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A prediction method for flow in axial compressors
Thesis (M. Ing.) -- University of Stellenbosch, 1995.
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| Format: | Thesis |
| Language: | en_ZA |
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Stellenbosch : Stellenbosch University
2012
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| _version_ | 1867614119257964544 |
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| access_status_str | Open Access |
| author | Roos, Thomas Helm |
| author2 | Von Backstrom, T. W. |
| author_browse | Roos, Thomas Helm Von Backstrom, T. W. |
| author_facet | Von Backstrom, T. W. Roos, Thomas Helm |
| author_sort | Roos, Thomas Helm |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (M. Ing.) -- University of Stellenbosch, 1995. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/58644 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:46:58.390Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2012 |
| publishDateRange | 2012 |
| publishDateSort | 2012 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/58644 A prediction method for flow in axial compressors Roos, Thomas Helm Von Backstrom, T. W. Stellenbosch University. Faculty of Engineering. Department of Mechanical and Mechatronic Engineering. Compressors Turbomachines Axial flow compressors Reynolds number Air flow Dissertations -- Engineering UCTD Thesis (M. Ing.) -- University of Stellenbosch, 1995. ENGLISH ABSTRACT: A procedure is presented for predicting the flow through axial compressors. The matrix throughflow equation is transformed to yield an expression of radius dependent on stream function and axial position. The solution of the resultant equation combines the advantages of following streamlines through the calculation domain (as in the streamline curvature method, SCM) with the stability of the matrix throughflow method (MTFM), and is correspondingly called the streamline through flow method (STFM). The predictions of the method were compared to analytical results for a number of inviscid test cases and gave good results. As with the SCM and MTFM, using STFM to predict turbomachinery flows requires empirical models for cascade loss and deflection as well as endwall loss. The off-design loss and deflection model of Howell was used as the basis for a new off-design correlation, H2, valid for axial velocity density ratios (AVDR) of unity. The H2 correlation was developed from the NACA 65-Series database as carpet-plotted by Felix. A simple subcritical Reynolds number correlation for loss and deflection was adapted from a method of Roberts, using inlet blade chord Reynolds number, camber angle, pitch-chord ratio, maximum blade thickness-chord ratio and turbulance factor as parameters. The H2 correlation together with the adapted Roberts correlation gave good predictions of loss and deflection for low-Reynolds number cascade flows at AVDR values of unity. Measurements were taken at the compressor inlet and behind each blade row of a low speed, three stage axial flow compressor at three flowrates: near-design, near-surge and near-choke. The predictions of STFM using Howell's endwall loss models, the modified low Reynolds number correlation and respectively Howell's original off design method and H2 were compared with the experimental results. Howell's method predicted pressure rise to within 3% at design and 10% at off-design, compared to 4% at design and 9% at off-design for the H2 method. The prediction of flow angles for H2 were considerably worse than that of Howell. This was deemed to be caused by AVDR effects. An interim AVDR correlation, dependent on stagger angle, was used together with H2. Choosing values of AVDR for the interim correlation which together with H2 would predict flow angles to match the experimental values, predictions of total pressure rise within 3% at design and 8% at off-design were achieved. As a measure of confidence can be placed in H2 and the modified low Reynolds number