Abstract The force exerted on the piston of a linear motor driving an orifice pulse tube is analyzed using linearized theory. First, the case of a pulse tube without reservoir is considered. It is found that there are two possible resonances, corresponding to a very small and a very large orifice conductance, respectively. Such resonances can be used to reduce the amplitude of the current provided to the linear motor, and hence to reduce associated ohmic losses. Use of the resonances thus helps to maximize the power delivered to the pulse tube. An expression is derived for the dissipation in the various chambers associated with heat losses to the walls. Experimental results obtained for the amplitude of the piston force indicate that there is a large influence of turbulent effects on thermal diffusivity. The analysis is extended to the case with regenerator. It is found that large temperature ratiosacross the regenerator as well as heat losses to the walls tend to decrease the piston resonance effect.
Piston Resonance in the Orifice Pulse Tube
Cryocoolers 12 ; 265-274
2003-01-01
10 pages
Aufsatz/Kapitel (Buch)
Elektronische Ressource
Englisch
A cross sectional area , C conductance , CA CεD/(2y2) , C ε see Eq. (2) , c specific heat , COo Co/Cr , CO r see Eq. (39) , D distance between parallel plates , F force , G (γ — 1)SD/(4V) , $$\dot m$$ mass flow rate , P o average pressure , Greek Symbols , $$\bar \alpha$$ thermal diffusivity, k/(pc p ) , Δ denotes amplitude , δ phase angle , γ ratio of specific heats , λ characteristic thermal boundary layer thickness, $$(2\bar \alpha /\omega )^{{1 \mathord{\left/{\vphantom {1 2}} \right.\kern-\nulldelimiterspace} 2}}$$ , πb Δpb/Δpp , πp Δpp/Δpd , ρ density , Ω frequency, see Eqs.16, 22 and 36 , ω angular frequency , p pressure , $$\dot Q$$ rate of heat flow into system , $$\dot q$$ heat flux into wall , S surface area , s 2x/(D) , T temperature , t time , U internal energy , V volume , $$\dot W$$ rate of work done by system , x distance from center plane; also piston displacement , y (D)/(2λ) , z (1+i)y , Subscripts , b buffer (reservoir) , c cold , d driver , h hot , o orifice; average , p pulse tube , r regenerator , w wall Physics , Condensed Matter Physics , Automotive Engineering , Mechanics , Thermodynamics
Piston Resonance in the Orifice Pulse Tube
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