Yakhnо O., Seminskaya N.
The National Technical University of Ukraine «Kyiv Polytechnic Institute», Kyiv, Ukraine (
Abstract. The subject of study presented in this paper is a flow of a viscous fluid in forming tool for multilayer jet production.
The purpose of this work is to carry out experimental and theoretical studies of initial part of a two-layer jet stream of viscous Newtonian fluids. The methodology and main results of work. On the basis of the results of experimental studies which carried out by authors was found that flows of two-layer jet stream of viscous Newtonian fluids in nozzles are unstabilized and consisted of a number of zones such as: a) zone of separated flow with area of unstabilized flow with changing hydraulic section l1 ; b) zone of unstabilized flow with constant hydraulic section l2 ; c) zone of stabilized flow with constant ratio of layers l3 . The equation of motion which takes possibility to analyze a fluid flow in zone l2 is given. For satisfactory results leads calculation of flow parameters by the method described by H. Schlichting on the basis of which the value of ux was determined, and proved that in
process of liquid flow speed of contact in layers is changed from вх uk to cт uk . Using graphic-analytical method described in 
length of zone l2 was evaluated based on the analysis of flow kinematic characteristics in layers 1 and 2 .
Conclusions. Obtained results of experimental and theoretical studies proves that:
- The basic formation of the velocity field and the flow stress is on the geometric initial section;
- For water the value of lн.у. with other equal conditions (,,) is 1,2
lн.у. 0,0147Re 0 which is close to the results obtained
by L. Schiller, S. Targ and others;
- Average increase of the initial segment length in two-layer flow is about of 18.5%, that is 1,2
lн.у. 0,0033Re 0 ;
- The interaction of jet flow connected with features of the flow in area of contact of liquid layers and it leads to increase of a value
of parameter lн ; - The nature of the fluid flow at the interface between the layers in area of its two-dimensional flow can have a significant impact on
the structure of the surface of the liquid surface outside the nozzle when ratio of thickness 1
2 8...10 ; - On the basis of experimental data can be recommended for Newtonian fluids formula 1,2
lн.у. (l1 l2 ) 0,018(Re1 Re2 ) 0 .
Keywords: multi-layered, unsteady-state, nasadok, initial area
1. Semynskaja N.V., Jahno B.O. Vlyjanye geometrycheskyh y prochnostnыh parametrov strueformyrujushhyh ustrojstv na kompaktnost' struy [Influence of geometric and strength parameters strueformiruyuschih devices on a jet], Visnyk Shidnoukrai'ns'kogo nacional'nogo universytetu imeni V. Dalja, 2007, no 109, Ch.2, p.p.143-148.
2. Jahno O.M., Savchenko N.V. Gidravlichni pryncypy strumynevyh metodiv rizannja materialiv [Hydraulic principles strumynevyh methods of cutting materials]. Procesy mehanichnoi' obrobky v mashynobuduvanni. Zh.: ZhDTU, 2005,Vyp. 1. p.p. 250 - 259
3. Anufriev V.A., Jahno O.M., Petuhov A.D.. O haraktere dvuhslojnnogo techenija rasplavov polimerov [The nature of the twolayer flow of polymer melts], [Materialy Vsesojuznogo simpoziuma po reologii. Sbornik Reologija polimernyh i dispersnyh sistem, reofizika. no.1, Minsk, 1975, р.p. 218-228
4. Fridman M.L., Malkin A.N., Vlasov V.I.. Dvuhslojnye techenija rasplavov polimerov v kol'cevyh golovka jekstruderov. [Two-layer flow of polymer melts in circular die]. Plasticheskie massy 1975, no 3. p.p. 29-32.
5. Jahno O.M., Voroncov E.G.. Pole skorostej na laminarnom vhodnom uchastke techenija pljonki vjazkih zhidkostej pri ih raspredelenii po orashaemomu perimetru [Velocity field at the entrance of a laminar film flow of viscous fluids at their distribution on the perimeter orashaemomu], Himicheskoe mashinostroenie. Kiev, Tehnika, no 21, 1976, p.p.90-104.
6. Voroncov E.G., Jahno O.M. Dlina nachal'nogo uchastka oroshaemyh pljonok [The length of the initial part of the irrigated films] Sbornik Gidromehanika AN USSR, no38, 1978., p.p. 97-104.