Performance testing of an axial flow fan in an A-frame test facility

Van Eck, Johannes (2019-04)

Thesis (MEng)--Stellenbosch University, 2019.

Thesis

ENGLISH ABSTRACT: The primary objective of this research and experimental investigation is to determine the performance of an axial flow fan in an A-frame test facility. Commissioning of the A-frame test facility required certain modifications which allowed the facility to be used for testing purposes. Modifications include a new fan drive system, fan bridge, heat exchanger and structural supports. The bell mouth roundness was improved upon, achieving a more constant tip clearance around the casing, and all air leaks around the facility were sealed to prevent loss of mass flow. Tests were conducted on the B2-fan, according to standardised fan testing procedures in ISO 5801 (2007) Type-A, to obtain the fan characteristics at selected blade angles. The measurements recorded at the A-frame test facility included outlet velocity, inlet velocity, fan torque and rotational speed measurements. The outlet velocity profiles differ for the two heat exchanger outlets, but the total volumetric flow rate differs only by 3% for the two sides. It was also found that the velocity profile stays similar with a change in blade angle, but increases in magnitude as the blade angle is increased. Pressure measurements according to ISO 5802 (2008), at the walls of the plenum chamber, were regarded as unusable due to it being much lower than the expected pressure. With the use of the system draft equation from Kröger (2004, 8.1.30) it was possible to calculate a recovery coefficient for the A-frame plenum chamber at different blade angle settings of the B2-fan, with values of 0.505, 0.685 and 0.412 for the 28º, 31º and 34º blade angles respectively. The recovery coefficient calculated for the M-fan equalled 0.143 and 0.322 for the 34º and 35º blade angles respectively. This value represents the portion of kinetic energy that is converted back into a pressure. The sensitivity of the recovery coefficient to change in volumetric flow rate and heat exchanger loss coefficient was also investigated with the use of a Monte Carlo simulation. The importance of accurately measuring the volumetric flow rate is shown by a normal distribution of the recovery value with the use of the mean and standard deviation of the volumetric flow rate. A functional A-frame test facility can now be used to test different heat exchanger and fan configurations. By changing the fan, heat exchanger type or area, the performance of the A-frame setup can be analysed for various heat exchanger and fan configurations.

AFRIKAANSE OPSOMMING: Die primêre doelwit van hierdie navorsing en experimentele ondersoek is om die werking van ‘n aksiaal waaier binne ‘n A-raam toets fasiliteit te bepaal. Die ingebruikstelling van die A-raam toetsfasiliteit het sekere aanpassings benodig wat die fasiliteit bruikbaar vir toets doeleindes gestel het. Aanpassings sluit ‘n nuwe waaier aandryfstelsel, waaier brug, warmte uitruiler en strukturele versterkings in. Die klokmond inlaat se rondheid is verbeter wat daartoe gelei het dat ‘n meer konstante waaier lempunt spasiëring binne die omhulsel bereik is. Verder is alle lekplekke verseel sodat daar geen massavloei verlore gaan nie. Toetse is gedoen op die B2-waaier volgens die standard waaier toets prosedures soos in ISO 5801 (2007) Tipe A om die waaier karakteristieke by sekere lem hoeke te verkry. Die metings wat by die A-raam fasilitiet geneem is sluit die uitlaat snelheid, inlaat snelheid, waaier wringkrag en die waaier omwentelingspoed in. Die uitlaat snelheidsprofiel verskil vir die twee warmte-uitruilers, maar die totale volumetriese vloeitempo tussen die twee kante slegs met 3%. Die snelheidsprofiel bly naastenby dieselfde vir verskillende lemhoeke en verander slegs met ‘n konstante waarde regoor die profiel, Druklesings is ook geneem in die vier mure volgens ISO 5802 (2008), maar die resultate daarvan as nutteloos beskou weens dit heeltemal te lae resultate gegee het. Deur gebruik te maak van die sisteem vloei vergelyking, vanaf Kröger (2004, 8.1.30), is die druk herwinningskoëffisiënt vir die B2-waaier in die A-raam opstelling bereken om 0.505, 0.685 en 0.412 vir die 28º, 31º and 34º lemhoeke respektiewelik te wees. Die herwinningskoëffisiënt vir die M-waaier is bereken om 0.143 en 0.322 vir die 34º en 35º lemhoeke respektiewelik te wees. Hierdie koëffisiënt word gebruik om die gedeelte kinetiese energie wat in druk omgeskakel word binne die plenum kamer te beskryf. Die sensitiwiteit van hierdie koëffisiënt vir verandering in die volumetriese vloeitempo en warmte uitruiler druk verlies koëffisiënt is ook bereken deur gebruik te maak van die Monte Carlo metode. Die belangrikheid van akkurate metings om die volumetriese vloeitempo te bereken word duidelik gemaak deur die normaal verspreiding van die herwinnings koëffisiënt deur gebruik te maak van die gemiddelde en standaardafwyking van die volumetriese vloeitempo. ‘n Funsionele A-raam toetsfasiliteit kan nou gebruik word om verskillende warmte uitruiler en waaier samestellings mee te toets. Deur die waaier, tipe warmte uitruiler of die area van die warmte uitruiler te verander, kan die A-raam opstelling getoets word vir verskillende warmte uitruiler en waaier opstelling senarios.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/106233
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