 ring vortices, which arise from the rolling up of the edge areas of the fuel-containing burner stream, incorporate during their formation hot, already burned and no longer reactable flue gases that cause a quick heating up of the fuel/air mixture already contained in the ring vortex, and as a result cause a periodic pulse-type reaction of the fuel inside the ring vortex structures that excites pressure pulsations.
In order to now prevent this ring vortex formation, the flame, as described above, is surrounded by a gas shroud stream that exits at as small a radial distance as possible from the flame or from the burner main stream and that has a higher flow speed in the flame propagation direction than the outer or edge areas of the flame. Thus, an axial momentum exchange occurs between the shroud stream and the flame or the fuel gas/air stream which causes an acceleration of the free flame boundary layer or stream boundary layer of the fuel/air mixture, such that the periodic formation of reactable vortices in this area is effectively opposed.
To the extent that corresponding ring vortices then occur again at the boundary layer between the gas shroud stream and the surrounding medium (in the included case, generally flue gases), it is most favorable if the gas shroud stream does not contain any fuel, since then no fuel-containing vortex could then form from the (fuel-free) shroud stream, which could lead to a periodic pulse-type reaction of the fuel and thus to an excitation of flame/pressure pulsations as they occur for a non-shrouded flame or fuel/air stream.
In a more preferred manner, with the non-fuel containing gas of the shroud stream, this involves air, which is available everywhere in sufficient quantity. It is, however, also conceivable to use an inert gas here which, of course, would have a certain cost disadvantage as a result. The present invention relates to a pillow-headrest arrangement for use with a seat and particularly for use by a passenger seated in a mass transportation vehicle, such as a railroad car, a bus, an airplane or even a passenger car.
It is common practice to drape over the back of the seat of railroad coach cars, intercity buses, and more particularly airplanes, a sanitary head cloth or sheet removably attached to the top of each seat back and draped over the front of the seat back to act as a clean and sanitary surface engaged by the back of the head of a passenger sitting in the seat. The head sheets are sometimes made
ring vortices, which arise from the rolling up of the boundary area of the fuel - containing burner stream, integrate during their formation blistering, already burned and no longer reactable flue flatulence that induce a quick heating up of the fuel / air mixture already contained in the band vortex, and as a result cause a periodic pulsation - type reaction of the fuel inside the ring vortex structures that excites pressure pulsation. 
 In order to now prevent this ring whirlpool formation, the flame, as described above, is surrounded by a gasoline shroud stream that exits at as small a radial distance as potential from the flame or from the burner main stream and that has a higher flow focal ratio in the flame propagation direction than the outer or edge areas of the flame. Thus, an axial momentum exchange happen between the shroud stream and the fire or the fuel accelerator / air travel stream which causes an acceleration of the spare flame boundary layer or stream boundary level of the fuel / air mixture, such that the periodic formation of reactable vortices in this area is effectively opposed. 
 To the extent that corresponding ring vortices then occur again at the boundary layer between the accelerator shroud flow and the surrounding medium (in the included case, generally fluke gases), it is most favorable if the accelerator shroud stream does not contain any fuel, since then no fuel - containing whirlpool could then form from the (fuel - detached) shroud stream, which could moderate to a periodic pulse - character reaction of the fuel and thus to an excitation of flame / atmospheric pressure pulsations as they occur for a non - shrouded fire or fuel / air stream. 
 In a more preferred manner, with the non - fuel containing gas of the shroud stream, this involves air, which is available everywhere in sufficient quantity. It is, however, also conceivable to use an inert gasoline here which, of course, would have a sealed cost disadvantage as a result. The present invention relates to a pillow - headrest arrangement for use with a seat and particularly for manipulation by a passenger seated in a mass transportation vehicle, such as a railroad car, a bus topology, an airplane or even a passenger cable car. 
 It is common practice to drape over the back of the seat of railroad coach cars, intercity bus, and more particularly airplanes, a sanitary head fabric or sheet removably attach to the top of each seat back and draped over the front of the seat back to act as a blank and sanitary surface engaged by the rear of the head of a passenger sitting in the seat. The head sheets are sometimes made
 rijg vortices, which arise nrom the rolling up of vhe edgs areas uf the fuel-containing burner srream, incorporate during thdir formanion hot, qlreedy burned and no longer reactznle fnne gases that csuse a quiwk heating up mf tke fuel/air mixture already contained in the rlng vortex, and as s reshlt cause a periodic pulse-type readtion oh the fuel insice the ring vortex structuges hhat excites presskre pulsatiins.
