantify pressure recovery and flow distortion across the intended flight envelope.

Size the exhaust duct and propelling nozzle for design-point and off-design operation.

Scale compressor and turbine maps using corrected variables, flow-capacity corrections, and similarity parameters.

Solve the steady-state compressor–turbine–nozzle matching equations at a specified off-design condition.

Trace the compressor operating line and calculate surge margin across the flight and power envelope.

Calculate starter torque and simulate spool acceleration from rest to self-sustaining and idle speeds using rotor inertia and component torques.

Construct start, acceleration, deceleration, and steady-running fuel schedules with ignition, temperature, speed, flameout, and surge limits.

Construct a top-level CAD master skeleton defining the gas path, rotor, casing, mounts, accessory drive, starter, fuel, oil, electrical, and service interfaces.

Select feasible manufacturing routes for blades, impellers, disks, shafts, combustor liners, casings, and ducts.

Determine functional fit classes and surface-finish specifications for bearing seats, seals, shaft interfaces, blade attachments, and casing joints.

Apply GD&T controls, including datum systems, runout, position, and profile tolerances, to critical rotating and gas-path parts.

Create an assembly and quality plan with dimensional inspection, nondestructive examination, traceability, rotor balancing, and release hold points.

Define preliminary engine rotor-containment requirements and test-cell fire protection, ventilation, fuel isolation, interlocks, and emergency shutdown provisions.

Select thrust, pressure, temperature, speed, vibration, emissions, and fuel-flow instrumentation and calculate measurement uncertainty.

Construct a staged cold-check, cranking, light-off, commissioning, and performance-test matrix with operating limits and abort criteria.

Apply a gated requirements, interface, risk, and configuration review to close the all-axial, centrifugal, and axial–centrifugal design packages.