A Study of an Integrated Analysis Model with Secondary Flow for Assessing the Performance of a Micro Turbojet Engine
Abstract
:1. Introduction
2. Methodology
2.1. Engine Model
2.2. Integrated Analysis Model
2.2.1. Domain and Grid
2.2.2. Solver Setting
- Frozen rotor interface w/ secondary air flow [21].
- Mixing plane w/ secondary air flow.
2.3. Power Matching
2.4. Combustion Efficiency
2.5. Secondary Air Flow
3. CFD Results
3.1. Compressor
3.2. Combustor
3.3. Turbine
4. CFD Validation and Discussion
4.1. Test Facility
4.2. Engine Performances Validation at Sea-Level Conditions
4.3. Engine Performances Validation at Altitude Conditions
5. Conclusions
- Due to the high rotational speed and small size of micro gas turbines, the interface setting between the impeller and diffuser is important, and a mixing plane interface with secondary air flow is a suitable option.
- Based on previous studies, a combustion efficiency of 90% was reflected, and in the case of secondary air flow, a 3% air flow rate was designated for bleeding in and out at the impeller and turbine rotor, respectively.
- Compared with test data, most engine performances, such as air flow rate, pressure ratio, and thrust, are within 5% of the test values, indicating that the engine performance is predicted well.
- Among the engine performances, EGT exhibits a relatively large error of over 10%. However, this discrepancy is exclusive to low-RPM regions and attributed to the differences between test values obtained at a single point and CFD results that employ an average temperature at the plane. So, there was no issue with the EGT.
- Due to the fuel-lubricated system, a test result of the fuel flow rate includes the combustion fuel flow rate and the lubricated flow rate. In contrast, the analysis model excluded the lubricated flow rate. Therefore, the lubrication system exerts an influence on the fuel flow rate and TSFC. Upon correcting the flow rate utilized for lubrication, it was confirmed that the error was reduced.
- The analysis was performed using the same 3% bleed mass flow rate condition for all cases. The results demonstrated that the bleed flow rate should be adjusted according to RPM and that the fuel flow rate tended to increase as the secondary air flow increased.
Author Contributions
Funding
Data Availability Statement
Conflicts of Interest
Nomenclature
N | Shaft Rotating Speed [RPM] |
TSFC | Thrust-Specific Fuel Consumption [kg/h-N] |
Fn | Thrust [N] |
EGT | Exhaust Gas Temperature [K] |
PR | Compressor Pressure Ratio |
Wf | Fuel Flow Rate [g/s] |
Wa | Air Flow Rate [kg/s] |
RF | Relaxation Factor |
Greek symbol | |
τ | Torque [Nm] |
Δ | Normalized Pressure |
Θ | Normalized Temperature |
Subscripts | |
Comp | Compressor |
Turb | Turbine |
SLS | Sea Level Standard |
* | Corrected Value |
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Parameters | Properties | Unit |
---|---|---|
Idle RPM | 35,000 | RPM |
Max. RPM | 106,000 | RPM |
Thrust @ Idle RPM | 14 | N |
Thrust @ Max. RPM | 300 | N |
Pressure Ratio | 3.55 | - |
Mass flow rate (Air) | 0.5 | kg/s |
Fuel Consumption @ Idle RPM | 179 | mL/min |
Fuel Consumption @ Max. RPM | 980 | mL/min |
Weight | 2630 | g |
Diameter | 132 | mm |
Length (Incl. Start motor) | 365 | mm |
Component | Sector | # of Elements |
---|---|---|
Entry | 360/7° | 821,614 |
Impeller | 360/7° | 3,007,260 |
Diffuser | 360/15° | 961,150 |
Combustor | 360/12° | 3,847,684 |
Turbine stator | 360/21° | 1,007,880 |
Turbine rotor | 360/29° | 1,082,720 |
Nozzle | 360/6° | 3,804,753 |
Total | - | 14,533,061 |
No. | Inlet Pressure [kPa] | Inlet Temperature [K] | Simulating Altitude |
---|---|---|---|
1 | 101.325 | 288.15 | 0.0 km (Sea level) |
2 | 94.3 | 300.7 | 0.6 km |
3 | 84 | 298.9 | 1.5 km |
4 | 69.7 | 298.2 | 3.0 km |
ANSYS, Inc. | ||
CFD Solver | CFX_2020_R2 | |
Analysis Type | Steady State | |
Turbulence Model | SST Model with Reattach Modification | |
Combustion Model | Eddy Dissipation Model (EDM) | |
Interface | Impeller-Diffuser | 1. Frozen Rotor w/o Secondary air flow |
2. Mixing Plane w/ Secondary air flow | ||
Rest of all | Mixing Plane |
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Lee, D.; Chung, H.; Kang, Y.S.; Rhee, D.-H. A Study of an Integrated Analysis Model with Secondary Flow for Assessing the Performance of a Micro Turbojet Engine. Appl. Sci. 2024, 14, 7606. https://doi.org/10.3390/app14177606
Lee D, Chung H, Kang YS, Rhee D-H. A Study of an Integrated Analysis Model with Secondary Flow for Assessing the Performance of a Micro Turbojet Engine. Applied Sciences. 2024; 14(17):7606. https://doi.org/10.3390/app14177606
Chicago/Turabian StyleLee, DongEun, Heeyoon Chung, Young Seok Kang, and Dong-Ho Rhee. 2024. "A Study of an Integrated Analysis Model with Secondary Flow for Assessing the Performance of a Micro Turbojet Engine" Applied Sciences 14, no. 17: 7606. https://doi.org/10.3390/app14177606