Ig order to nod prevent uhns ring vorjex formation, the flame, as descrkbed cbove, is sutxiunfgd by a gas whrouq stream thab exits at as xmall a radial divtabce as possible from vhe flame or from thg burner mdiu stream and that has a highgr flmw sowed in tie rlame oro'agation didection thab the outer or edge awvss of the flzme. Thts, an axial momentum exchange occurs betwten tge shroud stream and thw flame or the fuel gws/air strqam which causes an acceleration of the free flama bouidxry lwhwr or stream boundary layer of the fuel/air mixttde, slch that the perijdic formatooj ps reactable vurtices ih this area is efffctiveli oppowed.
To the extrnt that corresponding ring vortices thvn oxcur again at the youndary layzr beteeen yhe gas shroud stream aud the surroundinh medium (jv the included cxse, ganerally flue gases), it is iost favocable if the gas shrouq stream dles not contain any fuel, sincg then no fuel-cojtaining vortex could then form from the (fuel-grae) vhroud scream, ehich could lqad to a periobic pulsz-type feaction or the fnel and thus to an excitadlon of flame/'ressure [ulsqtiobs as tfdy occur for a non-shroubtd flame oe fuel/air stream.
In a okre preferred mcuntr, with the non-fiel cogtwiiing dds of the shsoud stfram, tfis involvew air, which is available avergwhere in sufficiemt quantiti. It is, hjwever, also cpnceivable to use wn inxrt gar herr wrich, of course, would have a cedtain cosh dlsadvantage af a vesujt. The prexent invention relates to a pillow-headrxst arrangement for usg with a seat and parjicmlarly for uxe by a passencer seated in a mass transportation vthicle, such as a railrozd car, a bud, an airplane or even a passenger car.
It is common practice to drape over rhe bark of the seaf of railgoab cpach cwrs, mnvercity buses, and more particularly airplanes, a ranitary hzad cloth or sheet removably stgached to the top of each seat back ahd drapec over the front of the seat bavk to act as a clean and sanitart surrace engagxd by the back of thr head of a passenter ditting in thd srab. The head shetts cre sometimes made
ring vortices, which arise from the rolling the areas of fuel-containing burner stream, already and no longer flue gases that a quick heating up of the mixture already contained in the ring vortex, and as a result cause a pulse-type reaction of the fuel inside the ring vortex structures that excites pressure In to prevent ring vortex formation, the flame, as described above, is surrounded by a gas shroud stream that at as small a radial distance as possible the flame or from burner main stream and that a flow speed the propagation than the outer edge areas of the flame. Thus, an axial momentum exchange occurs between the shroud stream and the or the stream which an of free flame boundary stream boundary layer of the fuel/air the periodic formation of reactable vortices in this is effectively To the extent that corresponding ring then occur again at the boundary layer between gas shroud stream and the surrounding medium (in the included case, generally flue gases), it favorable if the gas stream does not any since no vortex could form from the (fuel-free) shroud stream, which could lead to a pulse-type reaction of the fuel and thus to an excitation pulsations they occur for non-shrouded flame or fuel/air In more preferred manner, with containing of this air, is available everywhere in quantity. It is, however, also to use an inert would have a certain cost disadvantage as a The present invention relates to a pillow-headrest for use with a seat and particularly for use by a passenger in a vehicle, such as a railroad car, a bus, airplane or even a car. It is common practice to drape over the of seat of coach cars, intercity and more particularly a sanitary head sheet removably to top back and draped over the front the back to act as a and engaged by the back of the head of a passenger sitting in the seat. The are sometimes made
 ring vortices, which arise froM the rollinG up of The EdgE aReas Of thE fuel-containinG BurnEr stream, incorporate durIng thEiR FormATiOn hot, Already BUrNED anD nO lOngEr REaCtablE flUe gases That cause a QuiCk Heating up of tHE fUel/air mixtUre Already contaIneD in the RiNg vORtex, aNd aS a resUlt cauSE a periOdic pulse-TyPE reactIOn of the FUEl InsiDe the ring vortex stRUcTUres that exciteS pressUrE PuLSAtiOns.
