Optimizing Fluid Flow for Diesel Heads with Pressurized Intake Systems

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Discussion Overview

The discussion revolves around optimizing fluid flow in diesel engine heads, particularly in the context of pressurized intake systems such as turbocharged and supercharged engines. Participants explore the differences in fluid dynamics between naturally aspirated (N/A) and forced induction scenarios, as well as the implications for engine performance and design.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant notes the importance of understanding fluid flow in both N/A and forced induction situations, emphasizing the need to consider the valve job changes in turbocharged or supercharged engines.
  • Another participant suggests that the principles of fluid dynamics, such as those illustrated by the Venturi effect and De Laval nozzle, remain applicable, with the primary difference being the density of the charge in forced induction systems.
  • A different viewpoint highlights that supercharged engines operate at higher temperatures, which necessitates adjustments to seat width, and points out that diesel engines are more fuel-based in performance rather than air-based.
  • One participant raises a question about the concept of body force in gas dynamics, specifically whether a turbocharger can be considered a source of body force similar to gravity.

Areas of Agreement / Disagreement

Participants express various viewpoints on the principles of fluid flow in diesel engines, with some agreement on the importance of adapting techniques from N/A applications to forced induction. However, there is no consensus on specific adjustments or the implications of these principles in practice.

Contextual Notes

Participants mention various factors affecting fluid flow, such as cross-sectional area, valve design, and the impact of temperature and pressure on gas behavior, but these aspects remain unresolved and are dependent on specific conditions and definitions.

Who May Find This Useful

Individuals interested in automotive engineering, particularly those focusing on diesel engine performance, fluid dynamics, and forced induction systems may find this discussion relevant.

Fahlin Racing
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So recently I have started a project of porting diesel heads and see how well I can improve them and of course diving into fluid flow. Now, I know we are dealing with a different beast being pressurized dry-flow system, and I was told the valve job changes when you are turbocharged or supercharged. I was just wondering if somebody could teach me some fluid flow in N/A and forced induction siutuations. I have been told as well that its 'just get the air in and out like a N/A engine' but I just want to cover all points and view it from the physics side of things.

I had read Charles Fayette Taylor's ICE in Theory and Practice, the short appendix in his Vol 1. Throughout either volume of his (1 or 2) I haven't really seen much of anything specifying specifically to forced induction as far as fluid flow, however I could have missed something though, I am not exactly sure.

Realizing our CSA, layout and shape can effect the flow as well as the valve job (including valve) the convergent and divergent sides are equally if not most important using any style of valve. In this case just your basic poppet valve.

:D
 
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A thought I had was looking at how the Venturi works and how the De Laval Nozzle does too. From what I am told, flow, the only real difference is the density of the charge but improving the general idea is the same as a N/A application.
 
Supercharged engines run hotter, so seat width needs to be adjusted. Diesels are fuel-based performance, not air-based, so consider that you can get a lot more exhaust with the same amount of air when the fuel supply jumps up. Overall though, it's just an air passage, but the exhaust has to work harder in diesels. HTH
 
After some reading of gas dynamics the mentioning of internal energy referring to the simple gases rely on energy within the system. Example given was temperature and pressure of what a gas inside a port depends on. After that they mention what is known as a 'body force', would a turbocharger produce the body force the gas relies on? would that be a good correlation since gravity can be used as body force?
 

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