|2.723 Change of state quantities inside diffuser|
i [J·kg-1] specific enthalpy of gas; s [J·kg-1·K-1] specific entropy; t [°C] temperature of gas; p [Pa] pressure of gas. Subscript c denotes stagnation state of gas.
|3.727 Change of state quantities of gas inside the supersonic diffuser|
i* [J·kg-1] critical enthalpy; a [m·s-1] speed of sound.
|6.405 Efficiency of diffuser|
η [-] Efficiency of diffuser – referred to static state of gas*.
|8.411 Hydraulic efficiency of diffuser|
|9.458 Cone diffuser|
r [m] radius; α [°] angle of diverging; l [m] length of diffuser; x [m] axis scale.
|10.631 Influence angle of diverging of cone diffuser on pressure drop|
Graph in scale is shown in [1, p. 382].
|11.418 Principle of flow separation of boundary layer from diffuser wall and developed of recirculation|
R.P. velocity profile.
|12.427 Practical solutions of space limited diffusers|
|13.428 Development of velocity profile inside throat of diffuser|
LP laminar flow; PP transition region of flow; TP turbulent flow. xe minimum length of diffuser throat for development turbulent flow of boundary layer.
|Figure at Problem 1.|
(a) calculated profile of radius; (b) cone diffuser about the same length at α=23,18°.
|Figure at Problem 2.|
Profil of pressure gradient in a cone diffuser. dp/dx [kPa·m-1]; x [mm]. The higher pressure gradient at the beginning of the diffuser is higher than in the case of Problem 1 because there is also a larger angle of expansion.
|15.430 Diffuser with linear pressure gradient|
dp/dx [kPa·m-1]; x [mm]. Diffuser on the Figure has parameters: dp/dx=400 kPa·m-1, Ri=10 mm, pi=110 kPa.
|16.831 Practical design of diffusers with variable diverging|
|18.554 Influence of input velocity change on subsonic diffuser function|
There are three cases with cia<cib<cic=a. In individual cases, the back pressure also changes, if it were still the same (pe=pea), the diffuser would behave like a short diffuser. At less than the critical pressure p*, a shock wave arises behind the narrowest cross-section and, in addition, when the back pressure decreases below pec the Laval nozzle becomes a diffuser see chapter 40. Flow inside de Laval nozzle at non-nominal states. L.T. Laval nozzle function area.
|19.654 Influence of input velocity change on supersonic diffuser function|
There are three cases with cic<cia<cib>a. In individual cases, the back pressure also changes, if it were still the same (pe=pea), the diffuser would behave like a short diffuser. It is changed so that the subsonic parts of the diffuser do not produce a shock wave(5). In the variant c, the convergent part of the diffuser is not able to accommodate such an amount of gas (it will have a high resistance), therefore, before the diffuser a perpendicular shock wave is generated which increases the pressure above the critical and reduces the velocity to subsonic. Thus, the convergent part of the diffuser will function as a nozzle. The divergent portion of the diffuser will function as a Laval nozzle in a non-design state.
|20.110 Valve with diffuser (partially open)|
There is subsonic flow inside the valve. Flow control is done by changing the flow cross-section using the valve plug RK, which is either retracted (flow cross-section decreases) or extended (flow cross-section increases). At the narrowest point between the plug and the seat, the flow reaches the maximum speed, which again decreases in the diffuser.
|22.745 Geometric similarity of diffuser blade row with symmetrical diffuser|
|23.864 Development of λ-shock wave in blade row of compressor|
RV shock wave and separtion of flow.
This document is English version of the original in Czech language: ŠKORPÍK, Jiří. Proudění plynů a par difuzory, Transformační technologie, 2016-03, [last updated 2018-11-26]. Brno: Jiří Škorpík, [on-line] pokračující zdroj, ISSN 1804-8293. Dostupné z https://www.transformacni-technologie.cz/41.html. English version: Flow of gases and steam through diffusers. Web: https://www.transformacni-technologie.cz/en_41.html.