Segmented Impeller Blades for Fuel Boost Pump Reliability
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Solution Overview
Problem
Conventional aircraft jet engine mounted fuel boost pumps face challenges in maintaining pressure and flow efficiency under varying altitude conditions and abnormal operations, with limitations in pressure rise and susceptibility to contaminants, while also needing to handle extreme temperature and flow rate variations.
Innovation Solution
The design incorporates an impeller with a radial blade section and an axial inducer section, optimized using analytical and empirical models, computational fluid dynamics, and manufacturing techniques to ensure efficient pressure rise and flow management, with specific blade geometries defined by Cartesian coordinates to manage suction conditions and prevent contaminant passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine mounted boost pump is designed to maintain pressure under all operating conditions, then reliability is improved, but device complexity increases due to multiple operating mode requirements
Solution Approach 1:
The impeller is segmented into two distinct blade sections: an axial inducer blade section for abnormal operation conditions and a radial impeller blade section for normal operation conditions. This segmentation allows each section to be optimized for its specific operating mode, enabling the pump to maintain reliability across all conditions without requiring an overly complex overall design.
Solution Approach 2:
The pump design incorporates dynamic adaptability through the dual blade configuration that can handle varying operating conditions. The axial inducer blades are specifically designed to handle vapor-laden flows during abnormal operations, while radial blades handle normal liquid flow, allowing the system to dynamically adapt to different flight phases and tank pressure conditions.
2Strength
If the maximum pressure rise is limited to protect the fuel oil heat exchanger, then component safety is improved, but the pump's ability to meet demand during high-flow conditions deteriorates
Solution Approach 1:
The blade geometry parameters are specifically optimized to control the pressure-rise characteristics. The axial inducer blades have different geometric parameters compared to radial blades, allowing the system to achieve appropriate pressure rise levels that protect the heat exchanger while maintaining sufficient flow delivery capability during takeoff and climb phases.
3Reliability
If minimum impeller blade spacing is increased to allow contaminant passage, then reliability is improved, but pump efficiency deteriorates due to larger clearances
Solution Approach 1:
The blade design incorporates local quality variations with different blade sections having different characteristics. The axial inducer blades and radial impeller blades have different geometries optimized for their specific functions, allowing the system to maintain appropriate blade spacing for contaminant passage while minimizing the negative impact on overall pump efficiency through localized optimization.
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
The solution ensures uninterrupted fuel flow and pressure delivery to the engine, maintaining efficiency across normal and abnormal operations, and effectively handles extreme temperature and flow rate variations, while preventing contaminant entry.
Implementation Method 1
The impeller includes an inducer section comprising a hub including a plurality of axial blades extended therefrom... and an impeller section having a plurality of radial blades extended from the hub
Implementation Method 2
the axial inducer blade section upstream of the radial impeller blade section, wherein the axial inducer blade section is configured to handle vapor pockets and prevent cavitation
Data Source
AI summary
A boost pump includes a boost cover and a main pump housing engaged opposite to the boost cover with an impeller rotatably engaged between the boost cover and main pump housing. The impeller includes an inducer section comprising a hub including a plurality of axial blades extended therefrom, each of the plurality of blades including a root, a tip, first and second surfaces, wherein the each of the first and second surfaces is defined in TABLE 1. The impeller includes an impeller section comprising a shroud extending from the hub including a plurality of radial blades extended therefrom. Each of the plurality of blades can include including a root, a tip, and opposed pressure and suction sides extending from the root to the tip, wherein the each of the pressure and suction sides is a surface defined in at least one of TABLES 2-4.