1. A method for evaluating the constriction in a fluid-filled tube with a pressure wave of a fluid stream containing a component due to a back pressure flow and a component caused by a direct pressure flow, without performing measurements of the flow rate, comprising: taking pressure measurements in the tube； separating the pressure components into the component due to the back flow pressure and component due to the direct flow of pressure； identification of the time window when the flow velocity differential (dU) is I have minimal or absent； and obtaining the back pressure and pressure components for pressure measurements taken at least in the time window. 2. The method according to claim 1, additionally providing for the components of the back pressure and pressure during the time window. The method according to claim 1 or 2, in which the time window is characterized by the length from the time moment tw to the time moment tw, and the component (P) due to the direct pressure stream is equal to: and the component (P) due to the back pressure stream is equal to: 4. The method according to claim 3, in which the ratio of the isolated pressures provides an estimate of the degree of reduction in the cross section of the tube, the ratio of the isolated pressure head is: P / P and the ratio of the isolated back pressure is: P / P.5. The method according to claim 1 or 2, wherein the time window is identified by analyzing the characteristics of the pressure waveform. The method according to claim 1 or 2, in which the time window is identified as starting at a given point in time after an identifiable event and continuing for:1. Способ оценки сужения в заполненной жидкостью трубке с волной давления потока жидкости, содержащей составляющую обусловленного обратным потоком давления и составляющую обусловленного прямым потоком давления, без осуществления измерений скорости потока, предусматривающий:выполнение измерений давления в трубке；разделение составляющих давления на состав
