Fluid Curtain Honeycomb Flow Shaping to Reduce Air Entrainment
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Solution Overview
Problem
Existing fluid curtain technologies, such as air curtains, suffer from high ambient air entrainment due to turbulent transition layers, leading to increased thermal and particle loads, which in turn elevate refrigeration and cleaning costs in environments like refrigerated display cases.
Innovation Solution
A honeycomb structure with parallel conduits is used to laminarize the flow and suppress instabilities, combined with a mechanical deflector that alters the velocity profile to a smooth skewed parabolic shape, reducing entrainment by maintaining a laminar transition layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional air curtains are used to separate environments with different temperatures, then thermal separation is achieved, but ambient air entrainment increases due to turbulent transition layers
Solution Approach 1:
The invention changes the flow regime parameter from turbulent to laminar by using a honeycomb structure with specific conduit dimensions that maintain Reynolds number below the transition threshold. This parameter change eliminates turbulent mixing at the interface while preserving thermal separation, thereby reducing ambient air entrainment and associated energy losses.
Solution Approach 2:
The honeycomb structure acts as an intermediary device between the air curtain flow and the ambient environment. Its parallel conduits with controlled cross-sectional areas serve as flow conditioning elements that mediate the transition from turbulent to laminar flow, reducing direct turbulent interaction and entrainment at the interface.
2Reliability
If multiple air curtains are used to reduce entrainment, then separation effectiveness improves, but device complexity increases
Solution Approach 1:
The invention segments the air curtain flow into multiple parallel streams through the honeycomb structure's conduits. Each conduit produces a controlled laminar sub-flow that collectively forms the air curtain. This segmentation achieves reliable separation effectiveness through laminar flow control while using a single integrated device rather than multiple separate air curtains.
Solution Approach 2:
The honeycomb structure performs multiple functions simultaneously: it segments the flow, conditions the velocity profile, suppresses instabilities, and maintains laminar flow regime. This multi-functionality achieves reliable separation with a single device, eliminating the need for multiple separate air curtain systems.
3Stability of the object's composition
If turbulent flow is used in the air curtain, then flow mixing occurs, but ambient air entrainment increases
Solution Approach 1:
The invention changes the flow regime parameter from turbulent to laminar by designing the honeycomb conduits with specific dimensions that maintain Reynolds number below the transition threshold. This parameter change eliminates turbulent mixing while preserving controlled flow stability, thereby reducing ambient air entrainment and energy losses.
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 significantly minimizes ambient fluid entrainment into the fluid curtain, thereby reducing thermal and particle loads and lowering refrigeration or cleaning costs.
Implementation Method 1
The conduits are configured to laminarize the flow for the fluid curtain, and to guide the flow and suppressing instabilities in the flow downstream of it
Implementation Method 2
the Reynolds number of flow when flowing out from the honeycomb structure is advantageously below 6000, more advantageously below 5000 and most advantageously around 1000
Implementation Method 3
The conduits are configured to laminarize the flow for the fluid curtain, and to guide the flow and suppressing instabilities in the flow downstream of it. The suppressing of instabilities is performed at least in perpendicular direction to walls of said conduits
Implementation Method 4
the velocity profile of the flow after the honeycomb structure is a (advantageously smooth) skewed parabolic velocity profile with a peak shifted from the centre line of the symmetrical parabolic velocity profile
Implementation Method 5
the relative velocity and change of relative velocity in the transition layer with the second environment fluid (such as warm ambient air) is small, which keeps the transition layer with the second environment fluid as laminar as possible thereby minimizing entrainment of the ambient fluid into the fluid curtain
Data Source
AI summary
A module (100) with a flow channel (102) for providing a fluid curtain (101), such as an air curtain, between different environments, comprises an inlet (103) for introducing a fluid flow through said flow channel (102) of the module and an outlet (104) for introducing said fluid curtain. In addition the module comprises a honeycomb structure (105) with plurality of parallel conduits (106) before the outlet (104) in order to laminarize the flow for the fluid curtain, and guiding the flow and suppressing instabilities in the flow downstream of it. Furthermore the module comprises a mechanical structure (105, 107) before the outlet (104). The mechanical structure is configured to change the velocity profile of the flow before (107) the honeycomb structure or during (105) the honeycomb structure so that the velocity profile of the flow after the honeycomb structure (105) or outlet (104) is a smooth skewed parabolic velocity profile with a peak (108) shifted from the centre line (109) of the symmetrical parabolic velocity profile.