Multiple Channel Diffuser for Turbopump Pressure Recovery
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Solution Overview
Problem
Turbopumps experience significant pressure losses in diffusers, primarily due to mixing losses, leading edge incidence losses, trailing edge expansion losses, and skin friction losses, which limit efficiency and cause radial side loads on bearings, reducing reliability and increasing engine size and weight.
Innovation Solution
The Multiple Channel Diffuser design features an annular radial inlet with separate passages for gradual expansion and merging of flow, eliminating mixing losses by minimizing pressure and velocity gradients, and allowing for flexible configuration in passage shapes and orientations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional diffuser (vaneless, airfoil, or vane island) is used, then the pump or compressor can operate, but mixing losses account for more than 20% of total pressure loss from impeller discharge to volute
Solution Approach 1:
The diffuser is divided into multiple separate passages (typically 3-5 passages) that extend radially outward from the impeller discharge. Each passage acts as an independent flow channel, preventing mixing between adjacent flows. This segmentation eliminates mixing losses while maintaining gradual expansion, directly resolving the contradiction between energy loss and pressure recovery.
2Reliability
If the volute tongue is present, then the volute can be formed, but it causes a circumferential static pressure gradient that propagates through the diffuser to the impeller, creating radial side load on bearings
Solution Approach 1:
The volute tongue is completely removed from the design. The multiple passages discharge directly into the volute chamber without any tongue obstruction. This extraction eliminates the source of circumferential pressure gradients, preventing radial side loads on bearings and improving reliability.
3Loss of energy
If the diffuser passages are designed with gradual expansion, then pressure recovery is improved, but the diffuser size increases
Solution Approach 1:
The diffuser passages expand in the radial dimension rather than requiring extensive axial or circumferential space. By utilizing the radial direction for gradual expansion, the design achieves efficient pressure recovery without significantly increasing the overall diffuser volume, resolving the contradiction between pressure recovery and size.
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 results in a 20% or greater increase in pressure recovery, enabling smaller, lighter turbopump stages with enhanced mission capability, reduced engine size, and increased bearing life by minimizing radial side loads.
Implementation Method 1
A pump or a compressor such as a Turbopump uses a diffuser to convert the dynamic pressure exiting the pump or compressor into static pressure rise at the volute exit
Implementation Method 2
The impeller discharge pressure is expanded gradually and efficiently in discrete passages
Data Source
AI summary
A multiple channel diffuser having an annular shaped radial inlet and a tangential outlet, and a plurality of separated diffuser channels connecting the radial inlet to the tangential outlet such that a flow does not mix. A tap-off passage can be used to provide flow to a gas generator or a preburner. A cross-over passage can also be used to provide flow from a first diffuser to a second diffuser.