Week 4.1: Project - Steady state simulation of flow over a throttle body

PROJECT STEADY-STATE SIMULATION OF FLOW OVER A THROTTLE BODY

AIM: To run the simulation of a steady-state simulation of flow over a throttle body.

OBJECTIVE:

• Post-process the results and show pressure and velocity contours.
• Show the mesh (i.e surface with edges)
• Show the plots for pressure, velocity, mass flow rate, and total cell count.
• Create an animation in which its throttle movement should be visible.
• Download the geometry attached here.

THEORY:

A throttle body is essentially a large air valve that sits between the intake manifold and the air intake pipe. An engine has one throttle body, which bolts to the intake manifold's plenum (the large air cavity in the center). A throttle body controls airflow into the engine, a crucial factor for controlling the engine's air/fuel ratio. Throttle bodies come in several shapes, sizes, and configurations and can perform several tasks outside of their normal air-metering duties.

Throttle bodies usually use butterfly valves. These valves consist of a casing with a large hole in the center, which is filled with a steel plate called a butterfly, or throttle plate. The throttle shaft is a rod that passes through the housing and is connected to the throttle cable on the outside and the throttle plate on the inside. When the throttle shaft turns, it rotates the throttle plate, allowing air to go around it and into the engine.

Steady-state Simulation:

A steady-state simulation is used to investigate the steady-state behavior of a system, where the simulation continues until the system reaches a steady state.

Like a steady-state model, dynamic models are based on first principles that cannot be violated. Conservation laws, phase equilibria, heat and mass transfer, and kinetics are also applied in dynamic models. The most significant difference between steady-state and dynamic simulation is that steady-state assumes that variables are constant with respect to time. This means that in a steady state there is no accumulation in the system, so the overall mass and energy input matches its output. Conversely, dynamic models consider the mass and energy rate of accumulation within the system, which allows one to determine how long it would take to reach a stable condition starting from a specified initial state.

SETUP AND SOLUTION:

Geometry:

Mesh:

Setup:

Application Type	Time-based
MATERIALS:
1. Gas simulation	Standard
2. Global Transport Parameters	Standard
3. Reaction Mechanism	Standard
SOLUTION PARAMETERS
1. Run Parameters Steady-state monitor:	Steady-state solver>Full hydrodynamic>Compressible Mass flow rate
2. Simulation time parameters
3. Solver parameters	Navis-stokes solver scheme: PICO Navis-stokes solver type: pressure-based Max convection CFL limit: 0.5
BOUNDARY CONDITIONS
1. Inlet
2. Outlet
3. Elbow-wall
4. Throttle
INITIAL CONDITIONS AND EVENTS
1. Regions and initialization
PHYSICAL MODELS	RNG- k-epsilon
GRID CONTROL
1. Base mesh	dx = 2e-3m, dy = 2e-3m and dz = 2e-3m
2. Fixed embedding
OUTPUT/POST-PROCESSING
1. Post variable selection	Standard
2. Output files:

Then Export the Files

Then continuing the setup in Cygwin :

• leading to the folder where the exported files are saved
• Then using mpiexec.exe -n 2 converge.exe restricted to simulate the setup
• After the output is generated, we lead the Cygwin to the output folder, and by copying the post_convert folder and
• Using mpiexec.exe -n 2 post_convert.exe and converting these files for processable output in ParaView.

Solution:

Mass flow rate plot:

Velocity Counter:

Velocity Vector counter:

Total Cell Count:

Animation:

Velocity:https://youtu.be/vDKws_rko7U

CONCLUSION:

• Due to the fixed embedding of the throttle valve, the simulations near it become clear as the number of cell count got increased in the specified region.
• The velocity increases near the elbow valve since the area is less and pressure get dropped in the region which causes the velocity to increase.
• The velocity of the fluid decreases when it collides with the throttle valve.
• It also causes the formation of the stagnation point due to an increase in pressure and a decrease in velocity.