correlation, the endwall loss correlation of Howell was determined to be the cause of lack of further gains in accuracy. AFRIKAANSE OPSOMMING: 'n Prosedure vir die voorspel van vloei deur aksiaalkompressors word daargestel. Die matriksdeurvloeivergelyking word getransformeer om 'n uitdrukking van radius, wat afhanklik is van stroomfunksie en aksiale posisie, te gee. Die oplossing van die gevolglike vergelyking span die voordele verbonde aan die volg van stroomlyne deur die berekeningsgebied (soos in the stroomlynkrommingsmetode, SKM) met die stabiliteit van die matriksdeurvloeimetode (MDVM), saam. Dienoorkomstig word die prosedure die stroomlyndeurvloeimetode (SDVM) genoem. Die voorspellings van die metode is met analitiese resultate van 'n aantal nie-viskeuse proefgevalle vergelyk en goeie resultate is behaal. Soos met die SKM en MDVM, genoodsaak die gebruik van SDVM om vloei deur turbomasjiene te voorspel empiriese kaskade verlies- en defleksiemodelle, asook wandverliesmodelle. Die af-ontwerp verlies- en defleksiemodel van Howell is as 'n basis gebruik vir 'n nuwe af-ontwerp korrelasie, H2, wat geldig is vir aksiaalsnelheid-digtheidsverhoudings (ASDV) van een. Die H2 korrelasie is vanuit die NACA 65-Reeks databasis soos deur Felix geplot, ontwikkel. 'n Subkritiese Reynoldsgetal korrelasie vir verlies en defleksie is vanuit 'n metode van Roberts aangepas. Hierdie metode maak gebruik van inlaat lemkoord Reynoldsgetal, krommingshoek, lemspasie-koordverhouding, rnaksimum lemdikte-koordverhouding en turbulensiefaktor as parameters. Die H2 korrelasie, saam met die aangepaste Roberts korrelasie, het goeie voorspellings van verlies en defleksie vir lae Reynoldsgetal kaskadevloeie met ASDV waardes van een gegee. Metings is geneem by die kompressorinlaat en agter elke lemry van 'n lae-spoed, driestadium aksiaalvloeikompressor teen drie massavloeie: naby die ontwerppunt, naby die stollyn en naby die wurglyn. Die voorspellings van SDVM met gebruik van Howell se wandverliesmodelle, die gemodifiseerde lae Reynoldsgetal korrelasie en onderskeidelik Howell se oorspronklike af-ontwerp metode en H2, is met die eksperimentele resultate vergelyk. Howell se metode het drukstyging tot binne 3% by ontwerp en 10% by af-ontwerp voorspel, in vergeleke met 4% by ontwerp en 9% by af-ontwerp vir die H2 metode. Die voorspelling van vloeihoeke deur H2 is heelwat swakker as die van Howell. Dit is as gevolg van ASDV-effekte geag. 'n Interim ASDV korrelasie, afhanklik van lemstelhoek, is saam met H2 gebruik. Deur van ASDV-waardes vir die interim korrelasie te kies wat saam met H2 die eksperimentele vloeihoeke sal voorspel, is totale druk voorspellings binne 3% by ontwerp en 8% by af-ontwerp behaal. Aangesien 'n mate van vertroue in H2 en die aangepasde lae Reynoldsgetal korrelasie geplaas kan word, is die wandverlies korrelasie van Howell uitgesonder as die oorsaak van die gebrek aan verdere verbeterings in akkuraatheid. Master 2012-08-27T11:39:04Z 2012-08-27T11:39:04Z 1995 Thesis http://hdl.handle.net/10019.1/58644 en_ZA Stellenbosch University 224 pages : illustrations. application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Compressors Turbomachines Axial flow compressors Reynolds number Air flow Dissertations -- Engineering UCTD Roos, Thomas Helm A prediction method for flow in axial compressors |
| title | A prediction method for flow in axial compressors |
| title_full | A prediction method for flow in axial compressors |
| title_fullStr | A prediction method for flow in axial compressors |
| title_full_unstemmed | A prediction method for flow in axial compressors |
| title_short | A prediction method for flow in axial compressors |
| title_sort | prediction method for flow in axial compressors |
| topic | Compressors Turbomachines Axial flow compressors Reynolds number Air flow Dissertations -- Engineering UCTD |
| url | http://hdl.handle.net/10019.1/58644 |
| work_keys_str_mv | AT roosthomashelm apredictionmethodforflowinaxialcompressors AT roosthomashelm predictionmethodforflowinaxialcompressors |