Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
Effect of permanent disk skew on rotor vibration and its relationship with manufacturing tolerances
Thesis (MEng) -- Stellenbosch University, 2023.
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | en_ZA |
| Published: |
Stellenbosch : Stellenbosch University
2023
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867614025310797824 |
|---|---|
| access_status_str | Open Access |
| author | Du Toit, T. H. J. |
| author2 | Els, D. N. J. |
| author_browse | Du Toit, T. H. J. Els, D. N. J. |
| author_facet | Els, D. N. J. Du Toit, T. H. J. |
| author_sort | Du Toit, T. H. J. |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MEng) -- Stellenbosch University, 2023. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/127091 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:45:28.762Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2023 |
| publishDateRange | 2023 |
| publishDateSort | 2023 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/127091 Effect of permanent disk skew on rotor vibration and its relationship with manufacturing tolerances Du Toit, T. H. J. Els, D. N. J. Van der Westhuizen, K. Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering. Rotors -- Vibration Rotors (Helicopters) -- Aerodynamics Vibration (Aeronautics) Computer-aided design UCTD Thesis (MEng) -- Stellenbosch University, 2023. ENGLISH SUMMARY: The purpose of this study is to investigate the relationship between permanent disk skew and manufacturing tolerances for overhung rotors typically found in small turbojet engines. Static unbalance is a well-known and well-understood load type that is incorporated in modern rotordynamics software. However permanent disk skew is not as widely discussed and not a typical load type option for finite element analysis. The relationship between manufacturing tolerances and the effects that disk skew has on rotordynamics was investigated. A disk skew load equation is formulated from first principles with units that are compatible with finite element models within the ANSYS environment. Three disk skew angles were tested on a turbojet engine spool and overhung dummy impeller. Disk skew was controlled by a tapered spacer mounted between the impeller and bearing race on the shaft. Minor axial runouts on the spacer (measuring between 20 μm and 60 μm) resulted in disk skew angles of between 0.045° and 0.225° which caused vibration amplitudes to increase significantly. The calibrated finite element model correlated very well with the test results and was also used to investigate the impact of disk skew at higher speeds. Disk skew was shown to particularly influence bending modes. It was concluded that the disk skew angle is very sensitive to small changes in manufacturing tolerances, and this has a significant impact on vibration. The dimensionless amplitude factors increase almost linearly with the disk skew angle. Instead of trying to manufacture extremely small tolerances, 2-plane balancing for the impeller’s dynamic unbalance is the most economical solution. AFRIKAANSE OPSOMMING: Die doel van hierdie studie is om die verband tussen permanente skyskeef en vervaardigingstoleransies vir oorhangrotors wat tipies in klein turbostraalenjins voorkom, te ondersoek. Statiese onbalans is ’n wel-bekende tipe rotorlas wat in moderne rotordinamikasagteware ingesluit word. ‘n Minder algemene/bekende rotorlas, wat nie 'n tipiese soort lasopsie vir eindige element-analise nie, is permanente skyfskeefheid (‘disk skew’). Die lasvergelyking vir skyfskeefheid word vanuit eerste beginsels geformuleer, met eenhede wat met eindige elementmodelle in ANSYS versoenbaar is. Drie skyfskeefheidshoeke van ‘n turbostraalenjin-spoel se oorhangende fop-dryfwaaier is geanaliseer en getoets. Skyfskeefheid is noukeurig beheer deur 'n tapse spasieerder wat tussen die dryfrat en die laerring op die as gemonteer is. Geringe aksiale variasie op die buitediameter van die spasieerder is gemeet (op die omtrek gemeet soos die as draai) – tussen 20 μm en 60 μm – en het gelei tot skyfskeefheidshoeke van 0.045° tot 0.225°. Hierdie toename het ‘n beduidende effek op vibrasie-amplitudes. Die gekalibreerde eindige element model korreleer baie goed met die toetsresultate en is gebruik om die impak van skyfskeefheid teen hoer snelhede te ondersoek. Daar is getoon dat buigmodusse, by uitstek, deur skyfskeefheid beinvloed word. Die gevolgtrekking is dat die skewe hoek van die skyf (soos gemeet relatief tot ‘n haaks skyf) baie sensitief op klein veranderinge in vervaardigingstoleransies reageer, en dit het 'n beduidende impak op vibrasie. Nie-dimensionele amplitudefaktore neem byna lineer toe met ‘n toename in skyfskeefheidshoek. Die mees ekonomiese oplossing tot die uitskakeling van dinamiese wanbalans, is 2-vlak balansering vir die dryfrat eerder as om tot uiters klein toleransies te probeer vervaardig. Masters 2023-03-02T08:18:48Z 2023-05-18T07:03:51Z 2023-03-02T08:18:48Z 2023-05-18T07:03:51Z 2023-03 Thesis http://hdl.handle.net/10019.1/127091 en_ZA Stellenbosch University xvii, 89 pages : illustrations, includes annexures application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Rotors -- Vibration Rotors (Helicopters) -- Aerodynamics Vibration (Aeronautics) Computer-aided design UCTD Du Toit, T. H. J. Effect of permanent disk skew on rotor vibration and its relationship with manufacturing tolerances |
| title | Effect of permanent disk skew on rotor vibration and its relationship with manufacturing tolerances |
| title_full | Effect of permanent disk skew on rotor vibration and its relationship with manufacturing tolerances |
| title_fullStr | Effect of permanent disk skew on rotor vibration and its relationship with manufacturing tolerances |
| title_full_unstemmed | Effect of permanent disk skew on rotor vibration and its relationship with manufacturing tolerances |
| title_short | Effect of permanent disk skew on rotor vibration and its relationship with manufacturing tolerances |
| title_sort | effect of permanent disk skew on rotor vibration and its relationship with manufacturing tolerances |
| topic | Rotors -- Vibration Rotors (Helicopters) -- Aerodynamics Vibration (Aeronautics) Computer-aided design UCTD |
| url | http://hdl.handle.net/10019.1/127091 |
| work_keys_str_mv | AT dutoitthj effectofpermanentdiskskewonrotorvibrationanditsrelationshipwithmanufacturingtolerances |