Project Transient simulation of flow over a throttle body

AIM: Steady state simulation of flow over a throttle body using converge studio.

OBJECTIVE

• To perform Transient simulation of fluid flow over a throttle body.
• To post-process results and show pressure and velocity contours for both the cases.
• To show the plots for pressure, velocity, mass flow rate and total cell count.

Throttle body

The throttle body is the part of the air intake system that controls the amount of air flowing into the engine, in response to driver accelerator pedal input in the main. The throttle body is usually located between the air filter, box and intake manifold, and it is usually attached to, or near, the mass airflow sensor.

Transient State Simulation of Flow over a Throttle Body tells us the how the fluid interacts with the solid as in the form that the solid restricts the flow of the fluid which provides us the chance to understand , analyze and design the throttle body .

This report aims to investigate the Flow of Air inside the elbow pipe with a throttle and discuss variations in the Flow Parameters.

Since this is a Transient solver we have to set start time and End time .

For the Start Time we shall select 0 seconds , the End time can be derived by dividing the Characteristics Length by Average Velocity can multiply by the number of time we want to run the cycle for 4 times , we multiply by 4 and we get the End time .

Characteristics Length is the important length along which the fluid occurs for most time period , ie 0.11 m along y direction approximated to 0.2 , and the average velocity from the diagram assumed 80.

GEOMETRY

Dx=0.10(m)

Dy=0.11(m)

Dz=0.01(m)

MESHING

Converge CFD uses a cut-cell cartesian method. One of the most obvious benefits of the cut-cell Cartesian approach is the fact that you have a body-fitted mesh.

CASE SETUP

Case Set-up: General Flow

Materials:

Predefined Mixtures: Air

(Gas Simulation)

Simulation Parameters

Solver: Transient

Mode: Full hydro dynamics

Start time: 0 seconds

End time: 10 milli seconds

Initial time-step: 1e-9 s

Minimum time step: 1e-9 s

Maximum time step: 1.0 s

Regions and Initialization

Added Region (Air)

Pressure: 101325 Pa

Species: Air - O2 = 0.23, N2 = 0.77

Boundary Conditions

Inlet: Inflow 150000 Pa Air

Outlet: Outflow 101325 Pa Air

Throttle and Elbow wall: Wall

Velocity boundary conditions: Law of wall

Wall motion type: Rotating

Surface Movement: moving

Temperature boundary conditions: Law of wall (300K)

Base Grid:

Mesh in dx, dy and dz directions = 0.002

Fixed Embedding

Fixed embedding is used to refine the mesh around the desired regions. In this case, the regions of interest are the inner walls of the channel. Therefore, the fixed embedding is applied with a scale of 3 and 2 embedded layers.

Output files

• From Output/ Post Processing, Click on Output files -> Ok.

RESULT

Vlocity Contour

Pressure Contour

Plot 1.1:Total cell count

Ma

Plot 1.2: Mass flowrate at inlet and outlet

Plot 1.3: Pressure at inlet and outlet

Plot 1.4: Velocity at inlet and outlet

Animation

1.Velocity flow:https://youtu.be/ek9KUykG8rc

2.Pressure flow:https://youtu.be/gzT-mCY900Q

3.Throttle movement :https://youtu.be/8h_4nmTF46w

CONCLUSION:

With the results obtained we can say that the velocity and pressure varies around the Throttle Valve , with the transient flow the direction and magnitude of the flow parameter changes .

The mass flow rate follows the law of conservation of mass .

Simulation time is much more as compared to the steady State Simulation .

The base Grid can be increased but that would result in lot of time for computation .