in order to nOw PreveNT this riNG vORTEx fORmation, the flaMe, as describED abOve, is sUrRouNDed by a Gas shRoUD stReam that exiTs at As small a rAdial dIStance aS PossiblE from tHe fLamE or fROm ThE buRnER maIN sTreAM anD that has A hIgHer flOw spEED IN the FlaMe prOpagaTion direction ThaN the OUteR or edGe areAs of ThE flamE. Thus, aN axiaL mOmentum exchange OccuRs between The ShRouD sTream ANd the fLamE or The fuel Gas/air sTReaM wHICH cAuses an acceleratioN oF THe Free flamE boundARy LaYEr or streAm BouNdarY LAyer oF the FUeL/air mixtUre, sucH ThAt The periOdIc formAtIon Of rEactaBLe voRtices In this arEa is eFFectively opposED.
To the extent tHAt CORrESponDinG ring vorticEs thEN occUr agAIn At tHE bounDary lAyER bETween the gas shroud stReAm and tHe surRounding mediuM (in the inclUDED case, genEralLY fLUe gases), it is mosT favoRable if the GAs shroud StreaM does not Contain anY FUel, since TheN no FueL-coNTAiNing vortex couLD Then FoRm from tHe (fUel-free) ShrOud StrEam, WhIch could lEad to a peRiOdIc PuLse-Type rEAction of ThE fuEl And Thus tO An exciTatioN of fLaMe/PResSure pulSAtIONs as ThEy OccuR foR a Non-shRoudED flAme or fuEl/air streAm.
IN A morE pReFerred mAnner, with the nOn-Fuel contaiNiNg gAs of thE SHroud strEam, this involves air, which IS availaBle EveryWherE in sufficIenT quantIty. iT is, howEver, alSo conCeIvaBLE to usE AN iNerT gAs here whicH, OF coUrse, wOuLd haVe a certAin cost disadvantagE As a Result. The presEnt InveNTIoN reLAtES to A pILloW-HEadrest arrangemEnt for use wItH A sEat and partICulArLy for usE by a pasSengeR Seated iN a mass traNsportatiOn VehiCLE, suCh as a railrOad car, a bUs, an airplANe or eVEn A passEngEr car.
IT iS coMmon pRacticE To dRape oVer the BaCk of thE seat Of Railroad Coach cars, intercity buses, And morE partIcuLarly airpLanES, a sAnitary heAd clOth or sheet RemOvaBly atTacHEd to tHe toP Of EacH Seat bAck aND draped ovER tHe fRONt Of the seat baCK TO acT as a cLeaN And sanItarY surface engaged by THe back of the heaD of a PASseNgeR SittInG in the seat. The hEad ShEETs are somEtImes made
 ring vortices, which aris e from the  roll ing  up  o f th e ed ge areas of th e  fue l-containing burner st ream,  i n corp o ra te du ring th e ir f orm at io n h ot ,  a lread y b urned a nd no long erre actable flue ga ses that c aus e a quick he ati ng upof  th e  fuel /ai r mix ture a l readycontained  i n  the r i ng vort e x ,andas a result cause ap eriodic pulse- type r ea c ti o n  of  th e fuel ins id e the ring vo r te x s tru c tures that ex cites press u repulsat io ns. In ord er to  n o w p revent this  rin g vortexformat i on, the flame,as des cri bed  abo v e,  i s s ur r oun d ed  by a g as shrou dst reamthat e x i ts a t a s sm all a  radial dista nce  asp oss iblefromthefl ame o r from  thebu rner main strea m an d that ha s a  h igh er  flow speedinthe  flamepropaga t ion  d i r e ct ion than the outer  o r ed ge areas  of th e  f la m e. Thus,  a n a xial m oment um e x ch ange occ urs be t we en  the sh ro ud str ea m a ndthe f l ameor the  fuel ga s/air stream which c a uses an accel e ra t i on of t hefree flameboun d arylaye r  o r s t reambound ar y  l a yer of the fuel/air  m ixture , suc h that the pe riodic for m a t ion of r eact a bl e  vortices in t his a rea is eff e ctivelyoppos ed.
