Diffuser Guide Vane Asymmetry for Radial Turbomachine Pressure Loss
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Solution Overview
Problem
Current designs for radial turbomachines with impellers and diffusers lack a comprehensive technical teaching to reliably improve aerodynamics, particularly in the guide vanes of the diffuser, leading to inconsistent pressure loss reduction depending on flow conditions.
Innovation Solution
The guide vanes are designed with a specific geometry where the leading edge angle is smaller on the cover disk side than on the wheel disk side, and the angle of attack varies along the blade height, with a difference of at least 5°, and the guide vanes are inclined such that the leading edge on the cover disk side is offset by at least 10% of the axial channel width, optimizing flow entry into the diffuser.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional guide vane designs are used in the diffuser, then the structure is simple, but pressure loss is high and aerodynamic performance is inconsistent depending on flow conditions
Solution Approach 1:
The guide vanes are designed with different geometric properties at different locations: the leading edge angle varies along the blade height (smaller on cover disk side, larger on wheel disk side), and the angle of attack varies along the span. This local variation optimizes flow guidance at each specific location, reducing vortex formation and pressure loss while maintaining manageable manufacturing complexity through systematic geometric progression.
Solution Approach 2:
The guide vane geometry is intentionally made asymmetric with respect to the blade height direction. The leading edge angle and angle of attack differ between the cover disk side and wheel disk side, creating an asymmetric flow guidance pattern that better matches the non-uniform flow conditions in the diffuser, thereby reducing energy loss while the overall structure remains relatively simple.
2Loss of energy
If uniform guide vane geometry is used along blade height, then manufacturing is easier, but vortex formation increases and aerodynamic performance deteriorates
Solution Approach 1:
The guide vane geometry parameters (leading edge angle and angle of attack) are systematically varied along the blade height direction. The leading edge angle decreases from wheel disk side to cover disk side, and the angle of attack varies along the span, creating optimized flow guidance that reduces vortex formation. These parameter changes follow systematic patterns that can be manufactured with standard precision capabilities.
3Loss of energy
If guide vanes are not inclined with offset leading edges, then manufacturing is simpler, but flow entry into the diffuser is suboptimal and pressure loss increases
Solution Approach 1:
The guide vane design incorporates inclination in the circumferential direction with offset leading edges, adding a dimensional aspect to the geometry. The leading edge is offset in the circumferential direction by at least 10% of the axial channel width, creating a three-dimensional flow guidance structure that optimizes flow entry into the diffuser while reducing pressure loss. This dimensional addition is achieved through straightforward geometric offset that can be manufactured with standard capabilities.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration results in a harmonic, low-pressure-loss flow guidance by reducing vortex formation and enhancing aerodynamic properties, ensuring efficient fluid flow through the turbomachine.
Implementation Method 1
a stationary diffuser located downstream of the impeller and equipped with guide vanes... the diffuser extends substantially radially along a main flow direction... the guide vanes extending axially along a blade height direction and radially along a flow direction
Implementation Method 2
a stationary diffuser located downstream of the impeller... diffuser has a diffuser inlet for a substantially radial inflow and a diffuser outlet
Data Source
Figure 1~2
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AI summary
The invention relates to an arrangement (ARG), through which a process fluid (PFF) can flow along a main flow direction (MFD), comprising an impeller (IMP) that can rotate about an axis (X) in a rotation direction (RTD) and a stationary diffuser (DFF) located downstream of the impeller (IMP) and being provided with guide vanes (VNE), wherein the impeller (IMP) has an inlet (ILI) for a substantially axial supply flow and an outlet (EXI) for a substantially radial out-flow, wherein radially and axially extending rotor blades (BLD) are arranged between a wheel disc (HWI) and a cover disc (SWI) of the impeller (IMP), the impeller channels (ICH) are separated from one another in a circumferential direction (CDR), wherein the diffuser (DFF) extends substantially radially along a main flow direction (MFD), wherein the diffuser (DFF) has an axial cover disc side (SWS) and an axial wheel disc side (HWS), which delimit an axial channel width (SAC) of the diffuser (DFF) between them, wherein the diffuser (DFF) has a diffuser inlet (ILD) for a substantially radial supply flow and a diffuser outlet (EXD), wherein guide vanes (VNE) extending axially along a blade vertical direction and radially along a through-flow direction are arranged between the wheel disc side (HWS) and the cover disc side (SWS) of the diffuser (DFF), which separate the guide vane channels (HCN) from one another in a circumferential direction (CDR). According to the invention, an inlet edge angle (LEA) for every axial blade height is defined as an angle between an inlet edge tangent (TLV) on a mean line (BWL) on an inlet edge (DLE) of the respective guide vane (VNE) and a circumferential tangent (CTG) through the inlet edge, wherein the inlet edge angle (LEA) is smaller on the cover disc side than on the wheel disc side.