Accurate prediction of temperature distribution in engine cylinder blocks and cylinder heads is critical for optimizing thermal management and preventing structural failures. This study presents a bidirectional fluid-structure interaction (FSI) approach combined with heat flux correction to analyze temperature fields in a small-displacement gasoline engine. Validation through experimental measurements demonstrates the effectiveness of this methodology in engine cylinder block development.
1. Fundamental Theory
The energy conservation principle governs the heat transfer at fluid-solid interfaces:
$$ K_{\text{cond}} \frac{\partial T}{\partial n} \bigg|_{w} = h_{\text{conv}} (T_f – T_w) $$
where $K_{\text{cond}}$ represents thermal conductivity, $h_{\text{conv}}$ denotes convective heat transfer coefficient, and $T_f/T_w$ indicate fluid/wall temperatures.
The $k$-$\epsilon$ turbulence model calculates fluid-side heat transfer characteristics:
$$ \frac{\partial}{\partial t}(\rho k) + \frac{\partial}{\partial x_i}(\rho k u_i) = \frac{\partial}{\partial x_j}\left[\left(\mu + \frac{\mu_t}{\sigma_k}\right)\frac{\partial k}{\partial x_j}\right] + G_k + G_b – \rho\epsilon $$
$$ \frac{\partial}{\partial t}(\rho\epsilon) + \frac{\partial}{\partial x_i}(\rho\epsilon u_i) = \frac{\partial}{\partial x_j}\left[\left(\mu + \frac{\mu_t}{\sigma_\epsilon}\right)\frac{\partial \epsilon}{\partial x_j}\right] + C_{1\epsilon}\frac{\epsilon}{k}(G_k + C_{3\epsilon}G_b) – C_{2\epsilon}\rho\frac{\epsilon^2}{k} $$
2. Fluid-Solid Coupling Analysis
The engine cylinder block’s cooling system demonstrates complex heat flux patterns:
| Component | 3D Heat Flux (kW) | 1D Heat Flux (kW) | Correction Factor |
|---|---|---|---|
| Combustion Chamber | 1.32 | 2.2 | 1.67 |
| Exhaust Port | 16.0 | 18.2 | 1.14 |
| Cylinder Liner | 2.54 | 2.2 | 0.87 |
3. Temperature Field Characteristics
The engine cylinder block exhibits distinct thermal gradients:
$$ Q = -kS\frac{dT}{dx} $$
where $Q$ represents heat flux, $S$ denotes cross-sectional area, and $\frac{dT}{dx}$ is temperature gradient.
Key findings for engine cylinder block temperature distribution:
| Measurement Point | Simulation (°C) | Experiment (°C) | Error (%) |
|---|---|---|---|
| Inter-cylinder Top | 177.0 | 169.0 | 4.7 |
| Liner Mid-depth | 165.7 | 161.5 | 2.6 |
| Coolant Channel | 132.0 | 133.1 | 0.8 |
4. Experimental Validation
Thermocouple measurements confirm the engine cylinder block’s thermal behavior:
$$ \text{Error Rate} = \frac{|T_{\text{sim}} – T_{\text{exp}}|}{T_{\text{exp}}} \times 100\% $$
Cylinder head validation results:
| Location | Simulated Temp. (°C) | Measured Temp. (°C) | Deviation |
|---|---|---|---|
| Exhaust Bridge | 214 | 224 | 4.5% |
| Intake Valve Seat | 180 | 185 | 2.7% |
5. Conclusion
The proposed methodology achieves ≤4.9% error in engine cylinder block temperature prediction, demonstrating significant advantages for thermal management system design. The heat flux correction approach effectively bridges 1D system analysis and 3D detailed simulation, providing reliable temperature field data for engine cylinder block optimization.
Future work will focus on transient thermal analysis and multi-phase cooling effects in engine cylinder blocks, particularly during cold start and high-load conditions. This research establishes a robust framework for thermal analysis in internal combustion engine development.