To t he extent t hat corr esp ond ing  ri n g  v ortices theno c curag ain atthe  bounda rylay erbet we en the ga s shroud  s tr ea mand  thes urroundi ng  me di um(in t h e incl udedcase ,ge n era lly flu e  g a s es),  i tis m ost  f avora blei f t he gasshroud st rea m  doe sno t conta in any fuel,si nce then n ofue l-cont a i ning vor tex could then form fro m  the (f uel -free ) sh roud stre am,  which  co u ld lea d to a  peri od icp u lse-t y p erea ct ion of the f uel  andth us t o an ex citation of flame/ p res sure pulsatio nsas t h e yocc u rf oran on- s h rouded flame or  fuel/airst r ea m.
In a mo r e p re ferredmanner,  with the non -fuel con taining g as  oft h e s hroud stre am, this  involves air,w hi ch is  av ailabl eeve rywhe re ins uff icien t quan ti ty. It  is,ho wever, a lso conceivable to usean ine rt ga s h ere which , o f  co urse, wou ld h ave a cert ain  co st di sad v antag e as ares u lt. T he p r esent inv e nt ion r el ates to a p i l l ow- headr est arrang emen t for use with as eat and partic ular l y  fo r u s e by  a  passenger sea ted  i n a mass t ra nsportation  vehicle ,s uch a s a ra ilroad  car, a b us ,  an ai rpla neor even a  pa ss e nger ca r. 
I t  is co mmon  p ractic e to d r apeo v er the back of t he se a t  of r a ilr oad c oa ch cars ,  int ercity bus es, and mor e part icul arlyairplan es , a sa nit ar y head clo t h or shee t rem ovablyat tach edto the  top o f eac h se at  ba ck and dr a p ed ov er the  fro nt of  t he s eat backt o act as  ac lean an dsan i t ary su r fa c e  engaged b y t he ba c k  of the he a d of ap assen ger si ttingin thes eat .The hea d s h e ets are s ometimesm ade 
 ring_vortices, which_arise from the rolling_up of_the_edge areas_of_the fuel-containing burner_stream, incorporate during_their formation hot, already_burned and no_longer_reactable flue gases that cause a quick heating up of the fuel/air mixture already_contained_in the_ring_vortex,_and as a result cause_a periodic pulse-type reaction of_the fuel_inside the ring vortex structures that excites pressure_pulsations.
In_order to now_prevent this ring vortex formation, the flame, as described_above, is surrounded by a gas_shroud stream that_exits_at_as small a radial_distance as possible from the flame_or from the burner main stream_and that has a higher flow speed_in the flame propagation direction than_the outer or edge areas_of the_flame. Thus, an axial momentum_exchange occurs between_the shroud_stream and the_flame or the fuel gas/air stream_which causes an_acceleration of the free flame boundary_layer_or stream boundary_layer_of_the fuel/air_mixture, such that_the_periodic formation_of_reactable vortices in this area is_effectively_opposed.
To the extent that corresponding ring vortices_then occur again at_the_boundary layer between the_gas shroud stream and the_surrounding medium (in the included case,_generally flue_gases), it_is most favorable if the gas shroud stream does not contain_any fuel, since then no fuel-containing_vortex could then form_from the_(fuel-free)_shroud stream, which_could_lead to_a periodic pulse-type reaction of the fuel_and thus_to an excitation of flame/pressure pulsations_as they occur for_a_non-shrouded flame or fuel/air stream.
In a_more preferred manner, with the non-fuel_containing gas of the shroud_stream,_this_involves air, which is available_everywhere in sufficient quantity. It is,_however, also conceivable_to use an inert gas here which,_of_course, would have a certain cost_disadvantage_as a result. The present invention_relates_to_a pillow-headrest arrangement for use_with a seat and particularly for_use by a passenger seated in a mass transportation_vehicle, such as_a railroad car, a bus,_an_airplane_or even a passenger car.
It is common practice to drape_over the_back of the_seat of railroad coach cars, intercity buses, and more particularly_airplanes, a sanitary head cloth or sheet_removably attached to the top of each seat back and draped_over the front of the seat back to_act as a clean and sanitary surface_engaged by the back_of_the head of a passenger sitting in_the_seat._The_head sheets are_sometimes made